Adaptation of methane-oxidizing bacteria to environmental changes: implications for coastal methane dynamics

Abstract

Global warming induces alterations in ocean temperature regimes, as well as in precipitation patterns. This leads to shifts in water column properties, which will increasingly impact coastal ecosystems. These changes may have profound implications for microbial communities such as methane-oxidizing bacteria (MOBs), which play a critical role in regulating methane fluxes and ecosystem dynamics. In this study, we investigate the resilience and adaptability of aerobic MOBs in response to changing environmental conditions. Microcosm incubations with waters from the North Sea and the Wadden Sea collected across different seasons and adjusted for methane availability, temperature, and salinity were used to assess how these factors shape MOB community structure and functional capacity. Our results reveal an increase in the relative abundance of MOBs to up to 57 % in experiments with elevated methane concentrations, highlighting the primary role of methane availability in MOB community development. Temperature and salinity variations, on the other hand, exerted lesser effects on MOB composition and relative abundance. A strong effect on MOB community development was furthermore caused by the origin of the inoculum (location and season). Our results thus suggest a functional redundancy in the variable pools of microbial inocula, enabling multiple MOB clades to cope with drastic changes in environmental parameters. The adaptability of MOB communities is key to understanding their role in mitigating methane emissions from coastal regions in a future ocean with potentially elevated methane and temperature and variable salinity levels.