Jahnke L L, Nichols P D
J Bacteriol. 1986 Jul;167(1):238-42. doi: 10.1128/jb.167.1.238-242.1986.
Methylococcus capsulatus contained extensive intracytoplasmic membranes when grown in fed-batch cultures over a wide range of oxygen tensions (0.1 to 10.6%, vol/vol) and at a constant methane level. Although the biomass decreased as oxygen levels were lowered, consistently high amounts of phospholipid and methyl sterol were synthesized. The greatest amounts of sterol and phospholipid were found in cells grown between 0.5 and 1.1% oxygen (7.2 and 203 mumol/g [dry weight], respectively). While sterol was still synthesized in significant amounts in cells grown at 0.1% oxygen, the major sterol product was the dimethyl form. Analysis by capillary gas chromatography-mass spectrophotometry showed that the phospholipid esterified fatty acids were predominantly 16:0 and 16:1 and that the hexadecenoates consisted of cis delta 9, delta 10, and delta 11 isomers. At low oxygen tensions, the presence of large amounts (25%) of cyclopropane fatty acids (cy 17:0) with the methylene groups at the delta 9, delta 10, and delta 11 positions was detected. Although the delta 9 monoenoic isomer was predominant, growth at low oxygen levels enhanced the synthesis of the delta 10 isomers of 16:1 and cy 17:0. As the oxygen level was increased, the amount of cyclopropanes decreased, such that only a trace of cy 17:0 could be detected in cells grown at 10.6% oxygen. Although M. capsulatus grew at very low oxygen tensions, this growth was accompanied by changes in the membrane lipids.
荚膜甲基球菌在补料分批培养中，于较宽的氧分压范围（0.1%至10.6%，体积/体积）及恒定的甲烷水平下生长时，含有大量胞质内膜。尽管随着氧水平降低生物量减少，但仍持续合成大量磷脂和甲基甾醇。在氧含量为0.5%至1.1%之间生长的细胞中，甾醇和磷脂的含量最高（分别为7.2和203 μmol/g[干重]）。虽然在氧含量为0.1%时生长的细胞中仍大量合成甾醇，但其主要甾醇产物是二甲基形式。毛细管气相色谱 - 质谱分析表明，磷脂酯化脂肪酸主要为16:0和16:1，十六碳烯酸由顺式δ9、δ10和δ11异构体组成。在低氧分压下，检测到大量（25%）在δ9、δ10和δ11位置带有亚甲基的环丙烷脂肪酸（cy 17:0）。尽管δ9单烯异构体占主导，但在低氧水平下生长会增强16:1和cy 17:0的δ10异构体的合成。随着氧水平升高，环丙烷的量减少，以至于在氧含量为10.6%时生长的细胞中只能检测到微量的cy 17:0。尽管荚膜甲基球菌在极低的氧分压下生长，但这种生长伴随着膜脂的变化。
