Taxonomic and Functional Differences between Microbial Communities in Qinghai Lake and Its Input Streams

Abstract

Understanding microbial communities in terms of taxon and function is essential to decipher the biogeochemical cycling in aquatic ecosystems. Lakes and their input streams are highly linked. However, the differences between microbial assemblages in streams and lakes are still unclear. In this study, we conducted an intensive field sampling of microbial communities from lake water and stream biofilms in the Qinghai Lake watershed, the largest lake in China. We determined bacterial communities using high-throughput 16S rRNA gene sequencing and predicted functional profiles using PICRUSt to determine the taxonomic and functional differences between microbial communities in stream biofilms and lake water. The results showed that stream biofilms and lake water harbored distinct microbial communities. The microbial communities were different taxonomically and functionally between stream and lake. Moreover, streams biofilms had a microbial network with higher connectivity and modularity than lake water. Functional beta diversity was strongly correlated with taxonomic beta diversity in both the stream and lake microbial communities. Lake microbial assemblages displayed greater predicted metabolic potentials of many metabolism pathways while the microbial assemblages in stream biofilms were more abundant in xenobiotic biodegradation and metabolism and lipid metabolism. Furthermore, lake microbial assemblages had stronger predicted metabolic potentials in amino acid metabolism, carbon fixation, and photosynthesis while stream microbial assemblages were higher in carbohydrate metabolism, oxidative phosphorylation, and nitrogen metabolism. This study adds to our knowledge of stream-lake linkages from the functional and taxonomic composition of microbial assemblages.

Impact of Nutrient and Stoichiometry Gradients on Microbial Assemblages in Erhai Lake and Its Input Streams

“…However, according to similarity analyses of the bacterial communities, there was obvious spatial heterogeneity in the bacterial community structure between the lake and the streams, reflecting significant changes in relative abundances of various taxa. These results are consistent with previous studies of stream bacterial communities in connected lake and stream ecosystems [16,35]. The dramatic changes in bacterial community composition between the lake and the streams indicates significant variations in ecological function and nutrient metabolism [36].…”

“…Ecosystem metabolism is directly influenced by the relative balance of external loading of nutrients and dissolved organic carbon in lakes [13]. Stream ecosystems are primary receivers of nutrients and organic matter that export from terrestrial ecosystems through transport and storage of water, nutrients, and energy [14][15][16], and these nutrients and organic matter are transported by streams into lakes and marine environments [13]. In stream ecosystems, microbial assemblages primarily occur in the form of benthic biofilms [17], which play an important role in biogeochemical cycling, being responsible for organic matter mineralization, nutrient uptake, and transformation of contaminants [18].…”

“…However, most studies of bacterial communities have focused only on single environment types, such as lakes or streams. Comparative information on the comparison of bacterial assemblages and their driving forces in lakes and input streams is still limited [16].…”

Aquatic microbial community is partially functionally redundant: insights from an in situ reciprocal transplant experiment

“…Understanding the diversity and role of microbial communities is important because microbes are ubiquitous (Hug LA et al, 2016) and drive ecosystem processes by governing biogeochemical cycles ( Ren Z et al, 2017; Graham BE et al, 2016; Falkowski PG et al, 2008). In recent years, researchers have studied community compositions and functions and attempted to understand the community function relationship in different ecosystems ranging from oceans ( Tringe S et al, 2005; Louca S et al, 2016; Galand PE et al, 2018 ) to freshwater ecosystems ( Gasol MJ, 2002; Peter H et al, 2011; Langenheder S et al, 2005 ), soil ( Griffiths BS et al, 2003; Bahram M et al, 2018 ), plants ( Reich PB et al, 2012; Louca S et al, 2017 ), and the human gut ( Turnbaugh PJ et al, 2009; Moya A and Ferrer M, 2016 ).…”

“…Understanding the diversity and role of microbial communities is important because microbes are ubiquitous [1] and drive ecosystem processes by governing biogeochemical cycles [2-4]. In recent years, researchers have studied community compositions and functions and attempted to understand the community function relationship in different ecosystems ranging from oceans [5-7] to freshwater ecosystems [8-10], soil [11, 12], plants [13, 14], and the human gut [15, 16].…”