海岸带沉积物环境中甲烷代谢菌的富集培养及混合菌群分析

Enrichment cultivation of methane metabolic bacteria in the environment of sediments from the coastal zones and analysis of mixed bacteria communities

结合Hungate无氧分离技术,对海岸带沉积物中甲烷代谢菌进行了富集培养,分别为珠江口的甲烷产生菌和九龙江口的甲烷氧化菌及其他甲基氧化菌.其研究结果表明:在珠江口淇澳岛海岸带沉积物中,甲烷八叠球菌属(Methanosarcina)为优势菌株,分布于沉积物的上、中、下3个层位,并发现了部分序列与不可培养的泉古菌门(Crenarchaeota)的杂色泉古菌(miscellaneous crenarchaeotic group,MCG)的相似度为90%～99%.在九龙江口的海岸带沉积物环境中,噬甲基菌属(Methylophaga)为优势菌群,在富集产物菌群多样性中占60%～99%;还有一些相似度较低(为95%～97%)的菌群,为潜在的新种.

Methane （ CH4 ） is one of the main ＂ greenhouse gases＂ responsible for global warming. Most methane in the atmosphere is the result of the interaction between Methanogens and Methanotrophs. Therefore, it is of great significance for both energy and environment to research Methanogens and Methanotrophs. In this study, enrichment and biodiversity analyses were conducted on bacteria related to methane metabolism from the coast- al zone sediments. The Methanogens from Qi＇ ao Island in the Pearl River Estuary, China and the Methanotro- phs and other methyl-oxidizing bacteria from the Jiulongjiang River Estuary, China were cultivated. The main experimental methods included the Hungate anaerobic technique for enrichment and isolation as well as a mo- lecular biological technique for biodiversity analysis was made on the enrichment products. The current study indicated that Methanosarcina was the predominant genus identified throughout the three layers of sediments found in the seashore area of Qi＇ ao Island in Pearl River Estuary. These bacteria could utilize propionate and lactate as substrates in addition to utilizing methanol, H2/CO2, mono-methylamine（MMA） , double-methyla- mine（DMA）, trimethylamine （TMA）, as previously reported. The uncultured miscellaneous crenarchaeotic group （MCG） of Crenarchaeota was identified in the lower layer of the sediments that used lactic acid as a substrate. To our knowledge, this is the first report that the uncultured MCG was obtained through an enrich- ment method. Meanwhile, for Jiulongjiang River Estuary samples, Methylophaga was the predominant genus, accounting for 60% -99% of the total enriched bacteria. Further, some microflora of low similarities could be new species that warrant further investigation for their potential industrial applications. This is the first report of the analysis of the bacteria related to methane metabolism from coastal zone sediments using an enrichment method to explore further studies on the relationship between the bacteria related to methane metabolism andthe ecological environment of the coastal zone.