RESUMO
Studies on disturbance events in riverine systems caused by environmental disasters and their effects on microbial diversity are scarce. Here, we evaluated the impact of the collapse of an iron ore dam holding approximately 50 million cubic meters of waste on both water and sediment microbiomes by deeply sequencing the 16S rRNA gene. Samples were taken from two impacted rivers and one reference river 7, 30 and 150 days postdisturbance. The impacted community structure changed greatly over spatiotemporal scales, being less diverse and more uneven, particularly on day 7 for the do Carmo River (the closest to the dam). However, the reference community structure remained similar between sampling events. Moreover, the impacted sediments were positively correlated with metals. The taxa abundance varied greatly over spatiotemporal scales, allowing for the identification of several potential bioindicators, e.g., Comamonadaceae, Novosphingobium, Sediminibacterium and Bacteriovorax. Our results showed that the impacted communities consisted mostly of Fe(II) oxidizers and Fe(III) reducers, aromatic compound degraders and predator bacteria. Network analysis showed a highly interconnected microbiome whose interactions switched from positive to negative or vice versa between the impacted and reference communities. This work revealed potential molecular signatures associated with the rivers heavily impacted by metals that might be useful sentinels for predicting riverine health.
Assuntos
Monitoramento Ambiental , Microbiota , Mineração , Rios/microbiologia , Poluentes Químicos da Água/análise , Bactérias/genética , Bacteroidetes/genética , Compostos Férricos/análise , Sedimentos Geológicos/química , RNA Ribossômico 16S/genética , Rios/química , Esgotos/análise , TsunamisRESUMO
Bacterioplankton communities have a pivotal role in the global carbon cycle. Still the interaction between microbial community and dissolved organic matter (DOM) in freshwater ecosystems remains poorly understood. Here, we report results from a 12-day mesocosm study performed in the epilimnion of a tropical lake, in which inorganic nutrients and allochthonous DOM were supplemented under full light and shading. Although the production of autochthonous DOM triggered by nutrient addition was the dominant driver of changes in bacterial community structure, temporal covariations between DOM optical proxies and bacterial community structure revealed a strong influence of community shifts on DOM fate. Community shifts were coupled to a successional stepwise alteration of the DOM pool, with different fractions being selectively consumed by specific taxa. Typical freshwater clades as Limnohabitans and Sporichthyaceae were associated with consumption of low molecular weight carbon, whereas Gammaproteobacteria and Flavobacteria utilized higher molecular weight carbon, indicating differences in DOM preference among clades. Importantly, Verrucomicrobiaceae were important in the turnover of freshly produced autochthonous DOM, ultimately affecting light availability and dissolved organic carbon concentrations. Our findings suggest that taxonomically defined bacterial assemblages play definite roles when influencing DOM fate, either by changing specific fractions of the DOM pool or by regulating light availability and DOC levels.
Assuntos
Bactérias/crescimento & desenvolvimento , Monitoramento Ambiental , Substâncias Húmicas/análise , Lagos/microbiologia , Microbiologia da Água , Poluentes da Água/análise , Organismos Aquáticos , Carbono , Ecossistema , Lagos/química , Clima TropicalRESUMO
Water hyacinth (WH), a large floating plant, plays an important role in the biogeochemistry and ecology of many freshwaters globally. Its biogeochemical impact on wetland functioning is strongly mediated by the microbiome associated with its roots. However, little is known about the structure and function of this WH rhizobiome and its relation to wetland ecosystem functioning. Here, we unveil the core and transient rhizobiomes of WH and their key biogeochemical functions in two of the world's largest wetlands: the Amazon and the Pantanal. WH hosts a highly diverse microbial community shaped by spatiotemporal changes. Proteobacteria lineages were most common, followed by Actinobacteria and Planctomycetes. Deltaproteobacteria and Sphingobacteriia predominated in the core microbiome, potentially associated with polysaccharide degradation and fermentation of plant-derived carbon. Conversely, a plethora of lineages were transient, including highly abundant Acinetobacter, Acidobacteria subgroup 6, and methanotrophs, thus assuring diverse taxonomic signatures in the two different wetlands. Our findings point out that methanogenesis is a key driver of, and proxy for, community structure, especially during seasonal plant decline. We provide ecologically relevant insights into the WH microbiome, which is a key element linking plant-associated carbon turnover with other biogeochemical fluxes in tropical wetlands.
Assuntos
Bactérias/isolamento & purificação , Bactérias/metabolismo , Carbono/metabolismo , Eichhornia/microbiologia , Microbiota , Bactérias/classificação , Bactérias/genética , DNA Bacteriano/genética , Ecossistema , Nutrientes/metabolismo , Filogenia , RNA Ribossômico 16S/genéticaRESUMO
Leprosy is a chronic infectious peripheral neuropathy that is caused by Mycobacterium leprae, and the skin is one of its preferred target sites. However, the effects of this infection on the skin microbiome remain largely unexplored. Here, we characterize and compare the lesional and non-lesional skin microbiomes of leprosy patients and healthy individuals through the deep sequencing of 16 S rRNA genes. Additionally, a subset of patients was monitored throughout the multi-drug therapy to investigate its effect on the leprous skin microbiome. Firmicutes-associated OTUs (primarily Staphylococcus) prevailed in healthy individuals. By contrast, Firmicutes was underrepresented and Proteobacteria was enriched in the patients' skin, although a single dominant taxon has not been observed at a finer taxonomic resolution. These differences can be explained by the significant decrease in Staphylococcus and Streptococcus as well as the enrichment in Brevundimonas. The overrepresentation of Micrococcus in patients is also remarkable. Genus-level compositional profiles revealed no significant intrapersonal difference between lesional and non-lesional sites. Treatment-associated changes indicated a loss of diversity and a shift in the community composition, with stronger impacts on the OTUs that are considered indigenous bacteria. Therefore, the molecular signatures associated with leprosy identified herein might be of importance for early diagnostics.
Assuntos
Bactérias/isolamento & purificação , Hanseníase/microbiologia , Microbiota , Pele/microbiologia , Antibacterianos/uso terapêutico , Bactérias/classificação , Bactérias/genética , Brasil/epidemiologia , Firmicutes/classificação , Firmicutes/genética , Firmicutes/isolamento & purificação , Humanos , Hanseníase/tratamento farmacológico , Hanseníase/epidemiologia , Microbiota/efeitos dos fármacos , Mycobacterium leprae/efeitos dos fármacos , Estudos Prospectivos , Proteobactérias/classificação , Proteobactérias/genética , Proteobactérias/isolamento & purificaçãoRESUMO
Gut microbiota exerts a fundamental role on host physiology, and how extrinsic perturbations influence its composition has been increasingly examined. However, the effect of drinking water on gut microbiota is still poorly understood. In this study, we explored the response of mouse gut bacterial community (fecal and mucosa-adhered) to the ingestion of different types of drinking water. The experimental cohort was divided according to different water sources into four groups of mice that consumed autoclaved tap water (control group), water collected directly from a drinking water treatment plant, tap water, and commercial bottled mineral water. Differences among groups were observed, especially related to control group, which exhibited the smallest intra-group variation, and the largest distance from test groups on the last experimental day. Clinically important taxa, such as Acinetobacter and Staphylococcus, increased in feces of mice that drank tap water and in mucosa-adhered samples of animals from disinfected and tap water groups. Furthermore, statistical analyses showed that both time elapsed between samplings and water type significantly influenced the variation observed in the samples. Our results reveal that drinking water potentially affects gut microbiota composition. Additionally, the increase of typical drinking water clinically relevant and antibiotic resistance-associated bacteria in gut microbiota is a cause of concern.
Assuntos
Bactérias/classificação , Água Potável , Microbioma Gastrointestinal , Águas Minerais , Animais , Desinfecção , Fezes/microbiologia , Feminino , Camundongos Endogâmicos BALB C , Purificação da Água , Abastecimento de ÁguaRESUMO
Bacteria are essential in arsenic cycling. However, few studies have addressed 16S rRNA and arsenic-related functional gene diversity in long-term arsenic-contaminated tropical sediment. Here, using culture-based, metagenomic and computational approaches, we describe the diversity of bacteria, genes and enzymes involved in AsIII and AsV transformation in freshwater sediment and in anaerobic AsIII- and AsV-enrichment cultures (ECs). The taxonomic profile reveals significant differences among the communities. Arcobacter, Dechloromonas, Sedimentibacter and Clostridium thermopalmarium were exclusively found in ECs, whereas Anaerobacillus was restricted to AsV-EC. Novel taxa that are both AsV-reducers and AsIII-oxidizers were identified: Dechloromonas, Acidovorax facilis, A. delafieldii, Aquabacterium, Shewanella, C. thermopalmarium and Macellibacteroides fermentans. Phylogenic discrepancies were revealed among the aioA, arsC and arrA genes and those of other species, indicating horizontal gene transfer. ArsC and AioA have sets of amino acids that can be used to assess their functional and structural integrity and familial subgroups. The positions required for AsV reduction are conserved, suggesting strong selective pressure for maintaining the functionality of ArsC. Altogether, these findings highlight the role of freshwater sediment bacteria in arsenic mobility, and the untapped diversity of dissimilatory arsenate-reducing and arsenate-resistant bacteria, which might contribute to arsenic toxicity in aquatic environments.
Assuntos
Arsênio/metabolismo , Bactérias/classificação , Água Doce/microbiologia , Variação Genética , Sedimentos Geológicos/microbiologia , Redes e Vias Metabólicas/genética , Poluentes Químicos da Água/metabolismo , Anaerobiose , Bactérias/genética , Bactérias/isolamento & purificação , Biotransformação , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Enzimas/genética , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNARESUMO
PURPOSE: Class 1 integrons are among the main vehicles that facilitate the spread of antibiotic-resistance genes, with serious public health consequences. The aim of this cross-sectional study was to investigate the presence of class 1 integrons and to characterize their variable regions, as well as the antimicrobial resistance profiles and phylogenetic groups of a collection of Escherichia coli isolates recovered from healthy subjects (n=42) and those with urinary infection (n=40). METHODOLOGY: The methods used included PCR, sequencing and antimicrobial susceptibility testing. RESULTS: PCR screening for the integrase gene (intI1) revealed a higher incidence of class 1 integrons in uropathogenic E. coli (65â%, UPEC) than in commensal isolates (11.9â%). Eight of 31 intI1-positive isolates, all of them UPEC, harboured empty integrons. The variable regions of the other 23 contained gene cassettes encoding resistance to ß-lactams (blaOXA-1), aminoglycosides (aadA1 and aadA5), trimethoprim (dfrA1 and dfrA17) and an ORF. To our knowledge this is the first report of an ORF identified as a putative phage tail protein associated with a class 1 integron. The aadA1 and dfrA17-addA5 arrays prevailed in commensal E. coli and UPEC, respectively. UPEC isolates were highly resistant to the antimicrobials tested, in contrast to commensal isolates. The E. coli isolates carrying gene cassettes associated with class 1 integrons were found to be unrelated to any phylogroup or multiresistance. CONCLUSION: Co-resistance to clinically relevant fluoroquinolone and trimethoprim-sulfamethazole in all UPEC isolates is a cause for concern. These results expand the current knowledge of gene cassettes in both commensal and pathogenic E. coli.
Assuntos
Infecções por Escherichia coli/microbiologia , Proteínas de Escherichia coli/genética , Escherichia coli/genética , Integrons , Infecções Urinárias/microbiologia , Escherichia coli Uropatogênica/genética , Antibacterianos/farmacologia , Estudos Transversais , Farmacorresistência Bacteriana/genética , Escherichia coli/efeitos dos fármacos , Infecções por Escherichia coli/epidemiologia , Fezes/microbiologia , Humanos , Fenótipo , Filogenia , Reação em Cadeia da Polimerase , Simbiose/genética , Escherichia coli Uropatogênica/efeitos dos fármacosRESUMO
Wastewater treatment plants (WWTPs) harbor bacteria and antimicrobial resistance genes, favoring gene exchange events and resistance dissemination. Here, a culture-based and metagenomic survey of qnrA, qnrB, qnrS, and aac(6')-Ib genes from raw sewage (RS) and activated sludge (AS) of a full-scale municipal WWTP was performed. A total of 96 bacterial isolates were recovered from nalidixic acid-enrichment cultures. Bacteria harboring the aac(6')-Ib gene predominated in RS, whereas qnrS-positive isolates were specific to AS. Novel qnrS- and aac(6')-Ib-cr positive species were identified: Morganella morganii, Providencia rettgeri, and Pseudomonas guangdongensis (qnrS), and Alcaligenes faecalis and P. rettgeri (aac(6')-Ib-cr). Analysis of qnrS and aac(6')-Ib sequences from isolates and clone libraries suggested that the diversity of qnrS is wider than that of aac(6')-Ib. A large number of amino acid mutations were observed in the QnrS and AAC(6')-Ib proteins at previously undetected positions, whose structural implications are not clear. An accumulation of mutations at the C72, Q73, L74, A75 and M76 positions of QnrS, and D181 of AAC(6')-Ib might be important for resistance. These findings add significant information on bacteria harboring qnrS and aac(6')-Ib genes, and the presence of novel mutations that may eventually emerge in clinical isolates.
Assuntos
Escherichia coli/isolamento & purificação , Esgotos , Antibacterianos/farmacologia , Farmacorresistência Bacteriana/genética , Fluoroquinolonas , Testes de Sensibilidade Microbiana , Mutação , Plasmídeos/efeitos dos fármacos , QuinolonasRESUMO
Bacteria from aquatic ecosystems significantly contribute to biogeochemical cycles, but details of their community structure in tropical mining-impacted environments remain unexplored. In this study, we analyzed a bacterial community from circumneutral-pH tropical stream sediment by 16S rRNA and shotgun deep sequencing. Carrapatos stream sediment, which has been exposed to metal stress due to gold and iron mining (21 [g Fe]/kg), revealed a diverse community, with predominance of Proteobacteria (39.4%), Bacteroidetes (12.2%), and Parcubacteria (11.4%). Among Proteobacteria, the most abundant reads were assigned to neutrophilic iron-oxidizing taxa, such as Gallionella, Sideroxydans, and Mariprofundus, which are involved in Fe cycling and harbor several metal resistance genes. Functional analysis revealed a large number of genes participating in nitrogen and methane metabolic pathways despite the low concentrations of inorganic nitrogen in the Carrapatos stream. Our findings provide important insights into bacterial community interactions in a mining-impacted environment.
Assuntos
Bactérias/metabolismo , Redes e Vias Metabólicas/efeitos dos fármacos , Mineração , Rios , Microbiologia da Água , Bactérias/classificação , Bactérias/genética , Bacteroidetes/classificação , Bacteroidetes/genética , Bacteroidetes/metabolismo , Brasil , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiologia , Ferro/análise , Ferro/metabolismo , Metagenômica , Filogenia , Proteobactérias/classificação , Proteobactérias/genética , Proteobactérias/metabolismo , RNA Ribossômico 16S/genética , Rios/química , Rios/microbiologia , Clima Tropical , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/metabolismoRESUMO
The integron-gene cassette system has typically been associated with antibiotic-resistant pathogens. However, the diversity of gene cassettes and the abundance of class 1 integrons outside of the clinical context are not fully explored. Primers targeting the conserved segments of attC recombination sites were used to amplify gene cassettes from the sediment of the Mina stream, which exhibited a higher degree of stress to metal pollution in the dry season than the rainy season. Of the 143 total analyzed sequences, 101 had no matches to proteins in the database, where cassette open reading frames could be identified by homology with database entries. There was a predominance of sequences encoding essential cellular functions. Each season that was sampled yielded a specific pool of gene cassettes. Real-time PCR revealed that 8.5 and 41.6 % of bacterial cells potentially harbored a class 1 integron in the rainy and dry seasons, respectively. In summary, our findings demonstrate that most of the gene cassettes have no ascribable function and, apparently, historically metal-contaminated sediment favors the maintenance of bacteria containing the intI1 gene. Thus, the diversity of gene cassettes is far from being fully explored deserving further attention.