Spatiotemporal dynamics of bacterial community composition in large shallow eutrophic Lake Taihu: High overlap between free‐living and particle‐attached assemblages

Abstract

In eutrophic lakes, heterotrophic bacteria are closely associated with algal detritus and play a crucial role in nutrient cycling. However, the seasonal and spatial dynamics of free-living (FL) and particle-attached (PA) bacteria and the environmental factors shaping this relationship remain poorly understood. To address this issue, we explored the spatiotemporal patterns of bacterial community composition (BCC) in Lake Taihu, China, using terminal restriction fragment length polymorphism (T-RFLP) and 454-tag pyrosequencing of 16S rRNA gene. We generated a total of 218,027 high quality non-cyanobacterial sequence reads that resulted in 4940 OTUs (97% cutoff), with Actinobacteria, b-and a-proteobacteria being the predominant taxa. Although PA communities contained significantly higher alpha-diversity than FL ones, we found that 59% of OTUs, that accounted for 96% of the total reads, were shared by both communities. The high degree of overlap between FL and PA communities indicates a high rate of dispersal potential, highlighting an underestimated connectivity and potentially similar ecological role for these two components. Distinct seasonal trends were recorded in both FL and PA communities, while spatial differences in BCC were small. In addition, both FL and PA bacterial communities exhibited similar patterns and synchrony, correlated to water temperature, nitrate and total suspended solids (TSS). Accordingly, the effects of eutrophication and hydrodynamics on the phylogenetic overlap and diversity between FL and PA communities were discussed.

Large buoyant particles dominated by cyanobacterial colonies harbor distinct bacterial communities from small suspended particles and free‐living bacteria in the water column

“…In addition, dbRDA revealed that NO 3 − significantly correlated with the distribution pattern of bacterial community in all three habitats. The effect of NO 3 − on bacterial community structure was also shown in previous studies of Lake Taihu (Tang et al., ), Lake Tanganyika (De Wever et al., ), and the mesotrophic Lake Tiefwaren (Roesel, Allgaier, & Grossart, ). NO 3 − may directly or indirectly affect bacterial proliferation through cyanobacterial abundance and composition, which are greatly affected by nutrient concentration (Xu, Paerl, Qin, Zhu, & Gaoa, ).…”

“…Many studies compared particle-attached bacterial communities and free-living bacterial communities, but controversial observations were also drawn. Some studies observed that particle-attached bacterial communities are phylogenetically distinct from free-living bacterial communities (Allgaier & Grossart, 2006;Zhao et al, 2017), whereas some studies observed that these two communities are similar and may exchange in freshwater mesocosms (Riemann & Winding, 2001;Tang et al, 2015Tang et al, , 2017Worm, Gustavson, Garde, Borch, & Sondergaard, 2001). However, this study further concluded that particles collected during different season may be a major reason for these controversial observations.…”

“…Many works have focused on bacterial communities associated with cyanobacterial blooms (Berg et al, 2009;Berry et al, 2017;Dziallas & Grossart, 2011;Eiler & Bertilsson, 2004;Niu et al, 2011;Tang et al, 2010;Woodhouse et al, 2016). Some works revealed the transition of particle-attached bacteria to free-living bacteria during a 4-month investigation (Tang et al, 2015(Tang et al, , 2017, and others investigated the difference between particle-attached bacteria and free-living bacteria (Zhao et al, 2017). The bacteria attached to medium-and small-sized cyanobacterial aggregates during August and September were clustered, whereas large-and medium-sized aggregate communities in the October sample were grouped together and appeared distinct from the small-sized aggregate community (Cai, Jiang, Krumholz, & Yang, 2014;Cai, Yan, Wang, Krumholz, & Jiang, 2013).…”

Bacteria and microeukaryotes are differentially segregated in sympatric wastewater microhabitats

“…In the ocean and in lakes, planktonic and floc bacterial communities differ, but they still share many taxa (Biži c-Ionescu et al, 2015;Tang et al, 2017;Zhao et al, 2017). Segregation leading to spatial differentiation may occur at deep phylogenetic levels (Tang et al, 2017) with segregated populations partitioning resources and sustaining different trophic networks (Hunt et al, 2008;Xu et al, 2018). A possible mechanism driving the process of differentiation between closely related taxa in flocs and liquor is the modification of cell-surface structures resulting in changes in hydrophobicity, a property known to increase flocculation (Wilén et al, 2003).…”

“…In other aquatic environments (the ocean, oligotrophic and eutrophic lakes), it has been shown that the structures of particle-associated and free-living planktonic bacterial communities differ (Hunt et al, 2008;Biži c-Ionescu et al, 2015;Tang et al, 2017). In WWTPs however, despite significant differences in the physicochemical characteristics between flocs and liquor, such processes have hitherto not been investigated.…”