Marine Microbial Ecology

The metabolism of one-carbon (C 1 ) compounds in the marine environment affects global warming, seawater ecology and atmospheric chemistry. Despite their global significance, marine microorganisms that consume C 1 compounds in situ remain poorly characterized. Stable-isotope probing (SIP) is an ideal tool for linking the function and phylogeny of methylotrophic organisms by the metabolism and incorporation of stable-isotope-labelled substrates into nucleic acids. By combining DNA-SIP and time-series sampling, we characterized the organisms involved in the assimilation of methanol and methylamine in coastal sea water (Plymouth, UK). Labelled nucleic acids were analysed by denaturing gradient gel electrophoresis (DGGE) and clone libraries of 16S rRNA genes. In addition, we characterized the functional gene complement of labelled nucleic acids with an improved primer set targeting methanol dehydrogenase (mxaF) and newly designed primers for methylamine dehydrogenase (mauA). Predominant DGGE phylotypes, 16S rRNA, methanol and methylamine dehydrogenase gene sequences, and cultured isolates all implicated Methylophaga spp, moderately halophilic marine methylotrophs, in the consumption of both methanol and methylamine. Additionally, an mxaF sequence obtained from DNA extracted from sea water clustered with those detected in 13 C-DNA, suggesting a predominance of Methylophaga spp among marine methylotrophs. Unexpectedly, most predominant 16S rRNA and functional gene sequences from 13 C-DNA were clustered in distinct substrate-specific clades, with 16S rRNA genes clustering with sequences from the Gammaproteobacteria. These clades have no cultured representatives and reveal an ecological adaptation of particular uncultured methylotrophs to specific C 1 compounds in the coastal marine environment.

El deterioro del agua del embalse de Bellús, ha ocasionado procesos de eutrofización, dando como resultado que la calidad de sus aguas sea pésima para su uso. En este estudio se ha desarrollado la modelación matemática de la calidad del agua del Embalse ...

The presence of Ophiothrix synoecina Schoppe in the Guajira area (Cabo de la Vela), and the contribution of new information about its distribution and density, allowed the reevaluation of the category proposed on the Marine Invertebrates Red List, because of its small and fragmentary area of nine localities through the Colombian Caribbean rocky-shore.

This paper reports the detection of Pseudothyone belli on submerged hard substrates at three sites in Santa Marta during port surveys conducted in March and October 2010. Owing to its high adaptive and competitive capability, it appears likely that the species has established itself in the Colombian Caribbean.

To characterise central neurons in the pedal ganglia of both male and female green lipped mussel, Perna canaliculus immunohistochemical techniques were used. Mollusc antibodies were used against neuropeptides and neurotansmitters known to control reproduction and spawning. Anti-ELH and anti-APGWamide showed very strong immunoreactivity in small type of neurons. Anti-5-HT and anti-DA immunoreactivity was mostly in large type of neurons. The labelled neurons are consistent with descriptions of neurosecretory cells implicated in the control of reproduction and spawning on the basis of earlier histological staining techniques used in this species. The use of selective immunological markers for peptides and amines appears to be a, promising tool for further characterisation of neurosecretory cells, and to isolate an'tl characterise neuropeptides and other biologically active materials involved in the control of reproduction in Perna canaliculus.

The Mediterranean coast receives large inputs of dust with a potential fertilization effect. We evaluated the effect of a wet dust deposition event on microbial abundance and activity, community structure and metabolic balance. Dust collected during a dust storm event was added to a series of microcosms. We added a realistic concentration (0.05 g L 21 ) based on the phosphorus concentration contained in the dust and, in addition, we included a P amended tank to distinguish the effect of dust from that of the phosphorus in the dust. We also included a higher dust concentration tank (0.5 g L 21 ). Dust increased the initial water-phosphorus concentration by 0.3 mM and the dissolved organic carbon (DOC) concentration by 14 mM, and increased bacterial abundance (1.8-fold) and bacterial production (5-fold). At the end of the experiment, primary production and community respiration were stimulated by dust and by P, but the net result of the addition of low amounts of dust was an initial switch towards heterotrophy, whereas the net result of the high-dust (DH) additions and the P addition was a shift towards autotrophy. Bacterial community structure changed little between P and low dust, but these were very different from the control and the DH communities.

Este documento registra a Schizostella bifurcata, miembro de la familia Gorgonocephalidae por primera vez en el Caribe colombiano. Este registro se basa en muestras recolectadas en la plataforma continental de la Bahía de Santa Marta, donde la especie se encontró asociada a gorgonáceos.

Sediment samples collected off the coast of San Diego were analyzed for actinomycete diversity using culture-independent techniques. Eight new operational taxonomic units (OTUs) in the Streptomycetaceae were identified as well as new diversity within previously cultured marine OTUs. Sequences belonging to the marine actinomycete genus Salinispora were also detected, despite the fact that this genus has only been reported from more tropical environments. Independent analyses of marine sediments from the Canary Basin (3814 m) and the South Pacific Gyre (5126 and 5699 m) also revealed Salinispora sequences providing further support for the occurrence of this genus in deepsea sediments. Efforts to culture Salinispora spp. from these samples have yet to be successful. This is the first report of Salinispora spp. from marine sediments > 1100 m and suggests that the distribution of this genus is broader than previously believed.

Se presentan los flujos de nutrientes y metabolismo neto en la laguna costera Lobos, una laguna semi-árida subtropical del Golfo de California, México. En verano e invierno se realizaron muestreos de parámetros físico-químicos y nutrientes en agua en la laguna, mar adyacente y dren aportador de aguas residuales agrícolas. Los flujos de nutrientes y el metabolismo neto del ecosistema fueron estimados con el modelo biogeoquímico LOICZ. El tiempo de renovación del agua fue de 5 días en verano y de 12 días en invierno. La laguna fue sumidero de nitrógeno en verano (ΔNID = -5645 mol día -1 ) y en invierno (ΔNID = -136,575 mol día -1 ), fuente de fósforo en verano (ΔFID = + 360 mol día -1 ) y sumidero en invierno (ΔFID = -15,809 mol día -1 ). En verano, el metabolismo neto del ecosistema (MNE) fue heterótrofo (-0.38 mmol m -2 d -1 ) y dominó el proceso de desnitrificación ( -0.1 mmol m -2 d -1 ); en invierno, el MNE fue autótrofo (+ 16.49 mmol m -2 d -1 ) y dominó la fijación de nitrógeno ( + 1.1 mmol m -2 d -1 ). Estos resultados sugieren la hipótesis de que las lagunas costeras semi-áridas subtropicales de la costa este del Golfo de California tienen cambios estacionales, funcionando con procesos dominantes de desnitrificación y metabolismo neto heterótrofo durante verano y con procesos dominantes de fijación de nitrógeno y metabolismo neto autótrofo en invierno.

Nitrogen fixation ratio and primary production was determinated from the associated epiphytic community, and chlorophyll concentration from Posidonia oceanica (L.) Delile leaf on summer and winter 2018. It was fertilized with iron (Fe) and phosphorous (P) on 40L acuarium with water from Cala Nova (39°33'02.6"N 2°36'01.6"E). The aim of the study was to determinate how Fe and P affect on the N-fixing community of P.oceanica. It was observed that high loads of P and Fe in the water column can reduce leaf primary production of P. oceanica just after two weeks and the addition of Fe has lower effects than P. The nitrogen fixation response was different depending on the part of the plant. It wasn’t found stationarity variations on any parameter, only between treatments. The effect of this treatments was different between the N-fixing community and plant leaf (in terms of primary production and chlorophyll content). Regarding leaf chlorophylls a and b, Fe promotes product...

All hydrocarbon (HC) reservoirs leak to some extent. When small quantities of HCs escape offshore reservoirs and migrate through overlying organic-poor marine sediments towards the surface, these HCs are often completely metabolized by microorganisms before reaching the sediment–water interface. However, these low and often unnoticed upward HC fluxes still influence the geochemistry of surrounding sediments and potentially stimulate metabolic activity by microbial populations in shallow subseafloor environments. In this study, we examined how localized HC seepage affects microbial sulfate reduction in organic-poor sediments from the SW Barents Sea, focusing on three sampling areas overlying known HC deposits and two pristine seabed reference areas. The analysis of 50 gravity cores revealed significant variability in the predicted sulfate depletion depth, ranging from 3 to 12 m below the seafloor. We observed nearly linear pore water sulfate and alkalinity profiles, alongside low rates of sulfate reduction (pmol cm3 d−1). Metagenomic and metatranscriptomic data indicated metabolic potential and activity towards sulfate reduction and anaerobic oxidation of methane (AOM). Expression of functional marker genes (aprAB, dsrAB, mcrA) revealed metabolic activities by sulfate-reducing Desulfobacterota and methanotrophic ANME-1 archaea sustained by HC traces in the sediment. Furthermore, in concomitance to AOM processes, we found that archaea amongst the classes Lokiarchaeia and Thorarchaeia were expressing genes involved in sulfur reduction (hydB, hydG). Overall, our study demonstrates that the gradient in pore water geochemistry, the rates of sulfate reduction processes, and the genetic features of microbial populations actively involved in sulfate-driven AOM processes are all affected by low and often unnoticed upward HC fluxes. This slight HC seepage resulted in sulfate depletion at shallower depths compared to what would be expected at a comparable non-affected site and produced concomitant biogeochemical signatures in the shallow subsurface that enable the inference of deeply buried reservoirs.

Multiple sediment trap (MULTITRAP) arrays were deployed at 3 hydrographically and biologically distinct stations in the eastern North Pacific Ocean and used to evaluate experimentally the hypothesis that protozoan grazers are important in the diagenesis of sinking biogenic materials in the ocean. Measurements were made of adenosine triphosphate (ATP) concentrations and the abundances of bacteria and zooflagellates associated with sinking particles collected from in situ preserved and 2 sets of unpreserved (live) traps: one containing a selective eukaryote inhibitor (thiram) and the second without thiram which served as a live-control. Particulate organic carbon and nitrogen (POC and PON), NH:, NO;, NO;, dissolved organic nitrogen (DON), diatoms, and fecal pellets were quantified in live-control and live-thiram traps. In situ microbial production was estimated by measuring RNA and DNA synthesis in live-control and live-thiram traps pre-charged with 3H-adenine. Trap-collected bacteria and zooflagellates accounted for a low percentage of the total POC (2 to 11 % ) but a high percentage of the total microbial biomass (an estimated 25 to 2 100 % of total ATP). Zooflagellates were the principal protozoans collected and accounted for 2 to 25% of the total microbial biomass. Synthesis of RNA and DNA was observed at all stations and depths, indicating microbial growth in the live traps. ATP and microscopic analyses, however, independently confirmed that death rates exceeded growth rates on the sedimenting particles. Differences between the livecontrol traps (coupled microbial assemblage) and live-thiram traps (uncoupled assemblage, grazers inhibited) indicated slower decomposition and nutrient regeneration in the uncoupled system. In general, POC was higher and in the shallowest traps, NH: was lower, and DON was higher in the livethiram traps. Zooflagellates appear to strongly influence decomposition and nutrient recycling within the microbial assemblage associated with sedirnenting particles.

AlgaeBase has been under construction since 1996, initially as a database of the seaweeds of the north-eastern Atlantic for private use as an aide-mémoire. It was extended to the Mediterranean as part of an EU project. Initially programmed in FileMaker, the database was put on line in 1998, but it quickly became apparent that the internet demand for such information outstripped the capabilities of this software. In 2004, it was completely reprogrammed in MySQL, and named AlgaeBase. Although all Irish public funding abruptly ceased in 2008, we have managed to keep the data on-line. In 2012, sponsorship from Ocean Harvest, an Irish company, was received and this will allow us to continue for the present. AlgaeBase was intended to be an information source on the taxonomy and distribution of all algae, but it quickly became apparent that taxonomy is inseparable from nomenclature and we have been greatly assisted in this by having on-line access to the cards of Paul Silva"s Index Nominum Algarum. In recent years, we have put a lot of effort into adding PDFs of publications. In this we have been somewhat thwarted by the legal aspects of copyright; technically, we cannot offer PDFs of works before 1923. Nevertheless, we have managed to make available over 5,000 PDFs, many of rare and beautiful items found only in a handful of major libraries worldwide. Another issue is that of the legal requirements of the International Code of Nomenclature for Algae, Fungi, and Plants. Most problematical of all is the provision in Art. 13 for later-startingpoint dates for the families Nostocaceae, Desmidiaceae, and Oedogoniaceae (each in the original sense of defined publications). Many authors have seen fit to ignore these provisions. This is not the only article of the Code ignored by authors: many names published are invalid for reasons that some clearly regard as insignificant, or in ignorance of the requirements. In recent years, high-impact on-line journals in particular often completely ignore the necessities of the Code. Some of the conventions of taxonomy are also disregarded by authors; for example, the requirement for considering a genus taxonomically in terms of its type species. The considerable extent of this problem is evident in the number of genera that still have no type species designated, although some authors seem to have no issues with describing a new entity without even mentioning its type. Some recent taxonomic proposals are also invalid as the entity proposed included the type of another name. The proverb "Homo proponit, sed Deus disponit" can be applied to taxonomy in that one may be free to make any taxonomic proposals one wishes (provided somebody will publish them validly), but the final arbiter of acceptance is usually some authoritative source that surpasses all others. Essentially, like all the sciences, taxonomy is a web of hypotheses, the acceptance of which is based on the quality of the arguments presented. Unfortunately, AlgaeBase has, for some groups, become such an authoritative source for nomenclatural and taxonomic matters, which it was never intended to be. Scenedesmus (Scenedesmaceae, Chlorophyta

Marine plastic debris is a growing concern that has captured the general public’s attention. While the negative impacts of plastic debris on oceanic macrobiota, including mammals and birds, are well documented, little is known about its influence on smaller marine residents, including microbes that have key roles in ocean biogeochemistry. Our work provides a new perspective on microbial communities inhabiting microplastics that includes its effect on microbial biogeochemical activities and a description of the cross-domain communities inhabiting plastic particles. This study is among the first molecular ecology, plastic debris biota surveys in the North Pacific Subtropical Gyre. It has identified fundamental differences in the functional potential and taxonomic composition of plastic-associated microbes versus planktonic microbes found in the surrounding open-ocean habitat.

Este trabajo registra por primera vez para el Caribe colombiano la familia monogenérica Chaetasteridae (Echinodermata: Asteroidea) con base en un ejemplar de la estrella de mar Chaetaster nodosus Perrier 1875 colectado frente a las islas de San Bernardo a 98 m de profundidad. Se incluye una breve descripción de la especie e información acerca de su distribución.

Se describe la variación espacial de la materia orgánica particulada (MOP), en términos de proteínas, carbohidratos y clorofilas, así como la abundancia específica del titoplancton, para bahía Concepción durante el pico reproductivo de Argopecten circuluris. La distribucibn de estas variables evidenció dos zonas de mayor concentración de partículas: una en el primer "tercio" de la bahía y la otra en la cabecera. Los valores altos de clorofila a se debieron al nanofitoplancton, el cual contribuyó en mayor proporción a la abundancia total. Las especies abundantes del microtitoplancton fueron Chaetoceros curvisetus, Ch. lorenzianus, Ch. teres, Ch. cinctus y Lithodesmiun undulatum. El cálculo de las contribuciones de materia orgánica particulada fitoplanctónica y no fitoplanctónica mostró que en superficie el mayor porcentaje de proteínas (69.5%) está dado por el fitoplancton, mientras que a 10 m correspondió al material organito particulado no fitoplanctónico o detrítico. Esto permite inferir una alta calidad de la MOP en la columna de agua, la cual constituye una fuente potencial de alimento para los diferentes estadios de la almeja catarina.

Background: Ornamental fishkeeping is a widely embraced hobby globally. In India, Kolathur, Chennai Tamil Nadu is an important ornamental fish hub involved in trading of ornamental fishes. As a lucrative industry, the ornamental fish trade faces significant challenges due to diseases caused by various pathogens, impacting market value and causing economic losses.

Methods: A surveillance study was conducted in Kolathur, Chennai, from December 2022 to August 2023. Ornamental fish samples exhibiting clinical signs of bacterial diseases were collected from the farms and retail outlets. Bacterial isolation and identification techniques, including conventional and PCR detection, were employed to isolate and identify bacterial strains from infected fish samples.

Result: Out of 196 fish samples, 51 (29.4%) were found infected with bacterial pathogens. The prevalent bacterial pathogens included Aeromonas veronii (47%), A.caviae (17%), Pseudomonas aeruginosa (15%), Streptococcus sp. (11.3%), Mycobacterium fortuitum (5.6%) and Shewanella sp. (3.7%). Different fish families exhibited varying susceptibility to bacterial diseases, with cyprinids being the most affected (56.6%). The findings stress the importance of adhering to health regulations to prevent transboundary spread and suggest the development of targeted management strategies to sustain the health of ornamental fish populations.

The present study demonstrates the antibacterial activity of marine bacteria isolated from Velankanni Beach, Chennai, India. Five distinct isolates were identified, with Micrococcus luteus (YSD1) exhibiting the most promising antibacterial properties. The crude compounds extracted from YSD1 were examined for their antibacterial activity using the agar-well diffusion method against Proteus mirabilis ATCC 25933, Bacillus subtilis ATCC, Bacillus cereus ATCC, and methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300. Gas chromatography-mass spectrometry (GC-MS) analysis revealed 2-pentanone at high intensity, with potential applications in cancer treatment. This research underscores the potential of marine ecosystems as a source of novel antibiotics and the significance of reliable approaches in pharmaceutical discovery. Further research is required to corroborate these findings against a wider range of pathogens and to explore their ameliorative potential and mechanisms of action. The results of this study contribute to the wider field of research by spotlighting the untapped potential of marine ecosystems in bringing novel antibiotics to light, thereby paving the way for future studies to combat antibiotic resistance.

The ocean's microbiological landscape forms a complex and integral part of its ecosystem, with burgeoning research shedding
light on its significant metabolic capabilities and resilience within marine environments. Notably, pigments procured from sea-based
bacteria have gained attention for their repository of naturally occurring compounds with advantageous pharmacological properties. These pigments are distinguished by their biological colouring features and are gaining recognition for their viability in diverse
sectors, encompassing cosmetics, food production, textile manufacturing, print technology, and pharmaceutical science. The present
research centres on the isolation and molecular characterization of a pigment-synthesizing bacterial isolate, named VSB3, sourced
from marine samples extracted from the Bapatla and Yarada coastal regions. The unearthing of pigment-producing microbes from
these oceanic areas, in conjunction with assessing their raw pigment extracts for antimicrobial effectiveness, presents an exciting
frontier for the breakthroughs in antibiotic creation. From ten assorted marine bacterial candidates, eight showed capabilities of pigment biosynthesis; however, only a duo displayed considerable antimicrobial action. Confirmatory analyses of these isolates involved
meticulous biochemical testing methods, while precise identification was done through analysis of the 16S rRNA gene sequence
and subsequent phylogenetic evaluations. Eventually, VSB3 was taxonomically pinpointed as Pseudomonas aeruginosa following indepth molecular scrutiny. Remarkably, the unrefined pigment solution yielded from VSB3 exhibited a strong antibacterial response
against strains such as Bacillus subtilis, Bacillus cereus, and Proteus vulgaris. Manifestly, this inquiry accentuates the auspicious role
of marine-derived bacterial pigments in fostering bioactive substances for industrial innovation and advancing medical treatment
modalities.

The study was based on surveying the occurrence of clinical pathogens in two public health care centers in Vellore. 27 Samples were collected from different areas and were inoculated into nutrient broth immediately and brought to the laboratory for incubation. After successful incubation (24 h) samples were streaked on to nutrient agar plates, which upon incubation showed growth but in order to get isolated pure colonies they were serially diluted, followed by sub culturing on nutrient agar plates which upon further incubation was sub-cultured on nutrient agar slants and on differential media. Various biochemical tests like catalase, oxidase, MRVP, etc. were also performed for the identification of the organisms isolated from public health care sectors. Our main objective was to check different types of pathogens which could be possibly present in a hospital and their resistance towards several different antimicrobials, by conducting antimicrobial susceptibility test. The work was also aimed at determining increased resistance and to identify multi-resistant forms of various pathogens by 16S rRNA sequence method, which is becoming an increased threat to mankind acquired during hospital visits.

CAPÍTULO III-Dinámica espacial y temporal del micro y mesozooplancton 69 Tabla III.3 Lista de especies del microzooplancton detallando los valores absolutos (Prom.) y relativos (%) de abundancia y biomasa para ambos sitios y profundidades estudiadas en caleta Potter. Taxa Sitio 1 Sitio 2 Superficie Fondo Superficie Fondo Abundancia (ind. l-1) Biomasa (µg C l-1) Abundancia (ind. l-1) Biomasa (µg C l-1) Abundancia (ind. l-1) Biomasa (µg C l-1) Abundancia (ind. l-1) Biomasa (µg C l-1) Prom.

Para determinar las variables que permiten predecir la ocurrencia de bacterias (coliformes fecales y totales y estreptococos fecales) en la Bahía de Banderas mediante redes bayesianas se realizaron 21 campañas oceanográficas mensuales en las que se midieron 45 variables, en 21 estaciones de muestreo, de marzo de 2003 a diciembre de 2005. Se separaron los datos en secas y lluvias, se calcularon los percentiles 10, 20, 30, 40, 50, 60, 70, 80 y 90 para cada variable y se crearon matrices con los datos que están dentro de cada uno de los siguientes intervalos: x ≤

, con los objetivos de: 1) identificar y caracterizar los patrones espaciales de diversidad de ciliados y su variación estacional, y 2) evaluar la influencia de factores ambientales sobre la diversidad. Se aplicó un análisis geoestadístico de simulación condicional a los valores de H' (índice de diversidad de Shannon), calculados a partir de muestras recolectadas en 40-45 sitios de la laguna durante las épocas de lluvias y de secas. Las interrelaciones entre la diversidad de ciliados y el ambiente lagunar se evaluaron usando un análisis de componentes principales (ACP). Se identificaron 36 morfoespecies de ciliados pláncticos; H' varió entre 0.08 y 1.9 y se distribuyó en manchones. El ACP indica que la diversidad de ciliados cambió estacionalmente y en función de las características hidrodinámicas derivadas de la apertura y cierre de la boca lagunar. Durante la temporada de lluvias y cuando la barra estuvo abierta, se presentó una mayor heterogeneidad espacial con numerosos manchones de diversidad de menor extensión (1.6 km), en los cuales dominó el ciliado fototrófico Myrionecta rubra. En contraste, en temporada de secas y cuando la boca de la laguna permaneció cerrada, se encontraron dos manchones de diversidad de mayor tamaño (2.7 km), en los que dominaron Lohmanniella oviformis y Tintinnopsis sp. Se discute el impacto sobre las redes tróficas de la distribución en manchones de la diversidad de ciliados.

El bacterioplancton y el ciclo microbiano (microbial loop) desempeñan un papel importante, reciclando nutrientes y viabilizando el flujo de carbono desde la materia orgánica a la cadena trófica clásica. Los factores que regulan el crecimiento bacteriano y su transferencia a niveles tróficos superiores han sido poco estudiados en lagunas amazónicas. Con el objetivo de determinar las tasas de crecimiento bacteriano y las pérdidas por pastoreo, la identidad del nutriente limitante, y las fuentes que sostienen el crecimiento bajo condiciones de limitación, realizamos dos experimentos (períodos de aguas altas y aguas bajas) de dilución/adición selectiva de nutrientes en Laguna La Granja, una laguna localizada en la llanura de inundación del Rio Blanco (Beni, Bolivia). En ambos experimentos el crecimiento bacteriano estuvo limitado por la disponibilidad de nutrientes inorgánicos, el P fue limitante en el experimento del período de aguas altas, mientras que N y P fueron co-limitantes en el experimento del período de aguas bajas. El consumo por el microzooplancton represento prácticamente la totalidad de la producción bacteriana, mientras que los nutrientes reciclados por estos organismos fueron la principal fuente que sostuvo el crecimiento bacteriano bajo condiciones de limitación. Nuestros resultados sugieren que la función de reciclar nutrientes no recae sobre el bacterioplancton, sino sobre el microzooplancton.

The bioavailability and utilization of porphyrin-bound iron, specifically heme, by marine microorganisms have rarely been examined. This study used Ruegeria sp. strain TrichCH4B as a model organism to study heme acquisition by a member of the Roseobacter clade. Analogs of known heme transporter proteins were found within the Ruegeria sp. TrichCH4B genome. The identified heme uptake and utilization system appears to be functional, as the heme genes were upregulated under iron stress, the bacterium could grow on ferricporphyrin complexes as the sole iron source, and internalization of 55 Fe from ferric protoporphyrin IX was observed. The potential ability to utilize heme in the Roseobacter clade appears to be common, as half of the isolates in the RoseoBase database were found to have a complete heme uptake system. A degenerate primer set was designed and successfully used to identify the putative heme oxygenase gene (hmus) in the roseobacter heme uptake system from diverse nonenriched marine environments. This study found that members of the Roseobacter clade are capable of utilizing heme as an iron source and that this capability may be present in all types of marine environments. The results of this study add a new perspective to the current picture of iron cycling in marine systems, whereby relatively refractory intracellular pools of heme-bound iron may be taken up quickly and directly reincorporated into living bacteria without previous degradation or the necessity of a siderophore intermediate.

Previously published data on vertical fluxes of particulate carbon (PC), nitrogen (PN), organisms (MICRO), and extracted adenosine triphosphate (ATP) into screened sediment traps (335/xm) from the VERTEX 5 and ADIOS I programs are reexamined as they relate to biogeochemical cycling and oceanic productivity. The four stations discussed represent an oligotrophic to mesotrophic gradient in total primary production (PT), ranging from 245 to 1141 mg C m-2 d-1 and a gradient in PC flux from the euphotic zone, ranging from 12 to 164 mg C m-2 d-• for particles <335/xm in diameter. Vertical fluxes of PC, PN, MICRO, and ATP decreased as negative power functions of depth with significantly higher depth-dependent losses for ATP fluxes. The flux of intact biota (free, particleassociated, and some active "swimmers," measured microscopically and by extracted ATP) decreased rapidly in the upper 200 m, contributing as much as 52.4% at the most productive station and as little as 1.6% to the flux of PC at oligotrophic stations, remaining relatively constant or increasing slightly (to 3.4-9.6% PC flux) between 200 and 2000 m. Multiple regression analyses, expressing fluxes as • Now at Marine Sciences Research Center, State University of New York at Stony Brook.

AlgaeBase has been under construction since 1996, initially as a database of the seaweeds of the northeastern Atlantic for private use as an aide-mémoire. It was extended to the Mediterranean as part of an EU project. Initially programmed in FileMaker, the database was put on line in 1998, but it quickly became apparent that the internet demand for such information outstripped the capabilities of this software. In 2004, it was completely reprogrammed in MySQL, and named AlgaeBase. Although all Irish public funding abruptly ceased in 2008, we have managed to keep the data on-line. In 2012, sponsorship from Ocean Harvest, an Irish company, was received and this will allow us to continue for the present. AlgaeBase was intended to be an information source on the taxonomy and distribution of all algae, but it quickly became apparent that taxonomy is inseparable from nomenclature and we have been greatly assisted in this by having on-line access to the cards of Paul Silva"s Index Nominum Algarum. In recent years, we have put a lot of effort into adding PDFs of publications. In this we have been somewhat thwarted by the legal aspects of copyright; technically, we cannot offer PDFs of works before 1923. Nevertheless, we have managed to make available over 5,000 PDFs, many of rare and beautiful items found only in a handful of major libraries worldwide. Another issue is that of the legal requirements of the International Code of Nomenclature for Algae, Fungi, and Plants. Most problematical of all is the provision in Art. 13 for later-startingpoint dates for the families Nostocaceae, Desmidiaceae, and Oedogoniaceae (each in the original sense of defined publications). Many authors have seen fit to ignore these provisions. This is not the only article of the Code ignored by authors: many names published are invalid for reasons that some clearly regard as insignificant, or in ignorance of the requirements. In recent years, high-impact on-line journals in particular often completely ignore the necessities of the Code. Some of the conventions of taxonomy are also disregarded by authors; for example, the requirement for considering a genus taxonomically in terms of its type species. The considerable extent of this problem is evident in the number of genera that still have no type species designated, although some authors seem to have no issues with describing a new entity without even mentioning its type. Some recent taxonomic proposals are also invalid as the entity proposed included the type of another name. The proverb "Homo proponit, sed Deus disponit" can be applied to taxonomy in that one may be free to make any taxonomic proposals one wishes (provided somebody will publish them validly), but the final arbiter of acceptance is usually some authoritative source that surpasses all others. Essentially, like all the sciences, taxonomy is a web of hypotheses, the acceptance of which is based on the quality of the arguments presented. Unfortunately, AlgaeBase has, for some groups, become such an authoritative source for nomenclatural and taxonomic matters, which it was never intended to be. News from Antarctica: another group of microalgal strains divorce the old genus Scenedesmus (Scenedesmaceae, Chlorophyta

La contribucion del bacterioplancton (BP) a la trama trofica planctonica, asi como los factores ambientales y biologicos involucrados en su control, son poco explorados en ambientes de alta montana de las regiones tropicales. En el Embalse del Neusa, un sistema altoandino colombiano, se evaluo la dinamica espacio-temporal de la densidad, biovolumen y biomasa del BP y su relacion con la variabilidad ambiental y la densidad de nanoplancton autotrofo (NA) y los nanoflagelados heterotrofos (NFH). No se registro una asociacion clara entre la dinamica del BP y los nutrientes. Sin embargo, esta relacion parecio ser indirecta a traves de la estimulacion de la produccion del NA durante los periodos de mezcla y mayor precipitacion de lluvia. Las mayores abundancias y biomasas de BP se detectaron en la estacion litoral en coherencia con bajos numeros de NFH y posibles aportes organicos derivados de las macrofitas. El contenido total de carbono y el biovolumen promedio del BP se correlacionaron...

Vertical and seasonal distribution of the biogeochemical tracer N* was estimated to delineate the key pathways that regulate nitrogen in the Alfonso Basin, Bay of La Paz, between February 2012 - March 2013. We used data of dissolved inorganic nitrogen (DIN) and phosphorus (DIP) concentrations from four levels in the euphotic zone (100, 33, 3, and 0.1% I0) and another four depths below it (150, 200, 250 and 300 m). For the calculation of N*, its constants were reestimated from the original equation based on historical data of nutrients compiled between December 2005 - December 2012. Detection of anomalies on the mean ratio of NID:DIP (13.16) indicated a predominance of negative values corresponding to a greater removal of NID, especially below the 150 m, under hypoxic conditions (&lt; 1.4 ml l-1) and during periods of high biological production for the area. The incidence of these values could be associated to the local denitrification process, as well as advection of water masses fr...

Transparent exopolymer particles (TEP) have been reported as a significant fraction of organic microgels in different oceans. No TEP data have been published for the California Current region off Baja California that indicate the potential contribution of this reservoir to the carbon budget. We measured TEP in seawater samples, using the spectrophotometric method with alcian blue stain, and additional environmental and biological variables during 3 seasons at coastal stations between ~1.4 and 12.0 mi offshore, near 31ºN. Concentrations of TEP obtained with 0.45 µm pore size filters showed spatial and temporal distributions with a tendency to increase from offshore to nearshore and from winter to summer, respectively, ranging from undetectable values to 7.18 µg XG eq·mL–1 (median: 0.70). A significant positive correlation was observed between the concentration of TEP and bacterioplankton abundance (P &lt; 0.05), and between total organic carbon and bacterioplankton abundance (P &lt; ...

The aim of this study was to determine the composition and antimicrobial effect of Helichrysumarenarium L. essential oil in “in-vitro” condition. For this purpose, the chemical composition of the essential oil which obtained by hydro-distillation was examined by GC/MS and the antimicrobial effectwas studied on the growth of threefood born pathogens including Serratiamarcescens, Streptococcus agalactiae and Staphylococcus aureus using micro-dilution method. The minimum inhibitory concentration (MIC) andminimumbactericidalwere determined for the essential oil at ten concentrations. Chemical composition analysis of the essential oil identified a total of 38 compounds. Themain components of essential oilwere a-pinene (32%), 1,8-cineole (16%), a-humulene (15%), â-caryophyllene (8%). Other separated components accounted for less than 29% of the oil. Results of antimicrobial analysis showed MIC values of 406, 812 and 812µg/ml respectively for Serratiamarcescens, Streptococcus agalactia...

Los fertilizantes y residuos ganaderos contaminan los acuíferos con nitratos (NO3-). En estos escenarios se pueden analizar los isótopos 15 N y 18 O del mismo como herramienta para discriminar dichas fuentes. El objetivo es identificar el origen de la contaminación a través de características geoquímicas del agua y del uso de los isótopos del NO3en esta cuenca de llanura del Sur de Córdoba. Los valores de NO3hallados (3,0 a 192,5 mg/L), superan en su mayoría el valor característico de fondo natural de la zona (7,5 mg/L), y sumado al aporte de otros iones detectados, se evidencia la contaminación del acuífero. Los valores isotópicos de muestras seleccionadas dieron δ 15 N de +6,39‰ a +12,33‰ y δ 18 O de +2,04‰ a +7,96‰. Los NO3habrían sufrido enriquecimiento isotópico principalmente por desnitrificación (verificada por εN/εO de 1,5), que los desplaza de los campos asignados para cada fuente y que dificulta su discriminación.

Macroalgal blooms may lead to dramatic changes in physicochemical variables and biogeochemical cycling in affected waters. However, little is known about the effects of macroalgal blooms on marine bacteria, especially those functioning in nutrient cycles. We measured environmental factors and investigated bacterial diazotrophs in two niches, surface waters that were covered (CC) and non-covered (CF) with massive macroalgal canopies of Ulva prolifera, in the Yellow Sea in the summer of 2011 using real-time PCR and clone library analysis of nifH genes. We found that heterotrophic diazotrophs (Gammaproteobacteria) dominated the communities and were mostly represented by Vibrio-related phylotypes in both CC and CF. Desulfovibrio-related phylotypes were only detected in CC. There were significant differences in community composition in these two environments (p < 0.001) and a much higher abundance of nifH in CC (4.55 Â 10 6 copies l À1) than in CF (2.49 Â 10 6 copies l À1). The nifH copy number was inversely related to concentrations of ammonium and dissolved inorganic nitrogen and to the stoichiometric ratios of N:P and N:Si. This indicates that macroalgal blooms significantly affect diazotrophic abundance and community composition and that vibrios and Desulfovibrio-related heterotrophic diazotrophs adapt well to the (N-rich but P-limited) environment during blooming. Potential ecological and microbiological mechanisms behind this scenario are discussed.

The relative abundances of nitrifying, denitrifying and anammox prokaryotes in sediments of three hyper‐nutrified estuarine tidal flats of Laizhou Bay, Bohai Sea, China were investigated. Quantitative PCR estimates indicated that in most cases archaeal (AOA) amoA genes were more abundant than bacterial (AOB) amoA genes, and ratio of AOA/AOB was correlated with pH, Cd, and Cu. Of the denitrifiers, nirK‐type outnumbered nirS‐type, with nosZ‐type being the lowest. Variation of the ratio between nirK and nirS abundance depends on pH, nitrite, nitrate, and Cd. The combination of (nirS + nirK‐nosZ), an indicator of genetic potentials for N2O emission, was only related to the temperature. Anammox bacterial 16S rRNA gene abundances were correlated with salinity, pH, nitrite, and Cu. In contrast, the contribution of anammox to N2 production, by using anammox bacterial 16S rRNA/nosZ ratio as a proxy, was correlated to temperature, ammonium and dissolved oxygen in the overlying water, ratio of...

Microbial Fe-oxidation has been mainly studied at deep-sea hydrothermal vents because the low concentration of oxygen and high concentration of ferrous ion was preferable for Fe-oxidizing bacteria that have to compete with abiotic Fe-Oxidation. However, microbial Fe-oxidization in shallow, fully oxygenated environments has been still largely unknown. In this study, we aim to reveal the ecology and role for mound formation of Fe-oxidizing bacteria at iron oxyhydroxide-rich hydrothermal mounds developing in Nagahama Bay, Satsuma-Iwojima where we observed dense assembly of twisted stalks, typical signature of microbial Fe-oxidation. Core samples were taken from the iron oxyhydroxide-rish mound and used for sequencing and microscopic analysis. Microscopic observation indicated the highest occurrence of stalk structure was observed at around 20 cm from the surface. Sequencing of 16S rRNA gene of prokaryotic communities ( &gt;100,000 reads/sample) revealed that Anaerolineae known as oblig...

La tasa de decaimiento (k) de los colifagos PRD1 y MS2, modelos de virus entéricos, fue evaluada in situ en el agua de la presa recreativa "La Juventud" ubicada en Marín, N.L., México. Su relación con la temperatura (T), pH, conductividad eléctrica (CE), sólidos suspendidos totales (SST), oxígeno disuelto (OD) y coliformes totales (CT) y fecales (CF) fue también analizada. Los resultados mostraron que para ambos colifagos la menor sobrevivencia fue en verano y la mayor en invierno. Comparado con PRD1, MS2 presentó mayor tasa de decaimiento. Sin embargo, PRD1 sobrevivió por más tiempo en el fondo de la columna de agua de la presa que en su superficie. La tasa de decaimiento no estuvo relacionada con la CE ó la concentración de OD medida en cada uno de los sitios de muestreo. La concentración de SST fluctuó entre 45 y 80 mg/L, CT entre 75 y 335 unidades formadoras de colonias (UFC)/100 mL, mientras que la densidad de CF se ubicó entre 25 y 125 UFC/100 mL de muestra. Estos valores están muy por debajo de los máximos permisibles para descargas de aguas residuales a aguas y bienes nacionales, cumpliendo con las normas mexicanas para aguas de recreación en SST y CF.

Coastal upwelling areas are highly productive marine systems in which the development of oxygen-depleted conditions and the availability of diverse electron donors (e.g., organic matter, NH z 4 , H 2 S) favor the processes involved in nitrogen (N) loss. We characterize the temporal and vertical variability of anammox and denitrification over the continental shelf off central Chile (36.5uS), through 15 N and 13 C tracer experiments, including amendments with H 2 S and S 2 O 2{ 3 along with measurements of 15 N 2 and 15 N 2 O production and oceanographic variables during a year (2009 to 2010). Restricted to the bottom waters, both anammox and denitrification contributed similarly (, 500 nmol N 2 L 21 d 21) to N loss during spring, while a marked decrease in the activity of these processes occurred in summer (103 and 14 nmol N 2 L 21 d 21 for anammox and denitrification, respectively). During fall, denitrification was the only contributor to the observed nitrogen deficit (894 nmol N 2 L 21 d 21). Interestingly, a substantial increase in the rates of denitrification (, 1200 nmol N 2 L 21 d 21) and dark 13 C assimilation were observed after the addition of H 2 S, indicating an autotrophic contribution to denitrification, which could be fueled in situ by H 2 S emitted from sediments or produced in the water column. The observed patterns seem to be controlled (stimulated or inhibited) by the availability of oxygen, organic matter, and H 2 S. This study establishes the magnitude and co-occurrence of the different processes responsible for N removal in the coastal upwelling system of central Chile. This linkage of the nitrogen, carbon, and sulfur cycles is relevant to a global climate change scenario.

RESUMEN Seis puntos de muestreos localizados en el Lago Gatún y circundantes a la Isla de Barro Colorado, se escogieron para objeto de estudio durante un período de siete meses (enero-julio de 1998), para conocer los parámetros físico-químicos y biológicos, teniendo en consideración la influencia de la temporada seca y lluviosa. Se realizaron análisis estadístico de las muestras para determinar la posible relación de la abundancia y biomasa macrobentónica entre el carbono orgánico total en el sedimento (COT), el oxígeno disuelto (OD) y la composición de los sedimentos. Así mismo se trató de determinar la relación de la dinámica del plancton con los parámetros físico-químicos (temperatura, oxígeno disuelto, fosfato y la profundidad). Los parámetros físico-químicos durante todo el período de estudio mostraron variaciones y pequeños cambios significativos para todas las estaciones. Se observaron incrementos de los niveles de fosfatos y del carbono orgánico total de los sedimentos duran...

Microorganisms are able to synthesize secondary metabolites of various structures and bioactivities. These metabolites are produced to help the organism compete successfully with other organisms in their natural habitat and adapt with changing environmental milieu. The ability of rhizosphere bacteria (Bacillus subtilis NC_000964.3 and Pseudomonas aeruginosa NC_002516.2) isolated from the rhizospheric soil of Manatee food plants Mimosa pygra, Ipomeoa aquatica and Pistia stratoites to inhibit the growth of human pathogens (P. aeruginosa, E. coli, S. aureus and B. subtilis) was evaluated using standard methods. It was observed that the growth extracts of B. subtilis strains M 5 , M 8 and P 7 and P. aeruginosa strains I 3 and M 9 contained useful bioactive compound. GC-MS analysis of the cell-free methanol extract of the antibiotic producing bacterial strains was also evaluated and the results showed that their inhibitory potentials against bacterial pathogens are due to the presence of phenylethyl alcohol, 2-ethyl-4-methyl-1,3-dioxolane, bicyclo [4.2.0] octa-1,3,5-triene and 4-amino-2-methyl-5,6-dimethyl pyrimidine for B. subtilis and 3,4-dimethyl tetrahydrofuran, 4,6-dimethyl-4-hydroxy-5heptenoic acid and 2,4-dimethyl-4-heptanol for Pseudomonas aeruginosa. These strains of rhizosphere bacteria may be exploited to produce new antibiotics.

We examine how oxygen levels and the choice of 16S ribosomal RNA (rRNA) tags impact marine bacterial communities using Next-Generation amplicon sequencing. Analyzing V3 and V6 regions, we assess microbial composition in both Oxygen minimum zones (OMZ) and non-OMZ (NOMZ) areas in the Arabian Sea (AS) and the Central Indian Ocean basin (CIOB) respectively. Operational taxonomic units (OTUs) at 97% similarity showed slightly higher richness and diversity with V6 compared to V3. Vertical diversity patterns were consistent across both regions. NOMZ showed greater richness and diversity than OMZ. AS and CIOB exhibited significant differences in bacterial community, diversity, and relative abundance at the order and family levels. Alteromonadaceae dominated the OMZ, while Pelagibacteraceae dominated the NOMZ. Synechococcaceae were found exclusively at 250 m in OMZ. Bacteria putatively involved in nitrification, denitrification, and sulfurylation were detected at both sites. Dissolved oxygen significantly influenced microbial diversity at both sites, while seasonal environmental parameters affected diversity consistently, with no observed temporal variation.

Con el propósito de estimar la productividad primaria del fitoplancton mediante el método de oxígeno disuelto (AO,) con diferentes tiempos de incubación y compararlo con la estimada mediante el método de carbono catorce ('"C), se realizaron simultáneamente experimentos de productividad primaria con ambos métodos, los días 12 de noviembre de 1993, 3 y 16 de febrero de 1994, y 24 de mayo de 1994. La productividad primaria bruta (PPB) estimada por el método de AO, fue similar a los valores derivados por el método de '"C, con a = 0.05. Además, para conocer la variabilidad de la concentración de clorofila y abundancia bacteriana, se recolectó agua de mar cada 30 min durante el periodo de muestreo. Se concluye que, debido a su abundancia, es importante considerar las bacterias en estudios encaminados a estimar la productividad primaria en cuerpos costeros, ya que afectan el resultado del método de AOZ, por la utilización del oxígeno por parte de las bacterias cuando hay suficiente sustrato dentro de las botellas. Los valores de la PPB estimada con el método de AO, pueden ser recomendadas como una alternativa viable al método de 14C para situaciones donde no es conveniente o posible el uso de isótopos radioactivos, siempre y cuando se realicen los experimentos con réplicas y por lo menos con tres tiempos finales de incubación.

The intestinal microenvironment of bacteria in fish influences the host in many ways, including the metabolism of several nutrients. Isolation, enzymatic activities, and molecular identification of culturable bacteria associated with the gastrointestinal tract of rabbitfish, Siganus guttatus Bloch, were investigated in the present study. Occurrence and distribution of enzyme-producing bacteria in the proximal (PI), middle (MI), and distal (DI) gut segments were determined and data were presented as log viable counts g-1 intestine (LVC). The heterotrophic bacterial population (LVC = 6.95) as well as the amylolytic, proteolytic, cellulolytic, and carrageenolytic populations had the highest occurrence in the DI region (LVC = 5.73, 5.46, 3.21 and 5.00, respectively). The isolates were qualitatively screened on the basis of their extracellular enzyme producing ability. The selected strains were further quantitatively assayed for amylase, protease, and cellulase activities. Results of enz...

Se analizó la distribución vertical y la contribución de las fracciones bacterioplanctónica, nanoplanctónica y microzooplanctónica a la biomasa menor de 200 µm en las aguas oceánicas adyacentes a Cuba. Las muestras fueron obtenidas en los niveles de superficie, termoclina y final de la capa fótica en estaciones con diferente nivel de riqueza y en dos épocas del año (lluvia y seca). Las biomasas de las fracciones fueron calculadas por métodos estándar, incluyendo conteo celular y microscopía de epifluorescencia. Las aguas oceánicas al norte mostraron valores de biomasa superiores a los del sur en la época de lluvia con relación a la de seca. Las estaciones oceánicas (S 88 y N 18) presentaron, en general, biomasas menores que las encontradas en las estaciones con influencia costera (S 37 y N 57) para las tres fracciones analizadas. En las aguas oceánicas al norte, el nanoplancton y el microzooplancton fueron los que más contribuyeron a la biomasa < 200 µm en la capa fótica. En contraste, en las aguas oceánicas al sur, el bacterioplancton fue el mayor contribuyente a la biomasa < de 200 µm.

R������. Las concentraciones naturales de fósforo y nitrógeno en las lagunas pampeanas permiten el desarrollo de densas praderas de vegetación acuática sumergida, el dominio de fitoplancton o plantas acuáticas flotantes. En las últimas décadas, la eutrofización de las lagunas aumentó con el avance de labores agrícolas, fertilización de campos y el stock ganadero. La turbidez que producen las floraciones fitoplanctónicas inhibe el crecimiento de macrófitas sumergidas y el fitoplancton domina. Este es el caso de la laguna de Lobos, que por más de 20 años se mantuvo como una laguna turbia orgánica con predominio de cianobacterias. Estudiar el metabolismo ecosistémico aporta gran información sobre el modo en que el estado trófico de la laguna contribuye a la producción, respiración y metabolismo neto, con posibles consecuencias para la biota acuática. Aquí presentamos una evaluación del metabolismo en esta laguna a partir de los cambios en la concentración de oxígeno disuelto, estimado para otoño y primavera. La producción bruta de la laguna fue menor y menos variable en otoño (1.57±1.33 g O 2 .m-2 .día-1) que en primavera (20.45±18.00 g O 2 .m-2 .día-1). Si bien la producción fue alta durante el día, la respiración también fue elevada-incluso, la superó-sobre todo en primavera, cuando fue mayor la densidad de organismos planctónicos, principalmente cianobacterias. Por ello, el metabolismo neto tuvo valores bajos o negativos. Esta situación de gran consumo de oxígeno se acentuó en el período de mayor temperatura y de menor profundidad de la laguna, que coincide con la mayor concentración de clorofila-a y de material particulado, y la menor transparencia del agua. Concluimos que la laguna fue predominantemente heterotrófica durante el período que duró el estudio. De mantenerse las altas concentraciones de nutrientes es probable que aumenten los factores que producen estrés y sus consecuencias negativas para la fauna acuática. [Palabras clave: laguna turbia orgánica, fitoplancton, eutrofización, producción primaria, respiración y oxígeno disuelto] A�������. Environmental factors conditioning the metabolism of a Pampean shallow lake. Pampean shallow lakes naturally have water nitrogen and phosphorous concentrations that allow the development of dense beds of submerged aquatic vegetation, phytoplankton, or free-floating aquatic plants. In recent years, the eutrophication of these shallow lakes has increased due to the intensification of agriculture, use of fertilization and livestock. Phytoplankton-induced turbidity inhibits the growth of the submerged aquatic vegetation leading to phytoplankton dominance. This is the case of the Lobos shallow lake, which in a period greater than 20 years has remained as an organic turbid shallow lake, with cyanobacteria dominance. The study of the ecosystem metabolism can give relevant information about how the trophic state of a shallow lake drives production, respiration and net metabolism, and the potential consequences for aquatic biota. We evaluated the Lobos shallow lake metabolism using diel changes in dissolved oxygen concentrations during autumn and spring. Gross primary production showed lower values and variability in Autumn (1.57±1.33 g O 2 .m-2 .day-1) than in Spring (20.45±18.00 g O 2 .m-2 .day-1). Although there was high production during the day, respiration was also high, especially in Spring, where there was higher density of planktonic organisms principally cyanobacteria, exceeding net production in both seasons. Thus, we found mainly low or negative values for the net metabolism in Lobos shallow lake. A high oxygen consumption occurred during spring and at the lowest depth, coinciding with the highest chlorophyll-a concentrations, particulate ma�er, and lowest water transparency. We conclude that Lobos shallow lake was predominantly heterotrophic during study period. High nutrient concentrations will likely increase the factors that produce stress and negative impacts on aquatic fauna.

The fecal indicator organism (FIO) Escherichia coli is frequently used as a general indicator of sewage contamination and for evaluating the success of shellfish cleaning (depuration) processes. To evaluate the robustness of this approach, the accumulation, retention, and depuration of non-pathogenic E. coli, pathogenic E. coli O157:H7 and norovirus GII (NoV GII) RNA were evaluated using a combination of culture-based (E. coli) and molecular methods (E. coli, NoV GII) after exposure of mussels (Mytilus edulis) to water contaminated with human feces. We simulated water contamination after a point-source release from a combined sewer overflow (CSO) where untreated wastewater is released directly into the coastal zone. All three microbiological indicators accumulated rapidly in the mussels, reaching close to maximum concentration within 3 h of exposure, demonstrating that short CSO discharges pose an immediate threat to shellfish harvesting areas. Depuration (72 h) in clean water proved partially successful at removing both pathogenic and non-pathogenic E. coli from shellfish tissue, but failed to eradicate NoV GII RNA. We conclude that current EU standards for evaluating microbiological risk in shellfish are inadequate for protecting consumers against exposure to human norovirus GII found in polluted marine waters.

The fecal indicator organism (FIO) Escherichia coli is frequently used as a general indicator of sewage contamination and for evaluating the success of shellfish cleaning (depuration) processes. To evaluate the robustness of this approach, the accumulation, retention, and depuration of non-pathogenic E. coli, pathogenic E. coli O157:H7 and norovirus GII (NoV GII) RNA were evaluated using a combination of culture-based (E. coli) and molecular methods (E. coli, NoV GII) after exposure of mussels (Mytilus edulis) to water contaminated with human feces. We simulated water contamination after a point-source release from a combined sewer overflow (CSO) where untreated wastewater is released directly into the coastal zone. All three microbiological indicators accumulated rapidly in the mussels, reaching close to maximum concentration within 3 h of exposure, demonstrating that short CSO discharges pose an immediate threat to shellfish harvesting areas. Depuration (72 h) in clean water prove...

Climate change causes droughts, which in turn cause significant physiological stress for soil microorganisms. In this study, we investigated how the abundance of total bacterial, crenarchaeal and fungal communities and the abundance of N-cycling microbial guilds responded to a severe agricultural drought event in a long-term experiment of minimum tillage (MT) and conventional ploughing (CT) at two soil depths. Drought, defined as a reduction of soil water content and increased soil temperature, significantly decreased the abundance of all the studied microbial communities. The data showed linear relationships between all dependent variables and soil water content and soil temperature for the examined range of soil water content (WHC 13-76%) and examined range of average daily soil temperature at 5 cm depth (17-30°C). Thus, we found that the abundance of most studied microbial communities decreased by about 2% when water content decreased by 1 mass % and by about 10% when temperature increases by 1°C. When comparing communities at average soil water content and average soil temperature, MT had higher average abundances of total bacterial and crenarchaeal 16S rRNA and fungal ITS genes in the 0-10 cm soil layer than did CT (1.9, 2.9 and 2.5 times, respectively), as well as AOA and AOB amoA (3.9 and 1.7 times, respectively), nirK, nirS, nosZI and nosZII genes (2.0, 1.8, 1.8 and 2.3 times, respectively); while significant differences between MT and CT in the 10-20 cm soil layer were found only in the average abundance of crenarchaeal 16S rRNA and crenarchaeal amoA genes (3.5 and 2.7 times greater under MT than CT). Regardless of the weather conditions during our study, the abundances of all communities were greater under MT 0-10 than under CT 0-10. After three weeks of severe drought, the greatest decrease in the abundance of all communities, bacterial and archaeal N-cycling guilds as well as total prokaryotes and fungi, was observed under MT 0-10. However, after only a few rainfall events, all communities under both tillage systems reached their initial abundance, demonstrating a high resilience.