A high-throughput sequencing ecotoxicology study of freshwater bacterial communities and their responses to tebuconazole

Abstract

The pollution of lakes and rivers by pesticides is a growing problem worldwide. However, the impacts of these substances on microbial communities are still poorly understood, partly because next-generation sequencing (NGS) has rarely been used in an ecotoxicology context to study bacterial communities despite its interest for accessing rare taxa. Microcosm experiments were carried out to evaluate the effects of tebuconazole (TBZ) on the structure and composition of bacterial communities from two types of freshwater ecosystem (lakes and rivers) with differing histories of pollutant contamination (pristine vs. previously exposed sites). Pyrosequencing revealed that bacterial diversity was higher in the river than in the lakes and in previously exposed sites than in pristine sites. Lakes and river stations shared very few OTUs, and differences at the phylum level were identified between these ecosystems (i.e. the relative importance of Actinobacteria and Gammaproteobacteria). Despite differences between these ecosystems and their contamination history, no significant effect of TBZ on bacterial community structure or composition was observed. Compared to functional parameters that displayed variable responses, we demonstrated that a combination of classical methods and NGS is necessary to investigate the ecotoxicological responses of microbial communities to pollutants.

Proteobacteria: microbial signature of dysbiosis in gut microbiota

“…More recently, the development of next-generation sequencing techniques and biological computational tools has allowed cost-effective, large-scale multiplexing analyses, which have transformed our understanding of the interactions between microbial communities and their niche [2][3][4][5][6]. This approach has opened a window onto the enormous taxonomic and functional diversity of the microbial community of the human body, called the microbiota [7].…”

“…As the name suggests, members of the phylum Proteobacteria have greatly variable morphology and versatile physiology, which gives them a competitive edge in surviving in various ecological niches. Proteobacteria has been observed to be ubiquitous in habitats such as soil [2], plants [4], seawater [5], freshwater [3], the atmosphere [6], and mammalian body sites [7,48] ( Figure I). The phylum comprises six bacterial classes: Alpha-, Beta-, Gamma-, Delta-, Epsilon-, and Zetaproteobacteria.…”

Influence of streambed substratum composition on stream microbial communities exposed to the fungicide tebuconazole

“…The fungicide also reduced species richness of aquatic hyphomycetes at all concentrations tested and modified the kinetics of β‐glucosidase, β‐xylosidase and cellobiohydrolase, resulting in slow cellulose degradation by leaf‐associated microorganisms (Artigas et al ., ). TBZ effects on aquatic ecosystems have been also studied in biofilm and plankton microbial communities (Artigas et al ., ; Pascault et al ., ), where different functional indicators showed variable responses to TBZ, whereas bacterial community structure was unaffected. Bacteria associated with decomposing leaves are also inhibited by TBZ, although less than fungi (Bundschuh et al ., ; Artigas et al ., ).…”

Substratum‐Associated Microbiota

“…The increased use of pesticides and novel nanoparticles puts increased stress on aquatic ecosystems, including bacterial biofilms. Pascault et al (2014) combined classical methods and next-generation sequencing to investigate the responses of microbial communities to the pesticide tebuconazole (TBZ). They revealed that bacterial diversity was higher in rivers than in lakes and in previously exposed sites than in pristine sites.…”