US EPA

2488968 

Journal Article 

Competitive interactions between methane- and ammonia-oxidizing bacteria modulate carbon and nitrogen cycling in paddy soil 

Zheng, Y; Huang, R; Wang, BZ; Bodelier, PLE; Jia, ZJ 

2014 

Yes 

Biogeosciences
ISSN: 1726-4170
EISSN: 1726-4189 

11 

12 

3353-3368 

10.5194/bg-11-3353-2014 

WOS:000338761200018 

Pure culture studies have demonstrated that methanotrophs and ammonia oxidizers can both carry out the oxidation of methane and ammonia. However, the expected interactions resulting from these similarities are poorly understood, especially in complex, natural environments. Using DNA-based stable isotope probing and pyrosequencing of 16S rRNA and functional genes, we report on bio-geochemical and molecular evidence for growth stimulation of methanotrophic communities by ammonium fertilization, and that methane modulates nitrogen cycling by competitive inhibition of nitrifying communities in a rice paddy soil. Pair-wise comparison between microcosms amended with CH4, CH4+Urea, and Urea indicated that urea fertilization stimulated methane oxidation activity 6-fold during a 19-day incubation period, while ammonia oxidation activity was significantly suppressed in the presence of CH4. Pyrosequencing of the total 16S rRNA genes revealed that urea amendment resulted in rapid growth of Methylosarcina-like MOB, and nitrifying communities appeared to be partially inhibited by methane. High-throughput sequencing of the C-13-labeled DNA further revealed that methane amendment resulted in clear growth of Methylosarcina-related MOB while methane plus urea led to an equal increase in Methylosarcina and Methylobacter-related type Ia MOB, indicating the differential growth requirements of representatives of these genera. An increase in C-13 assimilation by microorganisms related to methanol oxidizers clearly indicated carbon transfer from methane oxidation to other soil microbes, which was enhanced by urea addition. The active growth of type Ia methanotrops was significantly stimulated by urea amendment, and the pronounced growth of methanol-oxidizing bacteria occurred in CH4-treated microcosms only upon urea amendment. Methane addition partially inhibited the growth of Nitrosospira and Nitrosomonas in urea-amended microcosms, as well as growth of nitrite-oxidizing bacteria. These results suggest that type I methanotrophs can outcompete type II methane oxidizers in nitrogen-rich environments, rendering the interactions among methane and ammonia oxidizers more complicated than previously appreciated.