甲苯胁迫下有机溶剂耐受菌Anoxybacillus flavithermus ssp．yunnanesis E13T膜脂肪酸的变化

Adaptation of Anoxybacillus flavithermus ssp．Yunnanesis E13T to toluene at the level of fatty acid composition of membrane

摘要:

摘要:【目的】探讨目前唯一具有有机溶剂耐受性的嗜热细菌新物种Anoxybacillus flavithermus ssp．yunnanesis E13T甲苯胁迫下膜脂肪酸的变化。【方法】在不同条件下培养菌株E13T，收集细胞，提取脂肪酸，采用气相色谱-质谱(GC-MS)对脂肪酸进行定量测定分析。【结果】0.3% (V/V)甲苯胁迫下生长时，菌株E13T是在从延滞期进入初始生长的时刻显著上调饱和直链脂肪酸含量，然后随着菌体的生长，饱和直链脂肪酸的含量持续减少;在100%甲苯幸存实验中，菌株E13T的饱和直链脂肪酸的增加幅度更为显著。【结论】与常温下的有机溶剂耐受菌一样，A．flavithermus ssp．yunnanesis E13T也是通过调节细胞膜上的脂肪酸，促使细胞膜变硬以抵御甲苯毒性。但是它是通过调节饱和直链脂肪酸，而不是像常温下的有机溶剂耐受菌那样调节不饱和脂肪酸。

Abstract:

Abstract:［Objective］ Anoxybacillus flavithermus subsp．yunnanensis is now the only species of thermophilic bacteria able to tolerate toxic solvents at high temperature．The adaptive responses of A．flavithermus subsp． yunnanensis E13T to toluene on the level of fatty acid composition of membrane were studied in detail．［Methods］The extraction of fatty acids was performed according to the method described in the Sherlock Microbial Identification System manual．The fatty acid compositions were analyzed by gas chromatography mass spectrometry (GC-MS)．［Results］In presence of 0.3% (V/V) toluene，key moment to adapt the saturated straight-chain fatty acids was that when cells grew from the lag phase to the initial growth phase in liquid． The saturated straight-chain fatty acids were continuously decreased as the strain E13T to grow．In survival of the cells in 100% toluene，the saturated straight-chain fatty acids increased significantly.［Conclusion］A．flavithermus ssp． yunnanesis E13T alters its membrane fluidity via fatty acid composition to become more rigid when it is exposed to solvent，which is consistent that commonly found in mesophilic organic solvent-tolerant bacteria． However，it adapted its membrane by increasing straight-chain saturated fatty acids，rather than unsaturated fatty acids，which was demonstrated in mesophilic organic solvent-tolerant bacteria．