Bacterial lag phase shortening is triggered by methyl groups

Short lag times are beneficial for heterotrophic bacteria that compete for resources in environments with fluctuating organic carbon levels. We found that the marine model bacterium Phaeobacter inhibens achieves shorter lag times in the presence of nano-to micromolar concentrations of N-or S-methylated compounds, which are abundantly produced by microalgae. To understand the underlying mechanism, we studied algal-bacterial co-cultures and bacterial pure cultures during their lag phase using transcriptomics analyses, 13C-labeled metabolomics, gene knock-out experiments and enzymatic characterizations. Our findings highlight methyl group synthesis as a bottleneck during the bacterial lag phase, which can be overcome by assimilating methyl groups from external sources. Our study reveals a fundamental aspect of the bacterial lag phase, emphasizing the importance of studying bacterial physiology within an ecological framework, particularly in the context of microbial interactions.