Community structure and methylation of microbes in an artificially forced sediment core

Epigenetic modifications, such as DNA methylation, may be used in prokaryotes for the adaptation of microbes to external environmental changes. In this study, we examined the microbial community structure, recovered the genomes of the dominant microbes, and tracked methylation in several dominant microbes in a 23-cm artificial sediment core formed in a settling tank that mimics the sediment formation process. Our results indicated that the prokaryotic communities only showed minor variations with depth and were dominated by bacteria (especially taxa of Deltaproteobacteria, Gammaproteobacteria, and Bacteroidota), while archaea (dominated by Bathyarchaeia) accounted for <5% of the total communities throughout the core. We detected methylation by analyzing metagenome sequencing data of methyl-specific enzyme-digested and undigested DNA. We recovered 72 high- or medium-quality metagenome-assembled genomes for the dominant taxa, for 7 of which we detected distinct downcore methylation patterns. This work highlights the diverse processes of epigenetic modification in response to the sediment burial process, which may have a long-term impact on the overall community fitness in the evolving energy-limited conditions in marine sediments.IMPORTANCEThis work reports changes in the epigenetic profiles of microbes buried in a sediment column formed under a controlled, artificially created environment. This approach removes confounding variables of bioturbation and changes in sediment flux. We also use an approach that is accessible for low amounts of DNA to determine methylation status.