Thermal stratification is a key physical process influencing the life cycle of reservoirs, forming vertical temperature gradients that limit the mixing of oxygen and nutrients, especially phosphorus.   With global warming intensifying stratification, surface waters face phosphorus depletion, which is essential for microbial metabolism.   Some heterotrophic bacteria, such as those possessing the phosphonate-degrading (phn) gene cluster, can adapt to phosphorus-limited environments by utilizing phosphonates as an alternative phosphorus source.  In marine systems, methylphosphonate degradation has been linked to methane release, but its role in freshwater ecosystems remains less understood. In this study, we isolated Variovorax xiamenensis sp. nov., a novel phosphonate-utilizing strain W6, from a seasonally stratified reservoir.   Strain W6 uses phosphonates as its sole phosphorus source under P-limiting conditions and releases methane in the presence of methylphosphonate.   RNA-seq analysis was performed to investigate its cellular response and potential ecological implications in the reservoir environment.

Phosphonate utilization; Freshwater bacteria; Oxic methane production