ABSTRACT: Bacterial community composition of size-fractioned aggregates within the phycosphere of cyanobacterial blooms in one eutrophicfreshwater lake Genome sequencing
Project description:<p>Cyanobacterial blooms result from continued short-term succession of planktonic microbiomes, but these short-term variations are little known. Here we address this question with a field diel study in Lake Tai. By integrating untargeted metabolomics—verified by targeted metabolomics—and metagenomics, we reveal the diel cycle of planktonic microbiome in Lake Tai are highly dynamic and complex. First, metabolite abundance and their molecular mass display clear diel changes along with shift in the taxon abundance and biological functions, following the same environmental factors. Some taxa and biological functions (reactions) are highly correlated with the metabolite abundance, and large compounds appear to be more taxon specific. Second, phytoplanktonic and overall planktonic microbiome showed different temporal variation of abundance, opposite levels of abundance and different molecular sizes, and different inter- and intra-specific diversity dynamics. Last, planktonic microbiomes are highly dynamic and complex in inter- and intraspecific diversity in merely one diel cycle, which point to different temperature preference between species, Microcystis aeruginosa and Anabaena sp. This difference was experimentally confirmed in laboratory. Using a multi-omics approach, our study underscores the importance of diel interaction triad between population abundance, biological functions, and environmental factors in leading to microbiome structural change and blooms.</p>
Project description:As an essential primary producer, cyanobacteria play an important role in the global cycle for both carbon and nitrogen in the ecosystems. Though the influence of nanoplastics on the carbon metabolism of cyanobacteria, especial Microcystis aeruginosa, a dominant species causing cyanobacterial blooms, is well studied, little is known about nanoplastics affecting the nitrogen metabolism.
Project description:Eutrophication can lead to an uncontrollable increase in algal biomass, which has repercussions for the entire microbial and pelagic community. Studies have shown how nutrient enrichment affects microbial species succession, however details regarding the impact on community functionality are rare. Here, we applied a metaproteomic approach to investigate the functional changes to algal and bacterial communities, over time, in oligotrophic and eutrophic conditions, in freshwater microcosms. Samples were taken early during algal and cyanobacterial dominance and later under bacterial dominance. 1048 proteins, from the two treatments and two timepoints, were identified and quantified by their exponentially modified protein abundance index. In oligotrophic conditions, Bacteroidetes express extracellular hydrolases and Ton-B dependent receptors to degrade and transport high molecular weight compounds captured while attached to the phycosphere. Alpha- and Beta-proteobacteria were found to capture different substrates from algal exudate (carbohydrates and amino acids, respectively) suggesting resource partitioning to avoid direct competition. In eutrophic conditions, environmental adaptation proteins from cyanobacteria suggested better resilience compared to algae in a low carbon nutrient enriched environment. This study provides insight into differences in functional microbial processes between oligo- and eutrophic conditions at different timepoints and highlights how primary producers control bacterial resources in freshwater environments.