The fate of an auxotrophic Escherichia coli K12 strain (NF1830) in coastal water was investigated... more The fate of an auxotrophic Escherichia coli K12 strain (NF1830) in coastal water was investigated. The E. coli K12 were enumerated after incubation for varying times in seawater. Incubated in raw seawater at 15 and 20°C, the NF1830 decreased from 10 6 cfu/ml to below detection within six days of incubation, but when incubated at 7°C it persisted longer. The NF1830 was capable of cell division in sterile seawater. Growth was also shown to occur in raw seawater in the presence of autoclaved sediment. The E. coli K12 decreased in number at a much lower rate when incubated in seawater treated with eukaryotic inhibitors. These findings suggest that the die-off of the auxotrophic E. coli K12 strain seen in the raw seawater was caused by grazing of bacterial predators in the seawater.
Applied and Environmental Microbiology, Mar 1, 2018
Extreme habitats are not only limited to natural environments, but also exist in manmade systems,... more Extreme habitats are not only limited to natural environments, but also exist in manmade systems, for instance, household appliances such as dishwashers. Limiting factors, such as high temperatures, high and low pHs, high NaCl concentrations, presence of detergents, and shear force from water during washing cycles, define microbial survival in this extreme system. Fungal and bacterial diversity in biofilms isolated from rubber seals of 24 different household dishwashers was investigated using next-generation sequencing. Bacterial genera such as Pseudomonas, Escherichia, and Acinetobacter, known to include opportunistic pathogens, were represented in most samples. The most frequently encountered fungal genera in these samples belonged to Candida, Cryptococcus, and Rhodotorula, also known to include opportunistic pathogenic representatives. This study showed how specific conditions of the dishwashers impact the abundance of microbial groups and investigated the interkingdom and intrakingdom interactions that shape these biofilms. The age, usage frequency, and hardness of incoming tap water of dishwashers had significant impact on bacterial and fungal community compositions. Representatives of Candida spp. were found at the highest prevalence (100%) in all dishwashers and are assumed to be one of the first colonizers in recently purchased dishwashers. Pairwise correlations in tested microbiomes showed that certain bacterial groups cooccur, as did the fungal groups. In mixed bacterial-fungal biofilms, early adhesion, contact, and interactions were vital in the process of biofilm formation, where mixed complexes of bacteria and fungi could provide a preliminary biogenic structure for the establishment of these biofilms.
bioRxiv (Cold Spring Harbor Laboratory), Nov 12, 2020
Integrated and quantitative observations of antibiotic resistance genes (ARGs) in urban water sys... more Integrated and quantitative observations of antibiotic resistance genes (ARGs) in urban water systems (UWSs) are lacking. We sampled three UWSs for clinically important extended spectrum β-lactamase (ESBL) and carbapenemase (CP) genes, mobile genetic elements and microbial communities. Sewage-especially from hospitals-carried substantial loads of ESBL and CP genes (10 6-10 7 per person equivalent), but those loads progressively declined along the UWS, resulting in minimal emissions (10 1-10 4 copies per person equivalent). Removal was primarily during sewage conveyance (65% ± 36%) rather than within sewage treatment (34% ± 23%). The ARGs clustered in groups based on their persistence; less persistent groups were associated to putative host taxa (especially Enterobacteriaceae and Moraxellaceae), while more persistent groups appear horizontally transferred as they correlated with mobile genetic elements. This first documentation of a substantial ARG reduction during sewage conveyance provides opportunities for antibiotic resistance management and a caution for sewage-based ARG surveillance. .
Users may download and print one copy of any publication from the public portal for the purpose... more Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
bioRxiv (Cold Spring Harbor Laboratory), Jan 2, 2018
DAtest is an R package for directly comparing different statistical methods for differential abun... more DAtest is an R package for directly comparing different statistical methods for differential abundance and expression analysis on a dataset of interest; be it data from RNA-seq, proteomics, metabolomics or a microbial marker-gene survey. A myriad of statistical methods exists for conducting these analyses, and with this tool we give the analyst an empirical foundation for choosing a method suitable for a specific dataset. The package supports categorical and quantitative variables, paired/block experimental designs, and the inclusion of covariates. It is freely available at GitHub: https://github.com/Russel88/DAtest along with detailed instructions. .
Take-down policy If you believe that this document breaches copyright please contact us providing... more Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
Motivation: Wastewater Treatment Plants (WWTPs) harbor a dense and diverse microbial community. T... more Motivation: Wastewater Treatment Plants (WWTPs) harbor a dense and diverse microbial community. They constantly receive antimicrobial residues and resistant strains, and therefore provide conditions for Horizontal Gene Transfer (HGT) of antimicrobial resistance determinants. This facilitates the transmission of clinically important genes between, e.g., enteric and environmental bacteria, and vice versa. Despite the clinical importance, tools for predicting HGT remain underdeveloped. Results: In this study, we examined to which extent water cycle microbial community composition, as inferred by partial 16S rRNA gene sequences, can predict plasmid permissiveness, i.e., the ability of cells to receive a plasmid through conjugation, based on data from standardized filter mating assays using fluorescent bio-reporter plasmids. We leveraged a range of machine learning models for predicting the permissiveness for each taxon in the community, representing the range of hosts a plasmid is able to transfer to, for three broad host-range resistance IncP plasmids (pKJK5, pB10, and RP4). Our results indicate that the predicted permissiveness from the best performing model (random forest) showed a moderate-to-strong average correlation of 0.49 for pB10 (95% CI: 0.44, 0.55), 0.43 for pKJK5 (0.95% CI: 0.41, 0.49) and 0.53 for RP4 (0.95% CI: 0.48, 0.57) with the experimental permissiveness in the unseen test dataset. Predictive phylogenetic signals occurred despite the broad host-range nature of these plasmids. Our results provide a framework that contributes to the assessment of the risk of antimicrobial resistance (AMR) pollution in wastewater systems.
The current epidemic of antibiotic resistance has been facilitated by the wide and rapid horizont... more The current epidemic of antibiotic resistance has been facilitated by the wide and rapid horizontal dissemination of antibiotic resistance genes (ARGs) in microbial communities. Indeed, ARGs are often located on plasmids, which can efficiently shuttle genes across diverse taxa. While the existence conditions of plasmids have been extensively studied in a few model bacterial populations, their fate in complex bacterial communities is poorly understood. Here, we coupled plasmid transfer assays with serial growth experiments to investigate the persistence of the broad-host-range IncP-1 plasmid pKJK5 in microbial communities derived from a sewage treatment plant. The cultivation conditions combined different nutrient and oxygen levels, and were non-selective and non-conducive for liquid-phase conjugal transfer. Following initial transfer, the plasmid persisted in almost all conditions during a 10-day serial growth experiment (equivalent to 60 generations), with a transient transconjugant incidence up to 30%. By combining cell enumeration and sorting with amplicon sequencing, we mapped plasmid fitness effects across taxa of the microbial community. Unexpected plasmid fitness benefits were observed in multiple phylotypes of Aeromonas, Enterobacteriaceae, and Pseudomonas, which resulted in community-level plasmid persistence. We demonstrate, for the first time, that plasmid fitness effects across community members can be estimated in highthroughput without prior isolation. By gaining a fitness benefit when carrying plasmids, members within complex microbial communities might have a hitherto unrecognised potential to maintain plasmids for long-term community-wide access.
Users may download and print one copy of any publication from the public portal for the purpose... more Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
Frontiers in Cellular and Infection Microbiology, Mar 29, 2022
The toolbox available for microbiologists to study interspecies interactions is rapidly growing, ... more The toolbox available for microbiologists to study interspecies interactions is rapidly growing, and with continuously more advanced instruments, we are able to expand our knowledge on establishment and function of microbial communities. However, unravelling molecular interspecies interactions in complex biological systems remains a challenge, and interactions are therefore often studied in simplified communities. Here we perform an in-depth characterization of an observed interspecies interaction between two co-isolated bacteria, Xanthomonas retroflexus and Paenibacillus amylolyticus. Using microsensor measurements for mapping the chemical environment, we show how X. retroflexus promoted an alkalization of its local environment through degradation of amino acids and release of ammonia. When the two species were grown in proximity, the modified local environment induced a morphological change and growth of P. amylolyticus followed by sporulation. 2D spatial metabolomics enabled visualization and mapping of the degradation of oligopeptide structures by X. retroflexus and morphological changes of P. amylolyticus through e.g. the release of membrane-associated metabolites. Proteome analysis and microscopy were used to validate the shift from vegetative growth towards sporulation. In summary, we demonstrate how environmental profiling by combined
Users may download and print one copy of any publication from the public portal for the purpose... more Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
Wastewater Treatment Plants (WWTPs) contain a diverse microbial community with high cell density.... more Wastewater Treatment Plants (WWTPs) contain a diverse microbial community with high cell density. They constantly receive antimicrobial residues and resistant strains and, therefore, may offer conditions for the Horizontal Gene Transfer (HGT) of antimicrobial resistance determinants, transmitting clinically important genes between, e.g., enteric and environmental bacteria and vice versa. Despite the clinical importance, tools for predicting HGT are still under-developed. In this study, we examined to which extent microbial community composition, as inferred by partial 16S rRNA gene sequences, can predict plasmid permissiveness, i.e., the ability of cells to receive a plasmid through conjugation, for microbial communities in the water cycle, using data from standardized filter mating assays using fluorescent bio-reporter plasmids. We leveraged a range of machine learning models for predicting the permissiveness for each taxon in the community, translating to the range of hosts a plas...
Background: A One Health approach requires integrative research to elucidate antimicrobial resist... more Background: A One Health approach requires integrative research to elucidate antimicrobial resistance (AMR) in the environment and the risks it poses to human health. Research on this topic involves experts from diverse backgrounds and professions. Shortcomings exist in terms of consistent, complete, and transparent reporting in many environmental studies. Standardized reporting will improve the quality of scientific papers, enable metaanalyses and enhance the communication among different experts. In this study, we aimed to generate a consensus of reporting standards for AMR research in wastewater and related aquatic environments. Methods: Based on a risk of bias assessment of the literature in a systematic review, we proposed a set of study quality indicators. We then used a multistep modified Delphi consensus to develop the EMBRACE-WATERS statement (rEporting antiMicroBial ResistAnCE in WATERS), a checklist of recommendations for reporting in studies of AMR in wastewater and related aquatic environments. Findings: Consensus was achieved among a multidisciplinary panel of twenty-one experts in three steps. The developed EMBRACE-WATERS statement incorporates 21 items. Each item contains essential elements of high-quality reporting and is followed by an explanation of their rationale and a reporting-example. The EMBRACE-WATERS statement is primarily intended to be used by investigators to ensure transparent and comprehensive reporting of their studies. It can also guide peer-reviewers and editors in evaluation of manuscripts on AMR in the aquatic environment. This statement is not intended to be used to guide investigators on the methodology of their research. Interpretation: We are hopeful that this statement will improve the reporting quality of future studies of AMR in wastewater and related aquatic environments. Its uptake would generate a common language to be used among researchers from different disciplines, thus advancing the One Health approach towards understanding AMR spread across aquatic environments. Similar initiatives are needed in other areas of One Health research.
ABSTRACTA soil column split-root experiment was designed to investigate the ability of apple repl... more ABSTRACTA soil column split-root experiment was designed to investigate the ability of apple replant disease (ARD)-causing agents to spread in soil. ‘M26’ apple rootstocks grew into a top layer of Control soil, followed by a barrier-free split-soil layer (Control soil/ARD soil). We observed a severely reduced root growth, concomitant with enhanced gene expression of phytoalexin biosynthetic genes and phytoalexin content in roots from ARD soil, indicating a pronounced local plant defense response. Amplicon sequencing (bacteria, archaea, fungi) revealed local shifts in diversity and composition of microorganisms in the rhizoplane of roots from ARD soil. An enrichment of operational taxonomic units affiliated to potential ARD fungal pathogens (Ilyonectria and Nectria sp.) and bacteria frequently associated with ARD (Streptomyces, Variovorax) was noted. In conclusion, our integrated study supports the idea of ARD being local and not spreading into surrounding soil, as only the roots in ...
For a century, the MetalEurop foundry released metals into the river "La Deûle". Previous work re... more For a century, the MetalEurop foundry released metals into the river "La Deûle". Previous work revealed higher microbial diversity in metal impacted sediments, and horizontal gene transfer mediated by conjugative plasmids was suggested to drive the community adaptation to metals. We used an integrative state-of-the-art molecular approach coupling quantitative PCR, conjugation assays, flow cytometry, fluorescence activated cell sorting and 16S rRNA gene amplicon sequencing to investigate the presence of conjugative plasmids and their propagation patterns in sediment microbiomes. We highlighted the existence of a native broad-host range IncP conjugative plasmid population in polluted sediments, confirming their ecological importance for microbial adaptation. However, despite incompatibilities and decreased transfer frequencies with our own alien IncP plasmid, we evidenced that a wide diversity of bacterial members was still prone to uptake the plasmid, indicating that sediment microbial communities are still inclined to receive conjugative plasmids from the same group. We observed that metal pollution favoured exogenous plasmid transfer to specific metal-selected bacteria, which are
The current epidemic of antibiotic resistance has been facilitated by the wide and rapid horizont... more The current epidemic of antibiotic resistance has been facilitated by the wide and rapid horizontal dissemination of antibiotic resistance genes (ARGs) in microbial communities. Indeed, ARGs are often located on plasmids, which can efficiently shuttle genes across diverse taxa. While the existence conditions of plasmids have been extensively studied in a few model bacterial populations, their fate in complex bacterial communities is poorly understood. Here, we coupled plasmid transfer assays with serial growth experiments to investigate the persistence of the broad-host-range IncP-1 plasmid pKJK5 in microbial communities derived from a sewage treatment plant. The cultivation conditions combined different nutrient and oxygen levels, and were non-selective and non-conducive for liquid-phase conjugal transfer. Following initial transfer, the plasmid persisted in almost all conditions during a 10-day serial growth experiment (equivalent to 60 generations), with a transient transconjugan...
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