Aerobic and nitrite-dependent methane-oxidizing microorganisms in sediments of freshwater lakes on the Yunnan Plateau

Applied Microbiology and Biotechnology

Yong Liu & Jingxu Zhang & Lei Zhao & Yuzhao Li & Yuyin Yang & Shuguang Xie

Abstract: Both aerobic methane-oxidizing bacteria (MOB) and nitrite-dependent anaerobic methane oxidation (n-damo) bacteria can play an important role in mitigating the methane emission produced in anoxic sediment layers to the atmo- sphere. However, the environmental factors regulating the distribution of these methane-oxidizing microorganisms in lacustrine ecosystems remain essentially unclear. The present study investigated the distribution of aerobic MOB and ndamo bacteria in sediments of various freshwater lakes on the Yunnan Plateau (China). Quantitative PCR assay and clone library analysis illustrated the spatial variations in the abundances and structures of aerobicMOBand n-damo bacterial communities. Type I MOB (Methylosoma and Methylobacter) and type II MOB (Methylocystis) were detected, while type I MOB was more abundant than type II MOB. Lake sediments n- damo bacterial communities were composed of novel Methylomirabilis oxyfera-like pmoA genes. Lake sediments in the same geographic region could share a relatively similar aerobic MOB community structure. Moreover, Pearson’s corre- lation analysis indicated that n-damo pmoA gene diversity showed a positive correlation with the ratio of organic matter to total nitrogen in lake sediment.

Keywords: Methane-oxidizing bacteria; Nitrite-dependent anaerobicmethane oxidation; High latitude; Lake; Sediment