Resource niche overlap promotes stability of bacterial community metabolism in experimental microcosms

Abstract

Decomposition of organic matter is an important ecosystem process governed in part by bacteria. The process of decomposition is expected to benefit from interspecific bacterial interactions such as resource partitioning and facilitation. However, the relative importance of resource niche breadth (metabolic diversity) and resource niche overlap (functional redundancy) on decomposition and the temporal stability of ecosystem processes received little scientific attention. Therefore, this study aims to evaluate the effect of an increase in bacterial community resemblance on both decomposition and the stability of bacterial metabolism in aquatic sediments. To this end, we performed laboratory microcosm experiments in which we examined the influence of bacterial consortia differing in number and composition of species on bacterial activity (Electron Transport System Activity, ETSA), dissolved organic carbon production and wavelet transformed measurements of redox potential (Eh). Single substrate affinities of the individual bacterial species were determined in order to calculate the metabolic diversity of the microbial community. Results presented here indicate that bacterial activity and organic matter decomposition increase with widening of the resource niche breadth, and that metabolic stability increases with increasing overlap in bacterial resource niches, hinting that resource niche overlap can promote the stability of bacterial community metabolism.

Coupling Spatiotemporal Community Assembly Processes to Changes in Microbial Metabolism

“…Importantly, changes in community composition in our system are associated with a seasonal increase in microbial metabolism, consistent with work in both micro- and macroecology demonstrating that productivity increases with niche diversification (Hooper et al, 2005; Cardinale et al, 2007; Cardinale, 2011; Gravel et al, 2011; Hunting et al, 2015). Specifically, we observed positive correlations between Raz:ATP and Thaumarchaeota abundance coincident with negative correlations between Raz:ATP and Betaproteobacteria ( Figure 5D ).…”

Significance of sunlight for organic matter degradation in aquatic systems

“…recalcitrant substrates nor specific substrates typical of the plant leaves used in this study. It is thus impossible to directly relate the carbon substrates utilization to actual microbial density and community structure, as well as their relative metabolic activity and how they would function under natural conditions, yet the number of utilized substrates offers a proxy of the metabolic or functional diversity of a microbial community (Hunting et al 2013b, Zhai et al 2016, or the resource breadth utilized by the bacterial community (Hunting et al 2015(Hunting et al , 2017. Plates were incubated for 96 h at 18°C and absorbance was measured at 590 nm using a BIO-RAD SmartSpec ™ Plus spectrophotometer.…”

Contribution Evenness: A functional redundancy metric sensitive to trait stability in microbial communities

“…The level of functional redundancy in a microbiome has been shown to affect ecosystem function in diverse environments. For instance, high functional redundancy in freshwater sediments resulted in stabilized porewater redox conditions (7). In surface seawater, a metagenomic analysis of glycosyl hydrolase genes demonstrated a complex successional pattern in heterotrophs which correlated with coastal phytoplankton bloom life cycles and influenced ecosystem organic carbon processing (8).…”

“…One common method is to compare changes in ecosystem function to changes in community composition. Stability in ecosystem function with increasing microbial diversity is often considered an empirical indication of functional redundancy (7, 16, 17). A complimentary approach is to use ‘omics data as indicators of traits (18, 19).…”