Ferber E, Schlecht S, Fromme I
Zentralbl Bakteriol Orig A. 1976 Nov;236(2-3):275-87.
Non-covalently bound lipids were extracted from 2 Salmonella minnesota S forms and 5 R mutants (chemotype Ra-Re) isolated from these strains. The lipids were subsequently analysed with regard to fatty acid composition. The extracts were free of lipid A, as determined by absence of beta-hydroxymyristic acid. The fatty acid distribution in the lipids of the two S forms, cultivated at 37 degrees C to the beginning of the stationary phase of growth, agreed very closely, and the values corresponded to those reported in the literature for S. typhimurium. In contrast, there was a progressive reduction in the content of C17- and C19-cyclopropane fatty acids, going from Ra-Rc mutants. The total cyclopropane fatty acids decreased from approximately 30% (Ra) to approximately 7% (Rc). The lipids from the Rd1 and the Re mutants had a fatty acid composition identical to that of the Rc mutant. The decrease in cyclopropane fatty acid content was compensated for in all strains by an increase in the corresponding unsaturated fatty acids (16:1; 18:1). Variations in the incubation temperature (30, 37, 41 degrees C) affected the ratio of the single fatty acids as determined for the Ra, Rc and Re mutants. The content of unsaturated fatty acids increased with the reduction in temperature, while the proportion of cyclopropane fatty acids decreased (stationary growth phase). These changes were much more pronounced with the Ra mutant than with the Rc and the Re mutants. The differences among the mutants with regard to fatty acid distribution were apparent at all temperature levels. In addition, the fatty acid composition of the lipids varied with the phase of growth, as already reported for E. coli and other gram-negative organisms. The content of cyclopropane fatty acids increased from the exponential to the stationary phases, with simultaneous reduction in the proportion of corresponding unsaturated fatty acids. Again, the lipid composition of the Ra mutant varied to a greater extent than did that of the Rc and the Re mutants. Similar changes appeared in the phosphatidyl ethanolamine fractions of the three mutants. There were also changes in the neutral lipids that agreed in part with those of the total lipids. The cause of the reduced cyclopropane fatty acid synthesis in S. minnesota R mutants possessing an incomplete LPS-core structure (Rb2-Re) is at present unknown. The physiological significance of these findings as well remains for the moment speculative, as the functional role of cyclopropane fatty acids in biological membranes has not yet been elucidated. Possible relations to membrane permeability and to transfer of antibiotics are discussed.
从2株明尼苏达沙门氏菌S型菌株和从这些菌株中分离出的5株R突变体（化学型Ra - Re）中提取非共价结合的脂质。随后对脂质的脂肪酸组成进行了分析。提取物中不含脂质A，这通过缺乏β - 羟基肉豆蔻酸得以确定。在37℃培养至生长稳定期开始时，两种S型菌株脂质中的脂肪酸分布非常接近，其数值与文献中报道的鼠伤寒沙门氏菌的数值相符。相比之下，从Ra到Rc突变体，C17 - 和C19 - 环丙烷脂肪酸的含量逐渐降低。环丙烷脂肪酸的总量从约30%（Ra）降至约7%（Rc）。Rd1和Re突变体的脂质脂肪酸组成与Rc突变体相同。在所有菌株中，环丙烷脂肪酸含量的降低都被相应不饱和脂肪酸（16:1；18:1）含量的增加所补偿。培养温度（30、37、41℃）的变化影响了为Ra、Rc和Re突变体测定的单一脂肪酸的比例。不饱和脂肪酸的含量随着温度降低而增加，而环丙烷脂肪酸的比例降低（稳定生长期）。这些变化在Ra突变体中比在Rc和Re突变体中更为明显。在所有温度水平下，突变体之间在脂肪酸分布方面的差异都很明显。此外，脂质的脂肪酸组成随生长阶段而变化，这与大肠杆菌和其他革兰氏阴性菌的情况已报道的一致。环丙烷脂肪酸的含量从指数期到稳定期增加，同时相应不饱和脂肪酸的比例降低。同样，Ra突变体的脂质组成变化程度比Rc和Re突变体更大。在这三种突变体的磷脂酰乙醇胺组分中也出现了类似的变化。中性脂质也有变化，部分与总脂质的变化一致。目前尚不清楚具有不完整脂多糖核心结构（Rb2 - Re）的明尼苏达沙门氏菌R突变体中环丙烷脂肪酸合成减少的原因。这些发现的生理意义目前也仍然是推测性的，因为环丙烷脂肪酸在生物膜中的功能作用尚未阐明。文中讨论了与膜通透性和抗生素转移的可能关系。
