Extracellular enzymes

High elevation subnival-zone soils are increasing in spatial extent in the Himalayas due to glacial retreat and grazing pressures. These seemingly barren soils actually harbor significant microbial diversity but have remained mostly unstudied in all of the major mountain ranges of the Earth. Here we describe a preliminary survey of subnival-zone soils and one vegetated high-elevation soil in the Annapurna and Sagarmatha regions of the Nepalese Himalayas. We examined microbial biomass and activity as well as key microclimatic and edaphic variables that may control microbial activity in these soils. Microbial biomass carbon levels were the lowest ever reported for any soil to date, whereas microbial nitrogen and soil enzyme activities were similar to levels measured in previous studies of subnival-zone soils of Peru and Colorado. Our initial studies also indicate that soil water availability is the primary limiting factor for life in these high-elevation soils. Key words: Microbial; s...

Agronomic practices such as crop residue return and additional nutrient supply are recommended to increase soil organic carbon (SOC) in arable farmlands. However, changes in the priming effect (PE) on native SOC mineralization in response to integrated inputs of residue and nutrients are not fully known. This knowledge gap along with a lack of understanding of microbial mechanisms hinders the ability to constrain models and to reduce the uncertainty to predict carbon (C) sequestration potential. Using a C-labeled wheat residue, this 126-day incubation study examined the dominant microbial mechanisms that underpin the PE response to inputs of wheat residue and nutrients (nitrogen, phosphorus and sulfur) in two contrasting soils. The residue input caused positive PE through "co-metabolism," supported by increased microbial biomass, C and nitrogen (N) extracellular enzyme activities (EEAs), and gene abundance of certain microbial taxa (Eubacteria, β-Proteobacteria, Acidobacte...

The genus Chaetomium is a frequently occurring fungal taxon world-wide. Chaetomium and Chaetomium-like species occur in indoor environments, where they can degrade cellulose-based building materials, thereby causing structural damage. Furthermore, several species of this genus may also cause adverse effects on human health. The aims of this research were to identify Chaetomium and Chaetomium-like strains isolated from indoor environments in Hungary and Finland, two geographically distant regions of Europe with drier and wetter continental climates, respectively, and to study their morphological and physiological properties, as well as their extracellular enzyme activities, thereby comparing the Chaetomium and Chaetomium-like species isolated from these two different regions of Europe and their properties. Chaetomium and Chaetomium-like strains were isolated from flats and offices in Hungary, as well as from schools, flats, and offices in Finland. Fragments of the translation elongat...

The biological function(s) of the cpkk1, cpkk2 and cpkk3 genes, encoding the three mitogen-activated protein kinase kinases (MAP2Ks) of Cryphonectria parasitica, the causal agent of chestnut blight, were examined through knockout strains. Cpkk1, the Mkk1 orthologue, acts in a phosphorylation cascade essential for cell integrity; Cpkk2 is the Ste7 orthologue involved in the pheromone response pathway; Cpkk3 is the Pbs2 orthologue, the MAP2K activated during the high-osmolarity response. Our analysis confirmed the role of each MAP2K in its respective signalling cascade with some peculiarities: abnormal hyphae with a reduced number of septa and thinner cell walls were observed in Δcpkk1 mutants, and a strong growth defect on solid media was evident in Δcpkk2 mutants, when compared with the controls. Virulence on chestnut was affected in both the Δcpkk1 and Δcpkk2 strains, which were also unable to complete the developmental steps essential for mating. No alterations were reported in Δcpkk3, except under hyperosmotic conditions and in the presence of fludioxonil. Δcpkk2 mutants, however, showed higher sensitivity during growth in medium containing the antibiotic G418 (Geneticin).

The biological function(s) of the cpkk1, cpkk2 and cpkk3 genes, encoding the three mitogen-activated protein kinase kinases (MAP2Ks) of Cryphonectria parasitica, the causal agent of chestnut blight, were examined through knockout strains. Cpkk1, the Mkk1 orthologue, acts in a phosphorylation cascade essential for cell integrity; Cpkk2 is the Ste7 orthologue involved in the pheromone response pathway; Cpkk3 is the Pbs2 orthologue, the MAP2K activated during the high-osmolarity response. Our analysis confirmed the role of each MAP2K in its respective signalling cascade with some peculiarities: abnormal hyphae with a reduced number of septa and thinner cell walls were observed in Δcpkk1 mutants, and a strong growth defect on solid media was evident in Δcpkk2 mutants, when compared with the controls. Virulence on chestnut was affected in both the Δcpkk1 and Δcpkk2 strains, which were also unable to complete the developmental steps essential for mating. No alterations were reported in Δcpkk3, except under hyperosmotic conditions and in the presence of fludioxonil. Δcpkk2 mutants, however, showed higher sensitivity during growth in medium containing the antibiotic G418 (Geneticin).

Prescribed burning and thinning were implemented in an Alabama forest (Bankhead National Forest) as a management strategy to control pest and disease outbreaks and also to increase forest productivity. However, using fire as a control mechanism in this forest may alter soil nutrient cycling, soil organic matter (SOM), and soil microbial populations. There is the need for continuous research on forest ecosystems to bridge knowledge gaps in our understanding of SOM transformations and microbial processes in a repeatedly burned forest ecosystems. The objectives of this study were to assess and document the impact of prescribed burning and thinning on soil labile organic matter fractions, microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN), potential carbon mineralized (PCM), enzymatic activity, and energy (ATP) potentials. Labile organic carbon was isolated using the density method, whereas enzyme activities were determined as described in Bottomley et al. (Methods of s...

Prescribed burning and thinning were implemented in an Alabama forest (Bankhead National Forest) as a management strategy to control pest and disease outbreaks and also to increase forest productivity. However, using fire as a control mechanism in this forest may alter soil nutrient cycling, soil organic matter (SOM), and soil microbial populations. There is the need for continuous research on forest ecosystems to bridge knowledge gaps in our understanding of SOM transformations and microbial processes in a repeatedly burned forest ecosystems. The objectives of this study were to assess and document the impact of prescribed burning and thinning on soil labile organic matter fractions, microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN), potential carbon mineralized (PCM), enzymatic activity, and energy (ATP) potentials. Labile organic carbon was isolated using the density method, whereas enzyme activities were determined as described in Bottomley et al. (Methods of s...

One of the requirements for advancement of nanotechnology are the development of reliable experimental protocols for the synthesis of nanomaterials over a range of biological compositions, sizes and high monodispersity. An attractive possibility of green nanotechnology is to use micro-organisms in the synthesis of nanoparticles. Recently, the utilization of biological systems, especially fungi, has emerged as a novel method for the synthesis of nanoparticles. Nanoparticles are considered as fundamental molecular building blocks for nanotechnology. They are the starting points for preparing many nanostructured materials and devices. In this paper we report the extracellular biosynthesis of silver nanoparticles (AgNPs) by using a fungus named Trichoderma Reesei (also known as Hypocrea jecorina). In the biosynthesis of AgNPs by this fungus, the fungus mycelium is exposed to the silver nitrate solution. That prompts the fungus to produce enzymes and metabolites for its own survival. In this process the toxic Ag+ ions are reduced to the nonetoxic metallic AgNPs through the catalytic effect of the extracellular enzyme and metabolites of the fungus. Absorption UV-Visible light spectroscopy is used to follow up with the reaction process. Fluorescence emission spectroscopy is used to produce detailed information on the progress of reduction of silver nitrate (formation of silver nanoparticles) on the nanosecond timescale. Fourier transform infrared spectroscopy is used for quantitative analyses of the reaction products. Our measurements indicate that extracellular biosynthesis of AgNPs by Trichoderma reesei produces AgNPs with the diameters in the range of 5-50 nm. Trichoderma Reesei is an environmentally friendly fungus, and it is well known for its formation of extracellular enzyme and metabolites in very large amounts, much higher than other fungi. The present process is an excellent candidate for industrial scale production of silver nanoparticles.

Chemical changes in leaf input to forest soils have been reported to affect decay processes. In this work, litter mass loss and decomposition constants (k) during 200 days in solid-state fermentation of the native tree Celtis tala Gill. ex Planch. and the exotic one Ligustrum lucidum Ait. with three common litter saprotrophic basidiomycetes were compared. Alterations in litter quality were characterized by solid-state13C NMR spectroscopy, pH, soluble sugars, ammonium, proteins, and phenol content determination and were associated with extracellular lignocellulolytic enzyme production. Differences in substrate decomposition related to litter type were observed for Leratiomyces ceres, achieving a higher k in the exotic L. lucidum litter, which might be attributed to the induction of manganese peroxidase activity. Substrate preference for alkyl C and more degradation of lignified compounds were found in such substrates. Although no statistical differences in mass loss were observed for...

In the Northern Adriatic Sea, extracellular enzymatic activity was measured during a Lagrangian study following a drifting buoy for 40 h. Dissolved free enzymatic activity represented 20 to 70% of total activity depending on the type of enzyme. a-and P-glucosidases exhibited a significantly higher free activity than proteolytic enzymes. In subsequent laboratory experiments we investigated the effect of zooplankton on the free enzyme pool. The 4-step approach included: ( l ) determinatlon of the enzymatic activities in copepods (mainly Acartia clausi); (2) enzymat~c activity in fecal pellets; (3) short-and long-term grazing experiments; and (4) degradab~lity of free glucosidase in seawater. aand P-glucosidases, leu-aminopeptidase, lipase and chitinase were examined. Experiments in which zooplankton were selectively enriched revealed a significant increase in both particle-bound (due to the increase of bacterial density) and dissolved free enzymatic activity. Incubating water enriched in free enzymes released by zooplankton with natural bacterial consortia, we found that 70% of the original aand P-glucosidase activity remained after 22 h. The presence of microorganisms did not enhance the degradation of these enzymes as compared to autoclaved controls. We found that a considerable amount of free dissolved enzymes is lost by 0.2 pm filtration using Nuclepore filters, thereby leading to an underestimation of dissolved enzymes by -30% in our experiments. Based on our results we conclude that mesozooplankton contribute to the free enzymatic activity in natural waters especially during periods of high grazing activity.

The distribution of extracellular enzyme activities in particle-size fractions of sediments was investigated in a subtropical mangrove ecosystem. Five enzymes involved in carbon (C), nitrogen (N), and phosphorus (P) cycling were analyzed in the sand, silt, and clay of sediments. Among these fractions, the highest activities of phenol oxidase (PHO), β-D-glucosidase (GLU), and N-acetyl-glucosiminidase (NAG) were found in sand, and greater than bulk sediments of both intertidal zone (IZ) and mangrove forest (MG). This result implied that sand fractions might protect selective enzymes through the adsorption without affecting their activities. Additionally, the enzyme-based resource allocation in various particle-size fractions demonstrated that nutrients availability varied with different particle-size fractions and only sand fraction of MG with highest total C showed high N and P availability among fractions. Besides, the analysis between elemental contents and enzyme activities in par...

The diversity of yeasts collected from different sites in Antarctica (Admiralty Bay, King George Island and Port Foster Bay and Deception Island) and their ability to produce extracellular enzymes and mycosporines were studied. Samples were collected during the austral summer season, between November 2006 and January 2007, from the rhizosphere of Deschampsia antarctica, ornithogenic (penguin guano) soil, soil, marine and lake sediments, marine water and freshwater from lakes. A total of 89 isolates belonging to the following genera were recovered:

Atmospheric CO 2 and O 3 concentrations are increasing due to human activity and both trace gases have the potential to alter C cycling in forest ecosystems. Because soil microorganisms depend on plant litter as a source of energy for metabolism, changes in the amount or the biochemistry of plant litter produced under elevated CO 2 and O 3 could alter microbial community function and composition. Previously, we have observed that elevated CO 2 increased the microbial metabolism of cellulose and chitin, whereas elevated O 3 dampened this response. We hypothesized that this change in metabolism under CO 2 and O 3 enrichment would be accompanied by a concomitant change in fungal community composition. We tested our hypothesis at the free-air CO 2 and O 3 enrichment (FACE) experiment at Rhinelander, Wisconsin, in which Populus tremuloides, Betula papyrifera, and Acer saccharum were grown under factorial CO 2 and O 3 treatments. We employed extracellular enzyme analysis to assay microbial metabolism, phospholipid fatty acid (PLFA) analysis to determine changes in microbial community composition, and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) to analyze the fungal community composition. The activities of 1,4-b-glucosidase (+37%) and 1,4,-b-N-acetylglucosaminidase (+84%) were significantly increased under elevated CO 2 , whereas 1,4-b-glucosidase activity (À25%) was significantly suppressed by elevated O 3. There was no significant main effect of elevated CO 2 or O 3 on fungal relative abundance, as measured by PLFA. We identified 39 fungal taxonomic units from soil using DGGE, and found that O 3 enrichment significantly altered fungal community composition. We conclude that fungal metabolism is altered under elevated CO 2 and O 3 , and that there was a concomitant change in fungal community composition under elevated O 3. Thus, changes in plant inputs to soil under elevated CO 2 and O 3 can propagate through the microbial food web to alter the cycling of C in soil. Keywords Free-air CO 2 and O 3 enrichment AE Extracellular enzymes AE Polymerase chain reactiondenaturing gradient gel electrophoresis AE Soil microbial community AE Fungal metabolism Communicated by Ram Oren

Boswellia sacra, an economically important frankincense-producing tree found in the desert woodlands of Oman, is least known for its endophytic fungal diversity and the potential of these fungi to produce extracellular enzymes and auxins. We isolated various fungal endophytes belonging to Eurotiales (11.8%), Chaetomiaceae (17.6%), Incertae sadis (29.5%), Aureobasidiaceae (17.6%), Nectriaceae (5.9%) and Sporomiaceae (17.6%) from the phylloplane (leaf) and caulosphere (stem) of the tree. Endophytes were identified using genomic DNA extraction, PCR amplification and sequencing the internal transcribed spacer regions, whereas a detailed phylogenetic analysis of the same gene fragment was made with homologous sequences. The endophytic colonization rate was significantly higher in the leaf (5.33%) than the stem (0.262%). The Shannon-Weiner diversity index was H 0 0.8729, while Simpson index was higher in the leaf (0.583) than in the stem (0.416). Regarding the endophytic fungi's potential for extracellular enzyme production, fluorogenic 4-methylumbelliferone standards and substrates were used to determine the presence of cellulases, phosphatases and glucosidases in the pure culture. Among fungal strains, Penicillum citrinum BSL17 showed significantly higher amounts of glucosidases (62.15±1.8 μM -1 min -1 mL) and cellulases (62.11±1.6 μM -1 min -1 mL), whereas Preussia sp. BSL10 showed significantly higher secretion of glucosidases (69.4±0.79 μM -1 min -1 mL) and phosphatases (3.46 ±0.31μM -1 min -1 mL) compared to other strains. Aureobasidium sp. BSS6 and Preussia sp.

Boswellia sacra, an economically important frankincense-producing tree found in the desert woodlands of Oman, is least known for its endophytic fungal diversity and the potential of these fungi to produce extracellular enzymes and auxins. We isolated various fungal endophytes belonging to Eurotiales (11.8%), Chaetomiaceae (17.6%), Incertae sadis (29.5%), Aureobasidiaceae (17.6%), Nectriaceae (5.9%) and Sporomiaceae (17.6%) from the phylloplane (leaf) and caulosphere (stem) of the tree. Endophytes were identified using genomic DNA extraction, PCR amplification and sequencing the internal transcribed spacer regions, whereas a detailed phylogenetic analysis of the same gene fragment was made with homologous sequences. The endophytic colonization rate was significantly higher in the leaf (5.33%) than the stem (0.262%). The Shannon-Weiner diversity index was H 0 0.8729, while Simpson index was higher in the leaf (0.583) than in the stem (0.416). Regarding the endophytic fungi's potential for extracellular enzyme production, fluorogenic 4-methylumbelliferone standards and substrates were used to determine the presence of cellulases, phosphatases and glucosidases in the pure culture. Among fungal strains, Penicillum citrinum BSL17 showed significantly higher amounts of glucosidases (62.15±1.8 μM -1 min -1 mL) and cellulases (62.11±1.6 μM -1 min -1 mL), whereas Preussia sp. BSL10 showed significantly higher secretion of glucosidases (69.4±0.79 μM -1 min -1 mL) and phosphatases (3.46 ±0.31μM -1 min -1 mL) compared to other strains. Aureobasidium sp. BSS6 and Preussia sp.

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Chemical changes in leaf input to forest soils have been reported to affect decay processes. In this work, litter mass loss and decomposition constants (k) during 200 days in solid-state fermentation of the native tree Celtis tala Gill. ex Planch. and the exotic one Ligustrum lucidum Ait. with three common litter saprotrophic basidiomycetes were compared. Alterations in litter quality were characterized by solid-state13C NMR spectroscopy, pH, soluble sugars, ammonium, proteins, and phenol content determination and were associated with extracellular lignocellulolytic enzyme production. Differences in substrate decomposition related to litter type were observed for Leratiomyces ceres, achieving a higher k in the exotic L. lucidum litter, which might be attributed to the induction of manganese peroxidase activity. Substrate preference for alkyl C and more degradation of lignified compounds were found in such substrates. Although no statistical differences in mass loss were observed for...

Land use intensification often results in modification in plant cover and nutrient inputs with subsequent potential effects on composition and structure of soil microbial community and fractions. The objective of this study was to understand the long-term (N 22 yr) impacts of land use intensification (introduction of productive vegetation type, greater N fertilizer input and stocking rate) on soil microbial community composition and activity in Florida grazing lands. Experimental sites consisted of a gradient of management intensities ranging from native rangeland (lowest), silvopasture (intermediate), to sown pasture (highest). Increasing management intensity from native rangeland to sown promoted microbial biomass and activity. At the 0-10 cm, soil microbial biomass carbon (MBC) concentration was greater in sown pasture (334 mg kg −1) compared to silvopasture and native rangeland (193 and 232 mg kg −1 , respectively). Similarly, potentially mineralizable C (PMC) increased in response to grazing land intensification (1.2 mg CO 2-C kg −1 d −1 for sown pastures vs. 0.5 and 0.6 mg CO 2-C kg −1 d −1 for native rangeland and silvopasture, respectively). Sown pastures exhibited the greatest levels of β-glucosidase activity (203 nmol g −1 soil h. −1) and phospholipid fatty acid (PLFA) biomass (222 μmol kg −1 soil) compared to native rangeland and silvopasture. Results also demonstrated greater relative abundance of bacteria and less fungi as land use intensification increased from native rangeland to silvopasture or sown pasture. Our study indicated that long-term land use intensification affected the size, activity, and composition of soil microbial community in subtropical grazing lands.

Conidia of entomopathogenic fungi can penetrate the insect exoskeleton both by mechanic action of the germinative tube and by production of multiple proteases, chitinases, and lipases in response to the composition of the insect cuticle. Therefore the purpose of this work was to produce, to purify, and to characterize the structure of the proteases produced by the fungus Beauveria bassiana CG432, previously activated in adults of coffee berry borer (Hypothenemus hampei) grown under submerged culture conditions. A suspension containing 10 6 activated conidia/mL was inoculated to a culture medium at 28ºC and 150 rpm for 3 days. Protease extracts, were obtained by centrifugation at 8000g for 20 minutes, were fractionated and were concentrated by ultrafiltration using controlled porosity membranes of 100 kDa and 3 kDa, respectively. Gel filtration chromatography on Sephadex G-100 isolated one protein peak (peak II), which contained 56% of residues of the aminoacid aspartic acid, characterized by HPLC using an ODS-C18 reverse phase column. The peak protein showed specific activity 43 times superior when compared to the free-cell extract in bovine serum albumin, subtilisin-like protease activity, and a single protein band reveled by Brilliant Coomassie Blue on a gelatin zimogram PAGE electrophoresis, by native conditions. The homogeneity of peak II was confirmed by revelation of a single band during determination of the isoelectric pH 4.5, but molecular mass determination by PAGE-2D electrophoresis showed 2 bands of 23 and 26 kDa. Proteases were characterized as serine proteases with cysteine residues important to activity, since they had been inhibited by phenylmethylsulphonyl fluoride and p-chlormercuricbenzoic acid. Peak II proteases showed Km of 4x10-4 on subtilisin-like substrate.

Vegetable grafting is increasingly recognized as an effective and sustainable plant production alternative. Grafted plants usually show increased uptake of water and minerals compared with self-rooted plants, mostly thought a consequence of the vigorous rootstocks selected. However, while studies frequently addressed the effects of rootstocks on the performance of scions, knowledge on the influences of scions on biomass allocation, morphology, and metabolic activity of roots is rare. In particular, the plasticity of root traits affecting resource acquisition and its efficiency remains poorly understood. Two different rootstock species, Cucurbita maxima × Cucurbita moschata and Lagenaria siceraria, were grafted in combination with melon (Cucumis melo) and watermelon (Citrullus lanatus). Self-grafted rootstocks were used as control. Plant biomass and root traits were determined after destructive harvesting 30 and/or 60 days after grafting. Traits included biomass allocation, leaf and ...

Contents Summary 68 I. Introduction 68 II. Have ECM fungi retained genes with lignocellulolytic potential from saprotrophic ancestors? 69 III. Are genes with saprotrophic function expressed by ECM fungi when in symbiosis? 71 IV. Do transcribed enzymes operate to obtain N from SOM? 71 V. Is the organic N derived from SOM transferred to the plant host? 71 VI. Concluding remarks 72 Acknowledgements 72 References 72 SummaryThe view that ectomycorrhizal (ECM) fungi commonly participate in the enzymatic liberation of nitrogen (N) from soil organic matter (SOM) has recently been invoked as a key mechanism governing the biogeochemical cycles of forest ecosystems. Here, we provide evidence that not all evolutionary lineages of ECM have retained the genetic potential to produce extracellular enzymes that degrade SOM, calling into question the ubiquity of the proposed mechanism. Further, we discuss several untested conditions that must be empirically validated before it is certain that any lin...

In this review, we present a conceptual model which links plant communities and saprotrophic microbial communities through the reciprocal exchange of growth-limiting resources. We discuss the numerous ways human-induced environmental change has directly and indirectly impacted this relationship, and review microbial responses that have occurred to date. We argue that compositional shifts in saprotrophic microbial communities underlie functional responses to environmental change that have ecosystem-level implications. Drawing on a long-term, large-scale, field experiment, we illustrate how and why chronic atmospheric N deposition can alter saprotrophic communities in the soil of a widespread sugar maple (Acer saccharum) ecosystem in northeastern North America, resulting in the slowing of plant litter decay, the rapid accumulation of soil organic matter, and the accelerated production and loss of dissolved organic carbon (DOC). Compositional shifts in soil microbial communities, mediated by ecological interactions among soil saprotrophs, appear to lie at the biogeochemical heart of ecosystem response to environmental change.

The genus Chaetomium is a frequently occurring fungal taxon world-wide. Chaetomium and Chaetomium-like species occur in indoor environments, where they can degrade cellulose-based building materials, thereby causing structural damage. Furthermore, several species of this genus may also cause adverse effects on human health. The aims of this research were to identify Chaetomium and Chaetomium-like strains isolated from indoor environments in Hungary and Finland, two geographically distant regions of Europe with drier and wetter continental climates, respectively, and to study their morphological and physiological properties, as well as their extracellular enzyme activities, thereby comparing the Chaetomium and Chaetomium-like species isolated from these two different regions of Europe and their properties. Chaetomium and Chaetomium-like strains were isolated from flats and offices in Hungary, as well as from schools, flats, and offices in Finland. Fragments of the translation elongat...

The genus Chaetomium is a frequently occurring fungal taxon world-wide. Chaetomium and Chaetomium-like species occur in indoor environments, where they can degrade cellulose-based building materials, thereby causing structural damage. Furthermore, several species of this genus may also cause adverse effects on human health. The aims of this research were to identify Chaetomium and Chaetomium-like strains isolated from indoor environments in Hungary and Finland, two geographically distant regions of Europe with drier and wetter continental climates, respectively, and to study their morphological and physiological properties, as well as their extracellular enzyme activities, thereby comparing the Chaetomium and Chaetomium-like species isolated from these two different regions of Europe and their properties. Chaetomium and Chaetomium-like strains were isolated from flats and offices in Hungary, as well as from schools, flats, and offices in Finland. Fragments of the translation elongat...

Extracellular phosphohydrolases mediate the dephosphorylation of phosphoesters and influence bioavailability and loss of agricultural P to the environment to pose risks of impairment of sensitive aquatic ecosystems. Induction and culture of five strains of Aspergillus were conducted to develop a source of high-affinity and robust phosphohydrolases for detecting environmental P and quantifying bioactive P pools in heterogeneous environmental specimens. Enzyme stability and activity against organic P in poultry litter were evaluated in 71 samples collected across poultry producing regions of Arkansas, Maryland, and Oklahoma of the US Differences existed in strains' adaptability to fermentation medium as they showed a wide range of phytate-degrading activity. Phosphohydrolases from Aspergillus ficuum had highest activity when the strain was cultured on a primarily chemical medium, compared to Aspergillus oryzae which preferred a wheat bran-based organic medium. Kinetics parameters of A. ficuum enzymes (K m = 210 lM; V max of 407 nmol s À1) indicated phytic acid-degrading potential equivalent to that of commercial preparations. Purified A. ficuum phosphohydrolases effectively quantified litter bioactive P pools, showing that organic P occurred at an average of 54 (±14)% of total P, compared to inorganic phosphates, which averaged 41 (±12)%. Litter management and land application options must consider the high water-extractable and organic P concentrations and the biological availability of the organic enzymelabile P pool. Robustness of A. ficuum enzymes and simplicity of the in situ ligand-based enzyme assay may thus increase routine assessment of litter bioactive P composition to sense for on-farm accumulation of such environmentally-sensitive P forms.

Soil extracellular enzymes are pivotal for microbial nutrient cycling in the ecosystem. In order to study the effects of different nitrogen application rates under plastic film mulching on soil extracellular enzyme activities and stoichiometry, five nitrogen application levels (i.e., 0, 90, 150, 225 and 300 kg·hm−2) were set based on two treatments: plastic film mulching (PM) and no film mulching (LD). We measured the soil extracellular enzyme activities (EEAs) and stoichiometry (EES) of four enzymes (i.e., β-1,4-glucosidase (βG), leucine aminopeptidase (LAP), β-1,4-N-acetylaminoglucosidase (NAG) and alkaline phosphatase (AP)) involved in the C, N and P cycles of soil microorganisms in surface soil at five maize growth stages (seedling stage, jointing stage, trumpet stage, grout stage and harvest stage). The results showed that there were significant differences in soil EEA at different maize growth stages. The soil nutrient content and soil EEA were significantly improved under PM,...

Bitkiler, bitki ekstreleri ve dogal bilesikler yeni ilaclarin onemli kaynagidir. Vincetoxicum turleri Avrupa ve Cin halk tibbinda bir cok hastaligin tedavisinde geleneksel olarak kullanilmaktadir. V. canescens subsp. canescens Turkiye'nin dogusunda geleneksel tipda fungal enfeksiyonlarin tedavisinde kullanilmaktadir. Cesitli Vincetoxicum turleri (ornegin V.rossicum, V.stocksii, V.nigrum, V.hirundinaria) icin antibakteriyal, antifungal, antidiyareik, antispazmodik, antileishmaniyal, antimalaryal, sitotoksik, antifeedant ve buyume inhibisyonu gibi bir cok biyolojik aktivite bilimsel calismalarda gosterilmektedir. Bu calismada bes Vincetoxicum taksonu (V. canescens subsp. canescens, V. canescens subsp. pedunculata, V. fuscatum subsp. fuscatum, V. fuscatum subsp. boissieri and V. parviflorum) Turkiye'nin farkli bolgelerinde, dogal habitatlarindan toplanmis ve kok ve toprak ustu kisimlaridan farkli polaritede otuz ekstre (diklorometan, metanol:diklorometan (1:1), metanol) ve on t...

Plants, plant extracts and natural compounds are important source of new drugs. Vincetoxicum species are traditionally used for the treatment of many disease in European and Chinese folk medicine. V. canescens subsp. canescens has been used for  treatment of fungal infections in traditional medicine in east part of Turkey. Many biological activities including antibacterial, antifungal, antidiarrheal, antispasmodic, antileishmanial, antimalarial, cytotoxic, antifeedant and growth inhibition have been shown for several Vincetoxicum species (e.g V.rossicum , V.stocksii , V.nigrum, V.hirundinaria ) in scientific reports. In this study five Vincetoxicum taxa ( V. canescens subsp. canescens , V. canescens subsp . pedunculata, V. fuscatum subsp. fuscatum, V. fuscatum subsp. boissieri and V. parviflorum ) were collected from their natural habitats in different parts of Turkey and thirty different polarity extracts (dichloromethane, methanol:dichloromethane (1:1), methanol) and ten total eth...

Objective: The study aimed to investigate the interactions between twelve extracellular enzymes and nuclear factor erythroid 2-related factor 2 (Nrf2) in the active site. Methods: The Zdock web server was accessed to perform molecular docking simulations for predicting interactions between the extracellular enzymes and the active site of Nrf2. The Z score analysis revealed enzymes with high scores, indicating strong and statistically significant interactions with Nrf2. Results: DNase 1, α-amylase, and lecithinase C exhibited notably high Z scores, suggesting potential key players in modulating Nrf2-mediated signaling pathways. The examination of salt bridges showed enzymes with more ionic interactions, suggesting enhanced stability and potential for strong binding within the active site of Nrf2. This characteristic might be crucial for enzymatic inhibition of Nrf2's activity. Conclusion: In conclusion, the findings highlight enzymes, including DNase 1, α-amylase, and lecithinase C, as promising candidates for further exploration as potential inhibitors of NRF2-mediated cellular responses.

There is a growing body of knowledge that ecosystem functions, in particular soil-based ecosystem functions, are related to biodiversity. However, how plant species diversity influences soil-based functions along post-agricultural secondary succession is still a largely ignored question in Mediterranean semi-arid conditions. Therefore, we used the plant functional group approach to investigate the relationships between plant species diversity indices and soil-based functions including microbial biomass carbon (MBC), basal respiration (BR) and carbon sequestration (CS) across three different stages of the vegetation succession corresponding to ~ five years after agricultural abandonment, ~ 15 years after abandonment, and oak forests which represent the terminal stage. We also tested if these relationships are supported by the niche complementarity and selection effect hypotheses. The results showed that soil-based functions significantly increased with time since abandonment as BR, MBC and CS increased respectively by 1.7, 1.5 and 2.7 times across the three successional stages. We also found strong correlations between the diversity indices and the soil-based functions BR, MBC and CS which were positive for richness (R 2 values: 0.75, 0.74 and 0.75) and Shannon diversity (R 2 values: 0.61, 0.58 and 0.61) but negative for evenness (R 2 values: 0.38, 0.38 and 0.36 for, respectively). Similarly, richness and Shannon diversity of the different plant functional groups positively correlated with soil-based functions. However, contrasted results were found for evenness which positively correlated with soil-based functions for perennial grass only. We suggested that increasing the diversity of plant species and facilitating dominant species would be needed to improve the soil-based ecosystem functions after abandonment of degraded soils. This study also revealed that the mechanisms behind the relationships between biodiversity and ecosystems functions were influenced by the vegetative forms. Keywords Carbon sequestration. Cropland abandonment. Land use change. Richness. Semiarid forest Highlights  Species diversity and soil-based functions improve along the successional stages after land abandonment  The relationships between plant diversity and soil-based functions are influenced by the plant functional groups..  Niche complementarity plays a more vital role in soil-based ecosystem functions than the selection effect.

The Patagonian Andes possess a great variety of glaciers, large temperate ice masses, and glacially formed water bodies. Most of these environments are included in protected areas characterized by low anthropogenic impact and minimal atmospheric pollution. Studies on occurrence of psychrotolerant (cold-adapted) and psychrophilic yeasts in these natural environments have allowed the characterization of native cold-adapted yeast communities, the description of six novel species, as well as description of the capability of these yeasts to produce extracellular enzymes, and other metabolites (carotenoids and mycosporines). Cold-adapted yeasts from Patagonian glaciers were able to hydrolyze natural polymers (casein, lipids, starch, pectin and carboxymethylcellulose) at low temperatures and some were able to produce photo-protective compounds. These results suggest a significant ecological role of these organisms as organic matter decomposers and nutrient cyclers, also reveal that some of...

Chemical changes in leaf input to forest soils have been reported to affect decay processes. In this work, litter mass loss and decomposition constants (k) during 200 days in solid-state fermentation of the native tree Celtis tala Gill. ex Planch. and the exotic one Ligustrum lucidum Ait. with three common litter saprotrophic basidiomycetes were compared. Alterations in litter quality were characterized by solid-state13C NMR spectroscopy, pH, soluble sugars, ammonium, proteins, and phenol content determination and were associated with extracellular lignocellulolytic enzyme production. Differences in substrate decomposition related to litter type were observed for Leratiomyces ceres, achieving a higher k in the exotic L. lucidum litter, which might be attributed to the induction of manganese peroxidase activity. Substrate preference for alkyl C and more degradation of lignified compounds were found in such substrates. Although no statistical differences in mass loss were observed for...

In the recent times, there has been a reversed interest in the search of plant growth promoting endophytes (PGPE) for sustainable crop production. Mango is an economically important fruit crop, which is highly sensitive to saline environment. In the present study the importance of PGPR in growth promotion and their ability to elicit 'induced systemic tolerance' against abiotic (sodicity) stresses has been documented. Sixteen (16) putative of endophytic bacteria were isolated from sodicity tolerant polyembryonic mango root stock of GPL-3 and ML-4 from Shivari experimental farm, Central Soil

Predicted changes in the intensity and frequency of climate extremes urge a better mechanistic understanding of the stress response of microbially mediated carbon (C) and nutrient cycling processes. We analyzed the resistance and resilience of microbial C, nitrogen (N), and phosphorus (P) cycling processes and microbial community composition in decomposing plant litter to transient, but severe, temperature disturbances, namely, freeze-thaw and heat. Disturbances led temporarily to a more rapid cycling of C and N but caused a down-regulation of P cycling. In contrast to the fast recovery of the initially stimulated C and N processes, we found a slow recovery of P mineralization rates, which was not accompanied by significant changes in community composition. The functional and structural responses to the two distinct temperature disturbances were markedly similar, suggesting that direct negative physical effects and costs associated with the stress response were comparable. Moreover,...

L-glutaminase (L-glutamine amidohydrolase, EC 3.5.1.2) is a very important enzyme due to its role as flavor enhancer and antileukemic agent. Salt-tolerant L-glutaminase produced bymarine bacteria is favorable in food industries. This study describes the screening of L- glutaminase producing marine bacteria from Sangihe-Talaud Sea, North Sulawesi, Indonesia.Screening of L-glutaminase was performed using a liquid medium and identification of selected isolate was  performed using molecular-based 16S rDNA. Results showed that there were 7 isolates produced positive results of L-glutaminase, and one of them (II.1 isolate) produced the highest activity, i.e 147.99 U/L, equivalent to the specific activity of 62.32 U/mg. The isolate then selected for further study. Bacterial identification based on 16S rRNA sequencing has revealed that the isolate was 96% similar to Pseudomonas aeruginosa strain CG-T8. Characterization of extracellular L-glutaminase from the II.1 isolate showed that the enz...

In the recent times, there has been a reversed interest in the search of plant growth promoting endophytes (PGPE) for sustainable crop production. Mango is an economically important fruit crop, which is highly sensitive to saline environment. In the present study the importance of PGPR in growth promotion and their ability to elicit 'induced systemic tolerance' against abiotic (sodicity) stresses has been documented. Sixteen (16) putative of endophytic bacteria were isolated from sodicity tolerant polyembryonic mango root stock of GPL-3 and ML-4 from Shivari experimental farm, Central Soil

Sewage treatment plants are sources of inorganic and organic matter as well as contaminants for the receiving watercourses. We analyzed the ecological consequences of such effluents by following a holistic and synecological ecotoxicological approach based on quantifying extracellular enzyme activities (EEA), primary production and bacterial cell, and biomass production rates. Samples were obtained at three locations at the Rivers Holtemme and Elbe, Germany and Lower Jordan River, Israel and West Bank, as well as from their adjacent sewage treatment plants. Blending river samples with sewage treatment plant effluents mainly resulted in a stimulation of EEAs, which was diminished in blends with 0.2-μm filtered sewage treatment plant effluents. Stimulation for primary production and bacterial cell and biomass production of River Holtemme and Elbe samples was observed, and inhibition of these rates for Lower Jordan River samples probably linked to generally high turbidity. The quantified bacterial biomass versus cell production rates showed almost unbalanced (≫ 1) growth. Very high biomass to cell production ratios were found for sewage and sewage-containing samples, which provides a semi-quantitative indicator function for high quantities of microbial easy utilizable dissolved organic matter as nutrition source. The presented approach enables the simultaneous quantification of inhibitory and stimulating toxic responses as well as supplying ecosystem-based data for policy decision-making, and for direct incorporation in models to derive management and remediation strategies.

The present study was carried out to screen autochthonous gut bacteria in freshwater air breathing walking catfish, Clarias batrachus Linnaeus. Altogether, 100 extracellular enzyme-producing bacteria were isolated from the foregut (FG) and hindgut (HG) regions. Data were presented as log viable counts g-1 gut (LVC). The occurrence of heterotrophic bacterial population was higher in the FG region (LVC = 8.25) than the HG (LVC= 7.3). Similarly, proteolytic, amylolytic and lipolytic bacteria in FG outnumbered (LVC=7.25, 6.77 and 5.23 respectively) the HG (LVC=6.38, 5.58 and 4.04 respectively). However, occurrence of cellulolytic bacteria in both, FG and HG was less (LVC=2.1 and 1.34 respectively) in comparison to the other extracellular enzymeproducing bacteria. Out of the 100 bacterial isolates, 22 isolates were primarily selected through qualitative assay of extracellular enzyme activities. Among them, 3 promising isolates were chosen as potent extracellular enzyme producers on the basis of cumulative scores (≥11) of the qualitative assay and quantitative enzyme assay. Maximum protease activity was revealed by the strain FG10 (201±2.40U), while FG43 exhibited maximum amylase (208.3±10.8U) and lipase (4.73±0.05U) activities. Among the strains isolated from the HG, the highest protease (188.3±1.2U), amylase (97.6±0.46U) and lipase (3.7±0.11U) activities were recorded with the strain HG01. The isolates (FG10, FG43 and HG01) were studied through 16S rRNA partial gene sequence analyses and were identified as Bacillus aryabhattai (KP784311), B. flexus (KR809411), and B. cereus (KR809412), respectively. Further studies are to be conducted to evaluate the efficacy of these strains in vivo to improve the overall health status of the C. batrachus juveniles.

In the recent times, there has been a reversed interest in the search of plant growth promoting endophytes (PGPE) for sustainable crop production. Mango is an economically important fruit crop, which is highly sensitive to saline environment. In the present study the importance of PGPR in growth promotion and their ability to elicit 'induced systemic tolerance' against abiotic (sodicity) stresses has been documented. Sixteen (16) putative of endophytic bacteria were isolated from sodicity tolerant polyembryonic mango root stock of GPL-3 and ML-4 from Shivari experimental farm, Central Soil

ABSTRACTA cold-tolerant fungal strainThelebolus microsporuswas investigated for the first time for its pigment and fatty acid production. High-performance liquid chromatography analysis confirmed the presence of carotenoid pigment. Gas chromatography observations showed the presence of major fatty acids: myristic acid (14:0), palmitic acid (16:0), stearic acid (18:0), heptadecanoic acid (17:0), linolenic acid (18:3) and linoleic acid (18:2). Of these, linolenic acid, a polyunsaturated fatty acid, was present in substantial quantity, suggesting that it may have a role in adapting the fungus to low Antarctic temperatures by modulating membrane fluidity. The commercial application of linolenic acid is as a food supplement for humans suffering from eczema, cardiovascular disease and diabetic neuropathy. Another fatty acid, linoleic acid, a precursor of 1-octen-3-ol, is the principal aromatic compound in most fungi and has also been documented in this strain. Screening of the fungal cult...

In the recent times, there has been a reversed interest in the search of plant growth promoting endophytes (PGPE) for sustainable crop production. Mango is an economically important fruit crop, which is highly sensitive to saline environment. In the present study the importance of PGPR in growth promotion and their ability to elicit 'induced systemic tolerance' against abiotic (sodicity) stresses has been documented. Sixteen (16) putative of endophytic bacteria were isolated from sodicity tolerant polyembryonic mango root stock of GPL-3 and ML-4 from Shivari experimental farm, Central Soil

While past research has studied forest succession on decadal timescales, ecosystem responses to rapid shifts in nutrient dynamics within the first months to years of succession after fire (e.g., carbon (C) burn-off, a pulse in inorganic nitrogen (N), accumulation of organic matter, etc.) have been less well documented. This work reveals how rapid shifts in nutrient availability associated with fire disturbance may drive changes in soil enzyme activity on short timescales in forest secondary succession. In this study, we evaluate soil chemistry and decomposition extracellular enzyme activity (EEA) across time to determine whether rapid shifts in nutrient availability (1-29 months after fire) might control microbial enzyme activity. We found that, with advancing succession, soil nutrients correlate with C-targeting β-1,4-glucosidase (BG) EEA four months after the fire, and with N-targeting β-1,4-N-acetylglucosaminidase (NAG) EEA at 29 months after the fire, indicating shifting nutrient limitation and decomposition dynamics. We also observed increases in BG:NAG ratios over 29 months in these recently burned soils, suggesting relative increases in microbial activity around C-cycling and C-acquisition. These successional dynamics were unique from seasonal changes we observed in unburned, forested reference soils. Our work demonstrates how EEA may shift even within the first months to years of ecosystem succession alongside common patterns of post-fire nutrient availability. Thus, this work emphasizes that nutrient dynamics in the earliest stages of forest secondary succession are important for understanding rates of C and N cycling and ecosystem development.

While diversity studies and screening for enzyme activities are important elements of understanding fungal roles in the soil ecosystem, extracting and purifying the target enzyme from the fungal cellular system is also required to characterize the enzyme. This is, in particular, necessary before developing the enzyme for industrial-scale production. In the present study, partially purified α-amylase was obtained from strains of Pseudogymnoascus sp. obtained from Antarctic and Arctic locations. Partially purified α-amylases from these polar fungi exhibited very similar characteristics, including being active at 15 °C, although having a small difference in optimum pH. Both fungal taxa are good candidates for the potential application of cold-active enzymes in biotechnological industries, and further purification and characterization steps are now required. The α-amylases from polar fungi are attractive in terms of industrial development because they are active at lower temperatures an...

Soil organic matter is a biological system that functions as an integrated whole. These assemblies have different properties, functions, and decomposition times. SOM is one of the main determinants of soil productivity. Our studies were carried out in a temperate deciduous oak forest on Luvisols soil. In the DIRT Project (Detritus Input and Removal Treatments), the following treatments were applied: Double Litter, Double Wood, Control, No Litter, No Root and No Input. Our objective was to compare the effect of withdrawal or doubling of organic matter on the protein pattern of the soil and the biological activity and changes in labile C (permanganate-oxidizable carbon) content in a long-term organic matter manipulation experiment. Patterns of thermostable proteins, soil dehydrogenase enzyme activity, CO2 emission, and POXC content were measured at the most biologically active soil depth of 0–5 cm after 23 years of treatment. Our results show that the enzyme activities of the litter r...

Vast montado areas are threatened by degradation, as the result of a long history of land use changes. Since improved pastures have been installed aiming soil quality improvement and system sustainability, it is crucial to evaluate the effects of these management changes on soil organic matter status and soil biological activity, as soil quality indicators. Therefore, a 35-yr old improved pasture and a natural pasture were studied, considering areas beneath tree canopy and in the open. Total organic C, total N, hot water soluble (HWS) and particulate (POM) C, microbial biomass C (MBC) and N (MBN), C mineralization rate (CMR) and net N mineralization rate (NMR) were determined. In addition, for a 1-yr period, soil β-glucosidase, urease, proteases and acid phosphomonoesterase were periodically determined. Improved pasture promoted the increase of soil C and N through POM-C increment, particularly beneath the trees canopies. The two study pastures did not show differences regarding soil microbial biomass, but variations in CMR, HWS-C and N availability (proteases and urease activities) suggest divergent soil microbial communities. Tree regulator role on C, N and P transformation processes in soil was confirmed.

Description of the subject. Extracellular enzymes from filamentous fungi are increasingly used in eco-friendly biotransformation processes. Their relevant technological role and their stability towards extreme process conditions make of them the first sustainable solution for the elaboration of bio-based products from biomass conversion. Objectives. This paper describes the isolation of filamentous fungi from decaying plant material in the region of Meknes (northern central Morocco) and the assessment of their ability to breakdown lignocellulose. The objective is to select performant fungi with enzymatic machinery adapted to local environment and with potential for the breakdown of the regional specific lignocellulosic by-products into potentially high-value molecules. Method. Cereals, decaying wood, olive-pomace and -pulp and their composts were used to isolate lignocellulolytic fungi. One hundred twenty-seven pure strains were isolated and screened at 25 °C on selective media with...

A novel mesophilic strain, R5, was isolated from Osaka, Japan. The growth temperature of the strain ranged from 10 to 40°C with optimal growth at 30°C. Cells of strain R5 were highly motile small rods. The full-length 16S rRNA sequence was 99% homologous to that of Bacillus subtilis strain 168. The optimum pH and NaCl concentration for growth of the strain were 7.0 and 3%, respectively. Based on the biochemical characteristics and 16S rRNA sequences R5 was identified as a strain of B. subtilis. The strain R5 produced protease, cellulase, amylase, lipase/esterase, xylanase and a biosurfactant extracellularly. The gene encoding xylanase was cloned and expressed in Escherichia coli. The gene encoded a protein consisting of 213 amino acids with a relative molecular mass of 23 kDa. The gene product was purified and examined for enzymatic characteristics. The recombinant enzyme exhibited highest activity at temperatures ranging from 40 to 50°C and at pH 6.0. The enzyme activity was enhanced in the presence of metal cations. The V max and K m values of the recombinant enzyme towards xylan from beechwood were 5550 nkat/mg and 4.5 mg/mL, respectively.