scholarly journals A Novel Enrichment Culture Highlights Core Features of Microbial Networks Contributing to Autotrophic Fe(II) Oxidation Coupled to Nitrate Reduction

2021 ◽  
pp. 1-16
Author(s):  
Yu-Ming Huang ◽  
Daniel Straub ◽  
Andreas Kappler ◽  
Nicole Smith ◽  
Nia Blackwell ◽  
...  
Keyword(s):  
Relative Abundance ◽  
Nitrate Reduction ◽  
Carbon Fixation ◽  
Enrichment Culture ◽  
Amplicon Sequencing ◽  
Microbial Interactions ◽  
Rrna Gene ◽  
Metal Oxidation ◽  
Core Features

Fe(II) oxidation coupled to nitrate reduction (NRFO) has been described for many environments. Yet very few autotrophic microorganisms catalysing NRFO have been cultivated and their diversity, as well as their mechanisms for NRFO <i>in situ</i> remain unclear. A novel autotrophic NRFO enrichment culture, named culture BP, was obtained from freshwater sediment. After more than 20 transfers, culture BP oxidized 8.22 mM of Fe(II) and reduced 2.42 mM of nitrate within 6.5 days under autotrophic conditions. We applied metagenomic, metatranscriptomic, and metaproteomic analyses to culture BP to identify the microorganisms involved in autotrophic NRFO and to unravel their metabolism. Overall, twelve metagenome-assembled genomes (MAGs) were constructed, including a dominant <i>Gallionellaceae</i> sp. MAG (≥71% relative abundance). Genes and transcripts associated with potential Fe(II) oxidizers in culture BP, identified as a <i>Gallionellaceae</i> sp., <i>Noviherbaspirillum</i> sp., and <i>Thiobacillus</i> sp., were likely involved in metal oxidation (e.g., <i>cyc2</i>, <i>mtoA</i>), denitrification (e.g., <i>nirK</i>/<i>S</i>, <i>norBC</i>), carbon fixation (e.g., <i>rbcL</i>), and oxidative phosphorylation. The putative Fe(II)-oxidizing protein Cyc2 was detected for the <i>Gallionellaceae</i> sp. Overall, a complex network of microbial interactions among several Fe(II) oxidizers and denitrifiers was deciphered in culture BP that might resemble NRFO mechanisms <i>in situ</i>. Furthermore, 16S rRNA gene amplicon sequencing from environmental samples revealed 36 distinct <i>Gallionellaceae</i> taxa, including the key player of NRFO from culture BP (approx. 0.13% relative abundance <i>in situ</i>). Since several of these <i>in situ</i>-detected <i>Gallionellaceae</i> taxa were closely related to the key player in culture BP, this suggests that the diversity of organisms contributing to NRFO might be higher than currently known.

scholarly journals Meta-omics reveal Gallionellaceae and Rhodanobacter as interdependent key players for Fe(II) oxidation and nitrate reduction in the autotrophic enrichment culture KS

2021 ◽  
Author(s):  
Yu-Ming Huang ◽  
Daniel Straub ◽  
Nia Blackwell ◽  
Andreas Kappler ◽  
Sara Kleindienst
Keyword(s):  
Nitrate Reduction ◽  
Carbon Fixation ◽  
Enrichment Culture ◽  
Nitrate Removal ◽  
Freshwater Ecosystems ◽  
Microbial Interactions ◽  
Respiratory Chain Complexes ◽  
Chain Complexes ◽  
Key Players ◽  
Individual Strain

Nitrate reduction coupled to iron(II) oxidation (NRFO) has been recognized as an environmentally important microbial process in many freshwater ecosystems. However, well-characterized examples of autotrophic nitrate-reducing iron(II)-oxidizing bacteria are rare and their pathway of electron transfer as well as their interaction with flanking community members remain largely unknown. Here, we applied meta-omics (i.e., metagenomics, metatranscriptomics and metaproteomics) to the nitrate-reducing iron(II)-oxidizing enrichment culture KS, growing under autotrophic compared to heterotrophic conditions, and originating from a freshwater sediment. We constructed four metagenome-assembled genomes with an estimated completeness of ≥95%, including the key players of NRFO in culture KS, identified as Gallionellaceae sp. and Rhodanobacter sp. The presence of Gallionellaceae sp. and Rhodanobacter sp. transcripts and proteins likely involved in iron(II) oxidation (e.g., mtoAB, cyc2, mofA), denitrification (e.g., napGHI) and oxidative phosphorylation (e.g., respiratory chain complexes I-V), along with Gallionellaceae sp. transcripts and proteins for carbon fixation (e.g., rbcL) were detected. Overall, our results indicate that in culture KS, the Gallionellaceae sp. and Rhodanobacter sp. are interdependent: while Gallionellaceae sp. fixes CO2 and provides organic compounds for Rhodanobacter sp., Rhodanobacter sp. likely detoxifies NO through NO reduction and completes denitrification, which cannot be done by Gallionellaceae sp. alone. Additionally, the transcripts and partial proteins of cbb3- and aa3- type cytochrome c suggest the possibility for a microaerophilic lifestyle of the Gallionellaceae sp., yet culture KS grows under anoxic conditions. Our findings demonstrate that autotrophic NRFO is performed through cooperation among denitrifying and iron(II)-oxidizing bacteria, which might resemble microbial interactions in freshwater environments. Importance Nitrate-reducing iron(II)-oxidizing bacteria are widespread in the environment, contribute to nitrate removal, and influence the fate of the greenhouse gases nitrous oxide and carbon dioxide. The autotrophic growth of nitrate-reducing iron(II)-oxidizing bacteria is rarely investigated and not fully understood. The most prominent model system for this type of studies is the enrichment culture KS. To gain insights into the metabolism of nitrate reduction coupled to iron(II) oxidation in the absence of organic carbon and oxygen, we performed metagenomic, metatranscriptomic and metaproteomic analyses of culture KS, and identified Gallionellaceae sp. and Rhodanobacter sp. as interdependent key iron(II)-oxidizers in culture KS. Our work demonstrates that autotrophic nitrate reduction coupled to iron(II) oxidation is not performed by an individual strain but a cooperation of at least two members of the bacterial community in culture KS. These findings serve as foundation for our understanding of nitrate-reducing iron(II)-oxidizing bacteria in the environment.

scholarly journals Conventional myelosuppressive chemotherapy for non-haematological malignancy disrupts the intestinal microbiome

BMC Cancer ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Lito E. Papanicolas ◽  
Sarah K. Sims ◽  
Steven L. Taylor ◽  
Sophie J. Miller ◽  
Christos S. Karapetis ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Relative Abundance ◽  
Haematological Malignancy ◽  
Amplicon Sequencing ◽  
Intestinal Microbiome ◽  
Rrna Gene ◽  
Conventional Chemotherapy ◽  
Myelosuppressive Chemotherapy ◽  
Gram Positive Bacteria ◽  
Faecal Samples

Abstract Background The gut microbiota influences many aspects of host physiology, including immune regulation, and is predictive of outcomes in cancer patients. However, whether conventional myelosuppressive chemotherapy affects the gut microbiota in humans with non-haematological malignancy, independent of antibiotic exposure, is unknown. Methods Faecal samples from 19 participants with non-haematological malignancy, who were receiving conventional chemotherapy regimens but not antibiotics, were examined prior to chemotherapy, 7–12 days after chemotherapy, and at the end of the first cycle of treatment. Gut microbiota diversity and composition was determined by 16S rRNA gene amplicon sequencing. Results Compared to pre-chemotherapy samples, samples collected 7–12 days following chemotherapy exhibited increased richness (mean 120 observed species ± SD 38 vs 134 ± 40; p = 0.007) and diversity (Shannon diversity: mean 6.4 ± 0.43 vs 6.6 ± 0.41; p = 0.02). Composition was significantly altered, with a significant decrease in the relative abundance of gram-positive bacteria in the phylum Firmicutes (pre-chemotherapy median relative abundance [IQR] 0.78 [0.11] vs 0.75 [0.11]; p = 0.003), and an increase in the relative abundance of gram-negative bacteria (Bacteroidetes: median [IQR] 0.16 [0.13] vs 0.21 [0.13]; p = 0.01 and Proteobacteria: 0.015 [0.018] vs 0.03 [0.03]; p = 0.02). Differences in microbiota characteristics from baseline were no longer significant at the end of the chemotherapy cycle. Conclusions Conventional chemotherapy results in significant changes in gut microbiota characteristics during the period of predicted myelosuppression post-chemotherapy. Further study is indicated to link microbiome changes during chemotherapy to clinical outcomes.

scholarly journals Gut Microbiome and Metabolome Profiles Associated with High-Fat Diet in Mice

Metabolites ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 482
Author(s):  
Jae-Kwon Jo ◽  
Seung-Ho Seo ◽  
Seong-Eun Park ◽  
Hyun-Woo Kim ◽  
Eun-Ju Kim ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Relative Abundance ◽  
High Fat Diet ◽  
Amplicon Sequencing ◽  
Gas Chromatography Mass Spectrometry ◽  
Control Group ◽  
Rrna Gene ◽  
High Fat ◽  
Underlying Mechanisms ◽  
Insight Into

Obesity can be caused by microbes producing metabolites; it is thus important to determine the correlation between gut microbes and metabolites. This study aimed to identify gut microbiota-metabolomic signatures that change with a high-fat diet and understand the underlying mechanisms. To investigate the profiles of the gut microbiota and metabolites that changed after a 60% fat diet for 8 weeks, 16S rRNA gene amplicon sequencing and gas chromatography-mass spectrometry (GC-MS)-based metabolomic analyses were performed. Mice belonging to the HFD group showed a significant decrease in the relative abundance of Bacteroidetes but an increase in the relative abundance of Firmicutes compared to the control group. The relative abundance of Firmicutes, such as Lactococcus, Blautia, Lachnoclostridium, Oscillibacter, Ruminiclostridium, Harryflintia, Lactobacillus, Oscillospira, and Erysipelatoclostridium, was significantly higher in the HFD group than in the control group. The increased relative abundance of Firmicutes in the HFD group was positively correlated with fecal ribose, hypoxanthine, fructose, glycolic acid, ornithine, serum inositol, tyrosine, and glycine. Metabolic pathways affected by a high fat diet on serum were involved in aminoacyl-tRNA biosynthesis, glycine, serine and threonine metabolism, cysteine and methionine metabolism, glyoxylate and dicarboxylate metabolism, and phenylalanine, tyrosine, and trypto-phan biosynthesis. This study provides insight into the dysbiosis of gut microbiota and metabolites altered by HFD and may help to understand the mechanisms underlying obesity mediated by gut microbiota.

scholarly journals Relative and quantitative rhizosphere microbiome profiling result in distinct abundance patterns

2021 ◽  
Author(s):  
Hamed Azarbad ◽  
Julien Tremblay ◽  
Luke D. Bainard ◽  
Etienne Yergeau
Keyword(s):  
Water Stress ◽  
Relative Abundance ◽  
Its Region ◽  
Cost Effective ◽  
Amplicon Sequencing ◽  
Rrna Gene ◽  
Real Time Quantitative Pcr ◽  
Rhizosphere Microbiome ◽  
History Of ◽  
Almost All

AbstractNext-generation sequencing is recognized as one of the most popular and cost-effective way of characterizing microbiome in multiple samples. However, most of the currently available amplicon sequencing approaches are inherently limited, as they are often presented based on the relative abundance of microbial taxa, which may not fully represent actual microbiome profiles. Here, we combined amplicon sequencing (16S rRNA gene for bacteria and ITS region for fungi) with real-time quantitative PCR (qPCR) to characterize the rhizosphere microbiome of wheat. We show that the increase in relative abundance of major microbial phyla does not necessarily result in an increase in abundance. One striking observation when comparing relative and quantitative abundances was a substantial increase in the abundance of almost all phyla associated with the rhizosphere of plants grown in soil with no history of water stress as compared with the rhizosphere of plants growing in soil with a history of water stress, which was in contradiction with the trends observed in the relative abundance data. Our results suggest that the estimated absolute abundance approach gives a different perspective than the relative abundance approach, providing complementary information that helps to better understand the rhizosphere microbiome.

scholarly journals The human gut archaeome: identification of diverse haloarchaea in Korean subjects

2020 ◽  
Author(s):  
Joon Yong Kim ◽  
Tae Woong Whon ◽  
Mi Young Lim ◽  
Yeon Bee Kim ◽  
Namhee Kim ◽  
...  
Keyword(s):  
Relative Abundance ◽  
Quantitative Polymerase Chain Reaction ◽  
Rrna Gene ◽  
Limited Information ◽  
Human Gut ◽  
Individual Variations ◽  
Faecal Samples ◽  
Hybridisation Analysis ◽  
Archaeal Communities

Abstract Background: Archaea are one of the least-studied members of the gut-dwelling autochthonous microbiota. Few studies have reported the dominance of methanogens in the archaeal microbiome (archaeome) of the human gut, although limited information regarding the diversity and abundance of other archaeal phylotypes is available.Results: We surveyed the archaeome of faecal samples collected from 897 East Asian subjects living in South Korea. In total, 42.47% faecal samples were positive for archaeal colonisation; these were subsequently subjected to archaeal 16S rRNA gene deep sequencing and real-time quantitative polymerase chain reaction-based abundance estimation. The mean archaeal relative abundance was 10.24% ± 4.58% of the total bacterial and archaeal abundance. We observed extensive colonisation of haloarchaea (95.54%) in the archaea-positive faecal samples, with 9.63% mean relative abundance in archaeal communities. Haloarchaea were relatively more abundant than methanogens in some samples. The presence of haloarchaea was also verified by fluorescence in situ hybridisation analysis. Owing to large inter-individual variations, we categorised the human gut archaeome into four archaeal enterotypes.Conclusions: The study demonstrated that the human gut archaeome is indigenous, responsive, and functional, expanding our understanding of the archaeal signature in the gut of human individuals.

scholarly journals Microbial Communities on Plastic Polymers in the Mediterranean Sea

2021 ◽  
Vol 12 ◽  
Author(s):  
Annika Vaksmaa ◽  
Katrin Knittel ◽  
Alejandro Abdala Asbun ◽  
Maaike Goudriaan ◽  
Andreas Ellrott ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Mediterranean Sea ◽  
Amplicon Sequencing ◽  
Polymer Surfaces ◽  
Rrna Gene ◽  
Sequencing Data ◽  
Microbial Biofilms ◽  
Degrading Bacteria ◽  
The Mediterranean

Plastic particles in the ocean are typically covered with microbial biofilms, but it remains unclear whether distinct microbial communities colonize different polymer types. In this study, we analyzed microbial communities forming biofilms on floating microplastics in a bay of the island of Elba in the Mediterranean Sea. Raman spectroscopy revealed that the plastic particles mainly comprised polyethylene (PE), polypropylene (PP), and polystyrene (PS) of which polyethylene and polypropylene particles were typically brittle and featured cracks. Fluorescence in situ hybridization and imaging by high-resolution microscopy revealed dense microbial biofilms on the polymer surfaces. Amplicon sequencing of the 16S rRNA gene showed that the bacterial communities on all plastic types consisted mainly of the orders Flavobacteriales, Rhodobacterales, Cytophagales, Rickettsiales, Alteromonadales, Chitinophagales, and Oceanospirillales. We found significant differences in the biofilm community composition on PE compared with PP and PS (on OTU and order level), which shows that different microbial communities colonize specific polymer types. Furthermore, the sequencing data also revealed a higher relative abundance of archaeal sequences on PS in comparison with PE or PP. We furthermore found a high occurrence, up to 17% of all sequences, of different hydrocarbon-degrading bacteria on all investigated plastic types. However, their functioning in the plastic-associated biofilm and potential role in plastic degradation needs further assessment.

scholarly journals Growth and Population Dynamics of the Anaerobic Fe(II)-Oxidizing and Nitrate-Reducing Enrichment Culture KS

2018 ◽  
Vol 84 (9) ◽  
Author(s):  
Claudia Tominski ◽  
Helene Heyer ◽  
Tina Lösekann-Behrens ◽  
Sebastian Behrens ◽  
Andreas Kappler
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Community Composition ◽  
Enrichment Culture ◽  
Operational Taxonomic Unit ◽  
Amplicon Sequencing ◽  
Rrna Gene ◽  
Organic Substrates ◽  
Content Type ◽  
Heterotrophic Denitrification

ABSTRACTMost isolated nitrate-reducing Fe(II)-oxidizing microorganisms are mixotrophic, meaning that Fe(II) is chemically oxidized by nitrite that forms during heterotrophic denitrification, and it is debated to which extent Fe(II) is enzymatically oxidized. One exception is the chemolithoautotrophic enrichment culture KS, a consortium consisting of a dominant Fe(II) oxidizer,Gallionellaceaesp., and less abundant heterotrophic strains (e.g.,Bradyrhizobiumsp.,Nocardioidessp.). Currently, this is the only nitrate-reducing Fe(II)-oxidizing culture for which autotrophic growth has been demonstrated convincingly for many transfers over more than 2 decades. We used 16S rRNA gene amplicon sequencing and physiological growth experiments to analyze the community composition and dynamics of culture KS with various electron donors and acceptors. Under autotrophic conditions, an operational taxonomic unit (OTU) related to known microaerophilic Fe(II) oxidizers within the familyGallionellaceaedominated culture KS. With acetate as an electron donor, most 16S rRNA gene sequences were affiliated withBradyrhizobiumsp.Gallionellaceaesp. not only was able to oxidize Fe(II) under autotrophic and mixotrophic conditions but also survived over several transfers of the culture on only acetate, although it then lost the ability to oxidize Fe(II).Bradyrhizobiumspp. became and remained dominant when culture KS was cultivated for only one transfer under heterotrophic conditions, even when conditions were reverted back to autotrophic in the next transfer. This study showed a dynamic microbial community in culture KS that responded to changing substrate conditions, opening up questions regarding carbon cross-feeding, metabolic flexibility of the individual strains in KS, and the mechanism of Fe(II) oxidation by a microaerophile in the absence of O2.IMPORTANCENitrate-reducing Fe(II)-oxidizing microorganisms are present in aquifers, soils, and marine and freshwater sediments. Most nitrate-reducing Fe(II) oxidizers known are mixotrophic, meaning that they need organic carbon to continuously oxidize Fe(II) and grow. In these microbes, Fe(II) was suggested to be chemically oxidized by nitrite that forms during heterotrophic denitrification, and it remains unclear whether or to what extent Fe(II) is enzymatically oxidized. In contrast, the enrichment culture KS was shown to oxidize Fe(II) autotrophically coupled to nitrate reduction. This culture contains the designated Fe(II) oxidizerGallionellaceaesp. and several heterotrophic strains (e.g.,Bradyrhizobiumsp.). We showed that culture KS is able to metabolize Fe(II) and a variety of organic substrates and is able to adapt to dynamic environmental conditions. When the community composition changed andBradyrhizobiumbecame the dominant community member, Fe(II) was still oxidized byGallionellaceaesp., even when culture KS was cultivated with acetate/nitrate [Fe(II) free] before being switched back to Fe(II)/nitrate.

scholarly journals Complementing 16S rRNA Gene Amplicon Sequencing with Total Bacterial Load To Infer Absolute Species Concentrations in the Vaginal Microbiome

mSystems ◽  
2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Florencia A. Tettamanti Boshier ◽  
Sujatha Srinivasan ◽  
Anthony Lopez ◽  
Noah G. Hoffman ◽  
Sean Proll ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Relative Abundance ◽  
Bacterial Species ◽  
Bacterial Load ◽  
Amplicon Sequencing ◽  
Individual Species ◽  
Rrna Gene ◽  
Vaginal Microbiome ◽  
Bacterial Concentrations

ABSTRACT Whereas 16S rRNA gene amplicon sequencing quantifies relative abundances of bacterial taxa, variation in total bacterial load between samples restricts its ability to reflect absolute concentrations of individual bacterial species. Quantitative PCR (qPCR) can quantify individual species, but it is not practical to develop a suite of qPCR assays for every bacterium present in a diverse sample. We sought to determine the accuracy of an inferred measure of bacterial concentration using total bacterial load and relative abundance. We analyzed 1,320 samples from 20 women with a history of frequent bacterial vaginosis who self-collected vaginal swabs daily over 60 days. We inferred bacterial concentrations by taking the product of species relative abundance (assessed by 16S rRNA gene amplicon sequencing) and bacterial load (measured by broad-range 16S rRNA gene qPCR). Log10-converted inferred concentrations correlated with targeted qPCR (r = 0. 935, P < 2.2e–16) for seven key bacterial species. The mean inferred concentration error varied across bacteria, with rarer bacteria associated with larger errors. A total of 92% of the >0.5-log10 errors occurred when the relative abundance was <10%. Many errors occurred during early bacterial expansion from or late contraction to low abundance. When the relative abundance of a species is >10%, inferred concentrations are reliable proxies for targeted qPCR in the vaginal microbiome. However, targeted qPCR is required to capture bacteria at low relative abundance and is preferable for characterizing growth and decay kinetics of single species. IMPORTANCE Microbiome studies primarily use 16S rRNA gene amplicon sequencing to assess the relative abundance of bacterial taxa in a community. However, these measurements do not accurately reflect absolute taxon concentrations. We sought to determine whether the product of species’ relative abundance and total bacterial load measured by broad-range qPCR is an accurate proxy for individual species’ concentrations, as measured by taxon-specific qPCR assays. Overall, the inferred bacterial concentrations were a reasonable proxy of species-specific qPCR values, particularly when bacteria are present at a higher relative abundance. This approach offers an opportunity to assess the concentrations of bacterial species and how they change in a community over time without developing individual qPCR assays for each taxon.

scholarly journals Microbiota Assembly, Structure, and Dynamics Among Tsimane Horticulturalists of the Bolivian Amazon

2019 ◽  
Author(s):  
Daniel D. Sprockett ◽  
Melanie Martin ◽  
Elizabeth K. Costello ◽  
Adam Burns ◽  
Susan P. Holmes ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Relative Abundance ◽  
Market Integration ◽  
Market Access ◽  
Amplicon Sequencing ◽  
Rrna Gene ◽  
Cultural Changes ◽  
Neutral Processes ◽  
Oral Microbes ◽  
Access To Medical Care

ABSTRACTLittle is known about the relative contributions of selective and neutral forces on human-associated microbiota assembly. Here, we characterize microbial community assembly in 52 Tsimane infant-mother pairs, using longitudinally collected stool and tongue swab samples profiled with 16S rRNA gene amplicon sequencing. The Tsimane are an indigenous Bolivian population who practice infant care associated behaviors expected to increase mother-infant dispersal. Infant consumption of dairy products, vegetables, and chicha (a fermented drink inoculated with oral microbes) was significantly associated with gut microbiota composition. At both body sites, maternal microbes at higher relative abundance were more likely to be shared. Shared microbes were also higher in abundance in infants at both body sites, but decreased in average relative abundance with age and were not significantly higher by 12 months of age. Infant microbiotas were modeled using a neutral community model of assembly, which showed that the prevalence of more than two thirds of infant-colonizing microbes could be explained using neutral processes alone. The same method was applied to datasets from Finnish and Bangladeshi infants, confirming that the majority of microbes colonizing infants from different countries were neutrally distributed. Among the Tsimane infant and adult gut microbiota samples, neutral processes were less prominent in villages with more market access. These results underscore the importance of neutral processes during infant microbiota assembly, and suggest that cultural changes associated with market integration may be affecting traditional modes of microbiota assembly by decreasing the role of these neutral processes, perhaps through changes in diet, sanitation, or access to medical care.

scholarly journals Assessing the Risks of Potential Bacterial Pathogens Attaching to Different Microplastics during the Summer–Autumn Period in a Mariculture Cage

2021 ◽  
Vol 9 (9) ◽  
pp. 1909
Author(s):  
Dandi Hou ◽  
Man Hong ◽  
Yanting Wang ◽  
Pengsheng Dong ◽  
Huangwei Cheng ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Amplicon Sequencing ◽  
Rrna Gene ◽  
Autumn Period ◽  
Aquatic Product ◽  
In Situ Incubation ◽  
Custom Made ◽  
Potential Risks ◽  
Surrounding Seawater

As microplastic pollution continues to increase, an emerging threat is the potential for microplastics to act as novel substrates and/or carriers for pathogens. This is of particular concern for aquatic product safety given the growing evidence of microplastic ingestion by aquaculture species. However, the potential risks of pathogens associated with microplastics in mariculture remain poorly understood. Here, an in situ incubation experiment involving three typical microplastics including polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP) was conducted during the summer–autumn period in a mariculture cage. The identification of potential pathogens based on the 16S rRNA gene amplicon sequencing and a custom-made database for pathogenic bacteria involved in aquatic environments, was performed to assess the risks of different microplastics attaching potential pathogens. The enrichment of pathogens was not observed in microplastic-associated communities when compared with free-living and particle-attached communities in surrounding seawater. Despite the lower relative abundance, pathogens showed different preferences for three microplastic substrates, of which PET was the most favored by pathogens, especially potentially pathogenic members of Vibrio, Tenacibaculum, and Escherichia. Moreover, the colonization of these pathogens on microplastics was strongly affected by environmental factors (e.g., temperature, nitrite). Our results provide insights into the ecological risks of microplastics in mariculture industry.

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