Variation in abundance and composition of methane-metabolizing microorganisms from the lower Pearl River to the South China Sea

Abstract:

Methane is a significant greenhouse gas, which is regulated by microbial processes in surficial environments. However, the population dynamics of methanogens and methanotrophs in a particular environment has not been well studied. In this project, the variation of methanogens and methanotrophs in the sediment of the Pearl River estuary and coastal South China Sea was examined along a salinity gradient （A:0.8‰; B: 18.1‰; C: 23.9‰: D: 31‰）over a period of one year. Quantitative PCR showed that the variation in archaeal and bacterial 16S rRNA gene abundance at site A in the lower Pearl River (from 3.6×10³ to 2.6×10⁵ copies/L for archaea and from 1.2×10⁵ to 2.6×10⁶ copies/L for bacteria) is larger than that in at site D in the coastal South China Sea (from 3.5×10⁴ to 2.9×10⁵ copies/L for archaea and from 8.8×10⁵ to 3.2×10⁶ copies/L for bacteria). High throughput sequencing showed that methanogens and methanotrophs were abundant in the sediment of lower Pearl River and decreased sharply with the increasing salinity. Our results indicate that active methane metabolism is favored in the freshwater environment.