Abstract：
It is well established that Staphylococcus aureus can incorporate exogenous straight-chain unsaturated fatty acids (SCUFAs) into membrane phospho- and glyco-lipids from various sources in supplemented culture media and when growing in vivo during infection. Given the enhancement of membrane fluidity when oleic acid (C18:1Δ9) is incorporated into lipids, we were prompted to examine the effect of medium supplementation with C18:1Δ9 on growth at low temperatures. C18:1Δ9 supported the growth of a cold-sensitive, branched-chain fatty acid (BCFA)-deficient mutant at 12°C. Interestingly, we found similar results in the BCFA-sufficient parental strain, supported by the fact that the incorporation of C18:1Δ9 into the membrane increased membrane fluidity in both strains. We show that the incorporation of C18:1Δ9 and its elongation product C20:1Δ11 into membrane lipids was required for growth stimulation and relied on a functional FakAB incorporation system. Lipidomics analysis of the phosphatidylglycerol and diglycosyldiacylglycerol lipid classes revealed major impacts of C18:1Δ9 and temperature on lipid species. Growth at 12°C in the presence of C18:1Δ9 also led to increased production of the carotenoid pigment staphyloxanthin. The enhancement of growth by C18:1Δ9 is an example of homeoviscous adaptation to low temperatures utilizing an exogenous fatty acid. This may be significant in the growth of S. aureus at low temperatures in foods that commonly contain C18:1Δ9 and other SCUFAs in various forms.
OBJECTIVE: We show that Staphylococcus aureus can use its known ability to incorporate exogenous fatty acids to enhance its growth at low temperatures. Individual species of phosphatidylglycerols and diglycosyldiacylglycerols bearing one or two degrees of unsaturation derived from the incorporation of C18:1Δ9 at 12°C are described for the first time. In addition, enhanced production of the carotenoid staphyloxanthin occurs at low temperatures. The studies describe a biochemical reality underlying membrane biophysics. This is an example of homeoviscous adaptation to low temperatures utilizing exogenous fatty acids over the regulation of the biosynthesis of endogenous fatty acids. The studies have likely relevance to food safety in that unsaturated fatty acids may enhance the growth of S. aureus in the food environment.
OBJECTIVE: We show that Staphylococcus aureus can use its known ability to incorporate exogenous fatty acids to enhance its growth at low temperatures. Individual species of phosphatidylglycerols and diglycosyldiacylglycerols bearing one or two degrees of unsaturation derived from the incorporation of C18:1Δ9 at 12°C are described for the first time. In addition, enhanced production of the carotenoid staphyloxanthin occurs at low temperatures. The studies describe a biochemical reality underlying membrane biophysics. This is an example of homeoviscous adaptation to low temperatures utilizing exogenous fatty acids over the regulation of the biosynthesis of endogenous fatty acids. The studies have likely relevance to food safety in that unsaturated fatty acids may enhance the growth of S. aureus in the food environment.
摘要：
众所周知,金黄色葡萄球菌可以在补充培养基中以及在感染期间在体内生长时将外源直链不饱和脂肪酸(SCUFA)掺入来自各种来源的膜磷酸-和糖脂中。考虑到当油酸(C18:1Δ9)掺入到脂质中时膜流动性的增强,提示我们检查在低温下补充C18：1Δ9的培养基对生长的影响。C18：1Δ9支持冷敏感的生长，12℃支链脂肪酸(BCFA)缺陷型突变体有趣的是,我们在BCFA充足的亲本菌株中发现了类似的结果，受以下事实的支持：将C18：1Δ9掺入膜中会增加两种菌株的膜流动性。我们表明，生长刺激需要将C18：1Δ9及其延伸产物C20：1Δ11掺入膜脂质中，并且依赖于功能性FakAB掺入系统。磷脂酰甘油和二糖基二酰基甘油脂质类别的脂质组学分析揭示了C18：1Δ9和温度对脂质种类的主要影响。在C18：1Δ9存在下，在12°C下的生长也导致类胡萝卜素色素黄黄素的产量增加。C18：1Δ9的生长增强是利用外源脂肪酸对低温的稳态粘性适应的一个例子。这在金黄色葡萄球菌在低温下在通常含有C18:1Δ9和各种形式的其他SCUFA的食物中的生长中可能是显著的。
目的：我们表明金黄色葡萄球菌可以利用其已知的掺入外源脂肪酸的能力来增强其在低温下的生长。首次描述了在12°C下掺入C18：1Δ9而具有一个或两个不饱和度的磷脂酰甘油和二糖基二酰基甘油的单个物种。此外,在低温下增加类胡萝卜素的产生。这些研究描述了膜生物物理学基础的生化现实。这是利用外源脂肪酸而不是调节内源脂肪酸的生物合成的对低温的稳态粘性适应的实例。这些研究可能与食品安全有关，因为不饱和脂肪酸可能会增强食物环境中金黄色葡萄球菌的生长。
目的：我们表明金黄色葡萄球菌可以利用其已知的掺入外源脂肪酸的能力来增强其在低温下的生长。首次描述了在12°C下掺入C18：1Δ9而具有一个或两个不饱和度的磷脂酰甘油和二糖基二酰基甘油的单个物种。此外,在低温下增加类胡萝卜素的产生。这些研究描述了膜生物物理学基础的生化现实。这是利用外源脂肪酸而不是调节内源脂肪酸的生物合成的对低温的稳态粘性适应的实例。这些研究可能与食品安全有关，因为不饱和脂肪酸可能会增强食物环境中金黄色葡萄球菌的生长。
