S. N. Winogradsky Institute of Microbiology, Russian Academy of Sciences, Moscow 117312, Russia.
Max-Planck-Institut für terrestrische Mikrobiologie, D-35043 Marburg, Germany.
Int J Syst Evol Microbiol. 2011 Oct;61(Pt 10):2456-2463. doi: 10.1099/ijs.0.028118-0. Epub 2010 Nov 19.
Two strains of aerobic methanotrophic bacteria, AR4(T) and SOP9, were isolated from acidic (pH 3.8-4.0) Sphagnum peat bogs in Russia. Another phenotypically similar isolate, strain LAY, was obtained from an acidic (pH 4.0) forest soil in Germany. Cells of these strains were Gram-negative, non-pigmented, non-motile, thin rods that multiplied by irregular cell division and formed rosettes or amorphous cell conglomerates. Similar to Methylocella species, strains AR4(T), SOP9 and LAY possessed only a soluble form of methane monooxygenase (sMMO) and lacked intracytoplasmic membranes. Growth occurred only on methane and methanol; the latter was the preferred growth substrate. mRNA transcripts of sMMO were detectable in cells when either methane or both methane and methanol were available. Carbon was assimilated via the serine and ribulose-bisphosphate (RuBP) pathways; nitrogen was fixed via an oxygen-sensitive nitrogenase. Strains AR4(T), SOP9 and LAY were moderately acidophilic, mesophilic organisms capable of growth between pH 3.5 and 7.2 (optimum pH 4.8-5.2) and at 4-33 °C (optimum 20-23 °C). The major cellular fatty acid was 18 : 1ω7c and the quinone was Q-10. The DNA G+C content was 55.6-57.5 mol%. The isolates belonged to the family Beijerinckiaceae of the class Alphaproteobacteria and were most closely related to the sMMO-possessing methanotrophs of the genus Methylocella (96.4-97.0 % 16S rRNA gene sequence similarity), particulate MMO (pMMO)-possessing methanotrophs of the genus Methylocapsa (96.1-97.0 %), facultative methylotrophs of the genus Methylovirgula (96.1-96.3 %) and non-methanotrophic organotrophs of the genus Beijerinckia (96.5-97.0 %). Phenotypically, strains AR4(T), SOP9 and LAY were most similar to Methylocella species, but differed from members of this genus by cell morphology, greater tolerance of low pH, detectable activities of RuBP pathway enzymes and inability to grow on multicarbon compounds. Therefore, we propose a novel genus and species, Methyloferula stellata gen. nov., sp. nov., to accommodate strains AR4(T), SOP9 and LAY. Strain AR4(T) ( = DSM 22108(T) = LMG 25277(T) = VKM B-2543(T)) is the type strain of Methyloferula stellata.
两株需氧甲烷营养细菌 AR4(T) 和 SOP9 从俄罗斯酸性 (pH 3.8-4.0) 泥炭沼泽中分离出来。另一株表型相似的分离株 LAY 则从德国酸性 (pH 4.0) 森林土壤中获得。这些菌株的细胞为革兰氏阴性、非色素、非运动、薄杆状，通过不规则的细胞分裂增殖，并形成玫瑰花结或无定形细胞聚集体。与 Methylocella 属类似，AR4(T)、SOP9 和 LAY 菌株仅具有可溶性甲烷单加氧酶 (sMMO)，缺乏细胞内膜。这些菌株仅在甲烷和甲醇上生长；后者是首选的生长底物。当存在甲烷或甲烷和甲醇时，可在细胞中检测到 sMMO 的 mRNA 转录物。碳通过丝氨酸和核酮糖-1,5-二磷酸 (RuBP) 途径同化；氮通过氧敏感的固氮酶固定。菌株 AR4(T)、SOP9 和 LAY 是中度嗜酸、嗜温的生物体，能够在 pH 3.5 和 7.2 之间生长 (最佳 pH 4.8-5.2) 和 4-33°C (最佳 20-23°C)。主要细胞脂肪酸为 18:1ω7c，醌为 Q-10。DNA G+C 含量为 55.6-57.5 mol%。这些分离株属于 Beijerinckiaceae 科的 Alphaproteobacteria 类，与具有 sMMO 的甲烷营养菌 Methylocella 属 (16S rRNA 基因序列相似度为 96.4-97.0%)、具有颗粒状 MMO (pMMO) 的甲烷营养菌 Methylocapsa 属 (96.1-97.0%)、兼性甲基营养菌 Methylovirgula 属 (96.1-96.3%) 和非甲烷营养有机营养菌 Beijerinckia 属 (96.5-97.0%) 最为密切相关。表型上，菌株 AR4(T)、SOP9 和 LAY 与 Methylocella 属最为相似，但与该属成员的区别在于细胞形态、对低 pH 的耐受性、可检测的 RuBP 途径酶活性以及不能在多碳化合物上生长。因此，我们提出了一个新属和新种 Methyloferula stellata gen. nov.，sp. nov.，以容纳菌株 AR4(T)、SOP9 和 LAY。菌株 AR4(T)(=DSM 22108(T)=LMG 25277(T)=VKM B-2543(T)) 是 Methyloferula stellata 的模式株。
