Impact of increasing temperature on the taxonomic and metabolic structure of bacterial communities in a global warming context

Climate change is one of the most severe threats for ecosystems worldwide. Lakes can be studied as indicators of climate change. The prokaryotic compartment of lakes is affected by climate change, and the metabolic processes of prokaryotes could both attenuate or exacerbate the negative impacts of climate change on the ecosystem. However, in contrast to studies on the impact of global warming on eukaryotes, prokaryotes have been rarely studied in the context of climate change. In our study, we tested the impact of short-term temperature increases on taxonomic and physiological bacterial diversity and their relationships. We conducted an experiment with different temperature treatments using mesocosms filled with lake water from the same water reservoir. We monitored physicochemical parameters for 2 wk and examined taxonomic diversity using Illumina next-generation sequencing and metabolic diversity using 31 carbon sources by the Biolog EcoPlate® method. We showed that a continuous increase in water temperature for 14 d significantly affected the taxonomic structure of bacteria that inhabit lake water. Even when the water temperature was within the temperate zone of 26 to 29°C, a slight increase in biodiversity in the first few days was observed, and after 14 d, the change in temperature drastically decreased biodiversity. In the case of physiological diversity, the differences were relatively small. Similarly, we did not find a statistically significant correlation between the taxonomic and physiological diversity of lake bacteria in the context of climate change. This may indicate redundancy of aquatic bacteria communities.