Ammonium promoting methane oxidation by stimulating the Type Ia methane-oxidizing bacteria in tidal flat sediments of the Yangtze River estuary.

Abstract Estuary and coastal environments have essential ecosystem functions in greenhouse gas sinks and removal of nitrogen pollution. Methane-oxidizing bacteria (MOB) and ammonia-oxidizing bacteria (AOB) communities play critical functions in the estuary's tidal flat sediments. Therefore, the effects of ammonium on MOB communities and methane on AOB communities need to be further explained. In this study, microcosm incubations with different contents of ammonium or methane were conducted for a relatively short (24 h) or long (28 days) period with tidal flat sediments from the Yangtze River estuary. Subsequently, the tagged highly degenerate primer PCR and DNA-based stable isotope probing method were employed to demonstrate the effects on MOB and AOB populations. The results indicated that the methane consumption was enhanced with ammonium supplements within 24 h of incubation. Supplement of 2 μmol/g d.w.s (μmol per gram dry weight soil) NH4+ increased the amount of MOB and its proportion to the total bacteria (p