Type-specific quantification of particulate methane monooxygenase gene of methane-oxidizing bacteria at the oxic-anoxic interface of a surface paddy soil by digital PCR

Environ Microbiol Rep. 2023 Oct;15(5):392-403. doi: 10.1111/1758-2229.13155. Epub 2023 Apr 20.


Aerobic methane-oxidizing bacteria (MOB) play an important role in mitigating methane emissions from paddy fields. In this study, we developed a differential quantification method for the copy number of pmoA genes of type Ia, Ib, and IIa MOB in paddy field soil using chip-based digital PCR. Three probes specific to the pmoA of type Ia, Ib, and IIa MOB worked well in digital PCR quantification when genomic DNA of MOB isolates and PCR-amplified DNA fragments of pmoA were examined as templates. When pmoA genes in the surface soil layer of a flooded paddy were quantified by digital PCR, the copy numbers of type Ia, Ib, and IIa MOB were 105 -106 , 105 -106 , and 107 copies g-1 dry soil, respectively, with the highest values in the top 0-2-mm soil layer. Especially, the copy numbers of type Ia and Ib MOB increased by 240% and 380% at the top layer after soil flooding, suggesting that the soil circumstances at the oxic-anoxic interfaces were more preferential for growth of type I MOB than type II MOB. Thus, type I MOB likely play an important role in the methane consumption at the surface paddy soil.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Methane
  • Methylococcaceae* / genetics
  • Oxidation-Reduction
  • Polymerase Chain Reaction
  • Soil


  • methane monooxygenase
  • Soil
  • Methane