Deciphering biodiversity and interactions between bacteria and microeukaryotes within epilithic biofilms from the Loue River, France

Abstract

Epilithic river biofilms are complex matrix-enclosed communities harboring a great diversity of prokaryotic and eukaryotic microorganisms. Interactions between these communities and the relative impacts of environmental factors on their compositions are poorly understood. In this study, we assessed the spatio-temporal variation in the diversity and composition of bacterial and microeukaryotic communities within biofilms in a French river. Significant changes were found in the composition of these microbial communities over the sampling period and between the upstream and downstream stations. In addition, the beta diversity of the bacterial community tended to decrease along the river, mostly as a result of turnover. These changes could be caused by the different water temperatures and geological and hydrological river contexts at the sampling sites (from karst landscape to river plain). Finally, our network analysis showed multiple correlations among dominant OTUs. Among them, negative correlations between Rhodobacteraceae and two other dominant groups of photosynthetic microorganisms (cyanobacteria and diatoms) were particularly interesting, which raises the question of what environmental factors trigger the changes occurring in benthic microbial photosynthetic communities.

The princess and the pea: seasonal development of the desmid Oocardium stratum along a limestone-precipitating spring stream

“…Proportions of green algae, diatoms and Cyanobacteria were comparable to former studies on epilithic biofilms in alpine regions, with diatoms being the dominant photosynthetic group followed by Cyanobacteria and green algae (Zancarini et al 2017). We observed an initial colonisation by diatoms and cyanobacteria; O. stratum growth was delayed (Figs 4-5, 9-11).…”

“…In contrast, diatoms were linked neither to spatial (site) nor to temporal (season) factors. Except for site M during late autumn, this group dominated the photoautotrophic biofilm (Table S5), which agrees with Zancarini et al (2017).…”

“…We assume that extracellular polymeric substances excreted by pioneer microorganisms, i.e. beta proteobacteria and certain diatoms, have a fundamental function in biofilm succession, as this was shown in other stream systems (Battin et al 2003;Besemer et al 2007;Stolz 2000;Zancarini et al 2017). These initial colonisers provide a matrix for subsequent organisms (Roeselers et al 2007;Zancarini et al 2017).…”

Toxic benthic freshwater cyanobacterial proliferations: Challenges and solutions for enhancing knowledge and improving monitoring and mitigation

“…Commercially available quantitative PCR kits are available and have been applied for this purpose in a number of countries (personal communication, Wood and Davis). Advancements in high‐throughput sequencing have seen the widescale application of this technique to characterise the taxonomy of the cyanobacterial mat communities, this includes cyanobacteria, heterotrophic bacteria and eukaryotic algae (Echenique‐Subiabre, Zancarini, et al, 2018; Pessi, Maalouf, Laughinghouse, Baurain, & Wilmotte, 2016; Zancarini et al., 2017). To date, this technique has primarily been applied for research purposes and to our knowledge is not used in any systematic monitoring programmes.…”

Handling the Microbial Complexity Associated to Ticks

“…Network analysis, a branch of graph theory, is a mathematical tool for the analysis of complex systems composed of many components which may interact with each other. Network analysis has been used to unravel complex microbial communities such as those present in soil [33], water [34] and human [35,36] and tick microbiota [37]. This chapter focuses on the impact of high-throughput technologies in the current understanding of the microbial complexity associated to ticks.…”