Spatial Patterns of Methane Oxidation and Methanotrophic Diversity in Landfill Cover Soils of Southern China

Abstract

Aerobic CH4 oxidation is an important CH4 sink in landfills. To investigate the distribution and community diversity of methanotrophs and link with soil characteristics and operational parameters (e.g., concentrations of O2, CH4), cover soil samples were collected at different locations and depths from the Mengzi semi-aerobic landfill (SAL) in Yunnan Province of southern China. Specific PCR followed by denaturing gradient gel electrophoresis and realtime PCR were used to examine methanotrophs in the landfill cover soils. The results showed that different locations did harbor distinct methanotroph communities. Methanotrophs were more abundant in areas near the venting pipes because of the higher O2 concentrations. The depth of 20-25 cm, where the ratio of the CH4 to O2 was within the range from 1.3 to 8.6, was more conducive to the growth of CH4-oxidizing bacteria. Type II methanotrophs dominated in all samples compared with Type I methanotrophs, as evidenced by the high ratio of Type II to Type I methanotrophic copy numbers (from 1.76 to 11.60). The total copy numbers of methanotrophs detected were similar to other ecosystems, although the CH4 concentration was much higher in SAL cover soil. Methylobacter and Methylocystis were the most abundant Type I and Type II methanotrophs genera, respectively, in the Mengzi SAL. The results suggested that SALs could provide a special environment with both high concentrations of CH4 and O2 for methanotrophs, especially around the vertical venting pipes.

Potential of Immobilized Whole-Cell Methylocella tundrae as a Biocatalyst for Methanol Production from Methane

“…Biosynthetic methanol production is performed by methanotrophs, which can utilize CH 4 as their sole carbon and energy source [2,41]. Methanotrophs are categorized into three types (I, II, and X) based on their carbon assimilation pathway, cell morphology, membrane arrangement, and 16S rRNA sequences.…”

Methane Emission Reduction and Biological Characteristics of Landfill Cover Soil Amended With Hydrophobic Biochar

“…Methylocaldum and Methylloccus were also classified among them as Type X ( Kalyuzhnaya et al, 2015 ). The dominant MOB in the upper layer of CB and CH were Type Ⅰ Methylobacter , which is the major abundant methanotrophs reported in other studies of landfill cover soil ( Chi et al, 2015 ; Reddy et al, 2019 ). The green fluorescence representing Type I MOB in the upper layer of CH was more and brighter than that of CB ( Figures 5A,B ), and the total abundance of MOB in the upper layer of CH(55.93%) was higher than that of CB(50.80%), which was consistent with changes of the CH 4 removal efficiency in this depth ( Figure 2 ).…”

Effect of soil types and ammonia concentrations on the contribution of ammonia-oxidizing bacteria to CH4 oxidation

“…Although aged refuse and compost have been proven to be highly effective cover materials for mitigating CH 4 emission from landfills (Abichou et al, 2009; He et al, 2012; Zhang et al, 2013, 2015), the CH 4 oxidation rates in these soil types were much lower than that in landfill cover soil. This could be for the following reasons: (a) since landfill cover soils were incubated for a longer period, the pmoA copy number in this soil was 4.8 and 3.1 times higher than those in compost and aged refuse, respectively (Chi et al, 2015; He et al, 2008); (b) due to their high toxicities, the higher NO 3 -N and NH 4 + -N concentrations in the compost and aged refuse may have inhibited the activity of MOB (Dunfield and Knowles, 1995; King and Schnell, 1994; Mochizuki et al, 2012); and (c) CH 4 -oxidizing bacteria and other heterotrophic bacteria compete for the limited O 2 available in aged refuse and compost. Therefore, pretreatment of soils prior to their use as landfill cover with CH 4 could be an effective measure for limiting CH 4 emissions from landfills.…”