Biological and chemical factors driving the temporal distribution of cyanobacteria and heterotrophic bacteria in a eutrophic lake (West Lake, China)

Abstract

Physico-chemical parameters, hydrological conditions, and microbial interactions can affect the growth and persistence of cyanobacteria, but the interacting effects among these bloom-forming factors are still poorly known. This hampers our capacity to predict the occurrence of cyanobacterial bloom accurately. Here, we studied the relationship between temperature, N and P cycles, and the microbial community abundance and diversity at 0.5 m under the surface of West Lake (China) from January 21 to November 20, 2015, in order to better understand the key factors regulating temporal changes in the cyanobacterial community. Using high throughput sequencing of the 16S rRNA gene V3-V4 region, we studied the diversity and abundance of bacteria. In parallel, we measured physico-chemical parameters and followed the abundance of key genes involved in N fixation, denitrification, and nutrient uptake. Multivariate analyses suggest that P concentration and water temperature are the key factors controlling the outbreak of summer cyanobacterial bloom. RT-qPCR analyses of the bacterial community and measurements of the copy number of denitrification-related gene (nirK, nosZ, nirS) show that denitrification potential and denitrifying bacteria relative abundance (Pseudomonas and Bacillus) increased in concert with diazotrophic cyanobacterial genera (Anabaena, Nostoc, Aphanizomenon flos-aquae) and the common bloom-forming non-diazotrophic cyanobacterium genus Microcystis. The present study brings new insights on the complex interplay between physico-chemical parameters, heterotrophic bacterial community composition, nitrogen cycle, and cyanobacteria dominance in a eutrophic lake.

Genome Sequence and Composition of a Tolyporphin-Producing Cyanobacterium-Microbial Community

“…3). Such diversity is consistent with that of other nonaxenic cyanobacteria from different environments (46)(47)(48)(49)(50), where both free and attached bacteria have been associated with cyanobacterial filaments (47,50). Although the explicit identity of bacteria firmly attached in the SEM images (Fig.…”

Deciphering the effects of nitrogen, phosphorus, and temperature on cyanobacterial bloom intensification, diversity, and toxicity in western Lake Erie

“…Free‐living or epiphytic N‐fixing heterotrophic bacteria may play an important role in providing N to these populations (Worm and Søndergaard ; Davis et al ), thereby supporting their persistence under N‐Limited conditions, although there remains a limited understanding of their importance in Lake Erie (Mou et al ). Such bacteria have been found to be imbedded within Microcystis colonies (Song et al ), which may help explain the muted response of Microcystis to N additions compared to Planktothrix . Additionally, it has been proposed that the presence of co‐occurring diazotrophic taxa may help relieve N stress of these populations, as N fixation can “leak” N‐rich amino acids and ammonium (Ohlendieck et al ; Wetzel ).…”

The Composition and Function of Microbiomes Within Microcystis Colonies Are Significantly Different Than Native Bacterial Assemblages in Two North American Lakes

“…Specifically, in both lakes, there was a higher predicted abundance of several genes involved in nitrate reduction and denitrification pathways. While these reactions primarily occur in anoxic environments (Conrad, 1996), these conditions may develop within colonies at night given their enrichment with bacteria and organic carbon (Zhao et al, 2017) and have likewise been associated with cyanobacteria aggregates in several studies (Cai et al, 2013;Qian et al, 2017;Song et al, 2017). Additionally, members of the Nitrosomonadaceae family, which is associated with the nitrification pathway, were found to be enriched in the MCA fraction in both lakes.…”