[Objective] Methane-oxidizing bacteria (MOB) are crucial indicators in the microbial exploration of oil and gas reservoirs, while their diversity and distribution are influenced by geographical location and environmental factors. This study aims to explore the effects of environmental variations on the abundance and distribution of MOB in the soil samples collected from seven representative areas in typical oil and gas reservoirs. [Methods] Soil samples were subjected to real-time fluorescence quantitative PCR (qPCR) forpmoA and sequencing of bacterial 16S rRNA gene andpmoA. The abundance of MOB was compared among different samples, on the basis of which the impacts of environmental factors on the distribution of MOB were analyzed. [Results] The highest water content (approximately 22.8%) was detected in the samples from the Jianghan Basin. The average content of nitrate nitrogen was highest in the Yubei oil field, reaching approximately 31.96 μg/g. The Chunguang oil field showcased the highest concentrations of SO42− (6 425.0 mg/g) and Cl− (1 617.0 mg/g). The qPCR results revealed that thepmoA in MOB accounted for only 0.77% of that in total soil bacteria, indicating the low absolute abundance of MOB in the soil. The 16S rRNA gene sequencing identified three type Ⅰ MOB genera (Methylosarcina,Methylocaldum, andMethylococcus) and one type Ⅱ MOB genera (Methylocystis). However, the dominant genera in the MOB had extremely low relative abundance, with the maximum of 0.124%. Sequencing ofpmoA revealed thatMethylocystis andMethylosinus, two genera of type Ⅱ MOB, were dominant. The absolute abundance of MOB showed significant correlations with ammonium nitrogen, pH, particle size, SO42−, and Cl−. The relative abundance of MOB had significant correlations only with particle size, total nitrogen, total phosphorus, and metal ions (Al, Fe, K, Ca, Mg, Mn, Zn, and Cu). The discriminant correlation analysis (DCA) indicated that soil moisture, pH, soil particles<2 μm, total nitrogen, and Ca2+ significantly influenced the composition of the functional genepmoA in MOB. [Conclusion] This study analyzed the absolute and relative abundance of MOB in soil samples from seven typical oil and gas reservoirs. The MOB abundance showed significant differences depending on the measurement method used. The 16S rRNA gene sequencing fails to comprehensively reflect the community structure of MOB in the soil samples. Different geographical locations showed variations in MOB communities, and no specific indicator communities were detected for oil and gas reservoirs or background sites on a national scale. The correlation analysis between environmental factors and MOB revealed that the environmental factors had different effects on the absolute and relative abundance of MOB.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |