Disentangling the lifestyle of bacterial communities in tropical soda lakes

Abstract

Microbial lifestyles may reveal niche-specific signatures and can contribute to detecting the effects of abiotic fluctuations on biogeochemical cycles. Microorganisms make a tradeoff between optimizing nutrient uptake, improving biomass yield, and overcoming environmental changes according to environmental hostility. Soda lakes are natural environments rich in carbonate and bicarbonate water, resulting in elevated pH and salinities that frequently approach saturation. We hypothesized that during the dry period (elevated pH and salinity), microorganisms try to overcome this harshness by allocating energy to the cellular maintenance process. As these environmental conditions improve during the wet period, microorganisms will begin to invest in nutrient uptake. To test this hypothesis, we evaluated four soda lakes in two different seasons by applying metagenomics combined with flow cytometry (estimate heterotrophic bacterial biomass). The natural occurrence of cyanobacterial blooms in some lakes is the main driver of carbon. These primary producers provide organic carbon that supports heterotrophic bacterial growth and, consequently, a high biomass yield. Under harsh conditions (dry season), cyanobacteria invest in nutrient uptake mechanisms, whereas heterotrophic bacteria allocate energy to survive at the expense of biomass yield. Lakes without cyanobacteria blooms invest in nutrient uptake independent of environmental hostility. This study clarifies the microbial tradeoffs in hostile environments and the impact of this choice on carbon and energy flux in tropical alkaline lakes.

Contrasting Response of Microeukaryotic and Bacterial Communities to the Interplay of Seasonality and Stochastic Events in Shallow Soda Lakes

“…Soda lakes and pans are characterised by abundant phytoplankton 13,40 zooplankton 41,42 that feeds large amounts of migratory birds 43,44 , while fish are typically absent 45 . Studies describing the planktonic microbiome of soda pans in the Carpathian Basin [45][46][47][48] , Canada 49 , Brazilia 50 , China 51 and East Africa 52 have identified unique bacterial and eukaryotic communities. The seasonal changes of the composition 46,47 and function 53 of bacterial communities of soda lakes and pans have also been described before, but the impact of seasonality on the interactions of bacterial and microeukaryotic species remains to be explored.…”