Comparison of methanotrophic community and methane oxidation between rhizospheric and non-rhizospheric soils

Using particulate methane monooxygenase (pMMO) encoding gene, pmoA-based terminal-restrict fragment length polymorphism (T-RFLP), the methanotrophic communities between rhizospheric soils (RSs) and non-rhizospheric soil (NRSs) of landfill cover (LC), riparian wetland (RW) and rice paddy (RP) were compared before and after pre-incubation of 90 days. The ultimate potential ofmethane oxidation rate (UPMOR) and gene copy number of pmoA were evaluated in the soil samples after pre-incubation. Compared to the methanotrophic community in the soil samples before pre-incubation, type II methanotrophs, the Methylocystis- Methylosinus group, was mostly increased after pre-incubation, regardless of the soil type. The UPMOR (11.82 ± 0.27 μmol- CH4· g ^-1 _soil-DW·h ^-1) in the LC-RS was significantly higher than that (9.57 ± 0.14 μmol-CH4· g ^-1 _soil-DW·h ^-1) in the LC-NRS. However, no significant difference was found between RSs and NRSs in the RW (15.28 ± 0.91 and 13.23 ± 0.69 μmol-CH4· g ^-1 _soil-DW·h ^-1, respectively) and RP (13.81 ± 1.04 and 12.81 ± 2.40 μmol-CH4· g ^-1 _soil-DW·h ^-1, respectively) soils. There was no significantly difference in the gene copy numbers of pmoA in the RSs compared with those in the NRSs at all of the sampling sites. This study provides basic metagenomic information about both rhizospheric and nonrhizospheric methanotrophs, which will be helpful in developing a better strategy of biological methane removal from both natural and anthropogenic major methane sources.