High-Affinity Methane Oxidation by a Soil Enrichment Culture Containing a Type II Methanotroph
High-Affinity Methane Oxidation by a Soil Enrichment Culture Containing a Type II Methanotroph
复制标题
通过含有 II 型甲烷氧化菌的土壤富集培养物进行高亲和力甲烷氧化
DOI：
10.1128/aem.65.3.1009-1014.1999
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发表时间：
1999
影响因子：
4.4
通讯作者：
R. Conrad
中科院分区：
文献类型：
--
作者：
P. Dunfield;W. Liesack;Thilo Henckel;R. Knowles;R. Conrad
摘要有机土壤中的甲烷营养细菌在甲烷(CH4)体积比为百万分之二百七十五的混合气体中得到了丰富。经过4年的生长和周期性稀释(为初始土壤接种量的1020倍)，获得了一种混合培养物，其对CH4的表观半饱和常数[Km(App)]为56-186 NM(40-132ppmv)。这个数值与土壤本身的测量值相同，比报道的甲烷氧化菌纯培养的数值低约一个数量级。然而，当培养转移到较高的CH4混合比例(1000ppmv，或1%)时，Km(APP)增加。在-lt；275ppmv的甲烷上生长的富集物变性梯度凝胶电泳显示了pmoA的单一基因产物，它编码颗粒甲烷单加氧酶的一个亚单位。这表明只有一种甲烷型微生物存在。该菌是从1%CH4上生长的增菌培养样品中分离出来的，并根据其16S rRNA、pmoA和mxaF基因序列进行了系统发育定位，属于甲壳菌群/甲氧菌群的II型菌株。该菌株与一株Variovorax sp.共培养时，在275ppmv的CH4上生长时，其Km(App)(129~188 nm)与最初的增菌培养相似。这些数据表明，甲烷营养细菌对CH4的亲和力随生长条件的不同而不同，在该土壤中观察到的大气CH4氧化是由与特征物种相似的II型甲烷营养细菌执行的。
ABSTRACT Methanotrophic bacteria in an organic soil were enriched on gaseous mixing ratios of <275 parts per million of volume (ppmv) of methane (CH4). After 4 years of growth and periodic dilution (>1020 times the initial soil inoculum), a mixed culture was obtained which displayed an apparent half-saturation constant [Km(app)] for CH4 of 56 to 186 nM (40 to 132 ppmv). This value was the same as that measured in the soil itself and about 1 order of magnitude lower than reported values for pure cultures of methane oxidizers. However, theKm(app) increased when the culture was transferred to higher mixing ratios of CH4 (1,000 ppmv, or 1%). Denaturing gradient gel electrophoresis of the enrichment grown on <275 ppmv of CH4 revealed a single gene product ofpmoA, which codes for a subunit of particulate methane monooxygenase. This suggested that only one methanotroph species was present. This organism was isolated from a sample of the enrichment culture grown on 1% CH4 and phylogenetically positioned based on its 16S rRNA, pmoA, and mxaF gene sequences as a type II strain of theMethylocystis/Methylosinus group. A coculture of this strain with a Variovorax sp., when grown on <275 ppmv of CH4, had a Km(app) (129 to 188 nM) similar to that of the initial enrichment culture. The data suggest that the affinity of methanotrophic bacteria for CH4 varies with growth conditions and that the oxidation of atmospheric CH4 observed in this soil is carried out by type II methanotrophic bacteria which are similar to characterized species.