深海热液喷口金属硫化物中甲烷菌的多样性研究

Studies on the biodiversity of methanogens from hydrothermal vent chimney

对两个来自太平洋洋脊胡安·德富卡的两个热液烟囱的金属硫化物4136．2和4148-B1进行甲烷菌甲基辅酶M还原酶的编码基因mcrA的序列扩增，构建克隆文库并进行分子进化分析。结果表明在这个甲烷富集的热液喷口周围含有丰富的甲烷产生菌，没有任何甲烷氧化菌存在。两个硫化物样品的甲烷产生菌种类完全不同。在4136—2硫化物中的甲烷产生茵郝与热液口的高温环境有关系，主要属于甲烷球菌目的甲烷暖球菌（Methanocaldococcus），少部分属于甲烷火茵目甲烷嗜高热菌属的坎氏甲烷嗜高热菌（Methanopyruskandleri）。与这两个属的可分离菌株的氨基酸同源性为89％-97％，核苷酸同源性高达92％～100％。4148-B1硫化物中发现的一类疑似甲基辅酶M还原酶的编码序列，它们与已知的甲烷菌mcrA序列核苷酸同源性为69％～72％，氨基酸同源性仅为43％～47％。这可能是由于4148．B1来自于正在喷发的超高温热液喷口相关。由于与已发表的甲烷菌克隆子或菌株同源性较低，有可能是热液口特有的以前未发现的甲烷茵。

The chimney sulfides （named 4136-2 and 4148-B1） obtained from Juan de Fuca Ridge were used as samples, aiming at mcrA gene amplification, clone library construction and phylogenetic tree analysis. The results showed that there were only CH4 production microbes but no CH4 oxidation microbes in the samples and the species in the two sulfides were different. The methanogen from 4136-2 sulfide rock were linked to a high temperature en- vironment. These methanogen belong to Methanocaldococcus and Methanopyrus kandleri. The similarities of pro- tein sequences between 4136-2 clones and isolated Methanocaldococcus and Methanopyrus kandleri strains were from 89% to 97%, and The similarities of mucleotide sequences between 4136-2 clones and isolated Methanocal- dococcus and Methanopyrus kandleri strains were from 92% to 100%. The mcrA sequences from 4148-B1 sulfide rock had low identities with sequences deposited in GenBank. The similarities of mucleotide sequences identities of 4148-B1 clones and published mcrA sequences were form 69% to 72%, and the similarities of protein sequences were form 43% to 37%. This also linked to its super high temperature environment and may suggest there were un-discovered methanogen living in the vent.