Tracking of the activity of individual bacteria in temperate forest soils shows guild-specific responses to seasonality

摘要

Bacteria belong to the key players in the carbon cycling in forest soils and thus affect the global C balance. Our understanding of bacterial contribution to ecosystem processes relies on the analysis of whole communities. Here we combined strain isolation, genome sequencing and metatranscriptomics to analyse the activity of individual bacterial species in the topsoil of a temperate coniferous forest. Our results show that transcription profiles in litter and soil differ, indicating that bacterial activity is shaped by their habitat. Importantly, transcript pools also significant differ between summer when primary producers are active and winter. We show that Acidobacteria and Bacteroidetes with high metabolic capacity for polysaccharide decomposition in their genomes actively transcribe corresponding genes in situ. The rate of the transcription of ribosomal proteins, a proxy of growth, seasonally differs between these "decomposer" taxa and other "opportunistic" bacteria. While the former grow at similar rates in summer and winter, the latter grow much faster in summer when labile C, delivered by plant roots, is available. This paper demonstrates differences in activity of bacterial guilds as well as the importance of environmental drivers for the activity of individual bacteria.