Steryl Ester Formation and Accumulation in Steroid-Degrading Bacteria
Steryl Ester Formation and Accumulation in Steroid-Degrading Bacteria
复制标题
DOI：
10.1128/aem.02353-19
复制
发表时间：
2020-01-01
影响因子：
4.4
通讯作者：
Mohna, William W.
中科院分区：
文献类型：
--
作者：
Holert, Johannes;Brown, Kirstin;Mohna, William W.
甾基酯(Steryl esters，SE)是许多真核生物中重要的储存化合物，是细胞内脂滴的重要组成部分。在这里，我们证明了生长在甾醇上的选定的放线菌和变形杆菌也能够合成SES并将它们隔离在细胞质的脂滴中。我们发现胆固醇酯(CE)在放线杆菌属的红球菌属、分枝杆菌属和无枝杆菌属的成员中形成，也在蛋白细菌的胞弧菌目的几个成员中形成。Ces在氮素限制条件下积累最多，这表明在不利条件下，甾酯的形成对储存多余的能量和碳起着至关重要的作用。约氏红球菌RHA1能够合成植物甾醇酯和胆固醇酯，后者高达其细胞干重的7%和脂滴的69%。从RHA1中提纯的脂滴含有CES、游离胆固醇和三酰甘油。此外，我们还发现，当结核分枝杆菌与胆固醇和额外的脂肪酸底物一起生长时，它会形成CES。本研究为细菌全细胞体系在生物技术生产功能性食品和化妆品中的应用提供了基础。重要的产油细菌在生产三酰甘油和蜡酯等高价值中性脂肪方面显示出巨大的潜力。本研究描述了甾醇酯(Ses)作为中性储脂化合物在降解甾醇的油脂细菌中的形成，为利用在功能食品、营养食品和化妆品工业中潜在应用的细菌系统生产SES提供了基础。我们发现在氮限氮条件下，几种降解类固醇的放线菌和变形杆菌会形成胆固醇酯(CE)，这表明在不利条件下，这一过程在储存能量和碳方面发挥了重要作用。此外，在附加脂肪酸底物存在的情况下，生长在胆固醇上的结核分枝杆菌积累了CES。
Steryl esters (SEs) are important storage compounds in many eukaryotes and are often prominent components of intracellular lipid droplets. Here, we demonstrate that selected Actino- and Proteobacteria growing on sterols are also able to synthesize SEs and to sequester them in cytoplasmic lipid droplets. We found cholesteryl ester (CE) formation in members of the actinobacterial genera Rhodococcus, Mycobacterium, and Amycolatopsis, as well as several members of the proteobacterial Cellvibrionales order. CEs maximally accumulated under nitrogen-limiting conditions, suggesting that steryl ester formation plays a crucial role for storing excess energy and carbon under adverse conditions. Rhodococcus jostii RHA1 was able to synthesize phytosteryl and cholesteryl esters, the latter reaching up to 7% of its cellular dry weight and 69% of its lipid droplets. Purified lipid droplets from RHA1 contained CEs, free cholesterol, and triacylglycerols. In addition, we found formation of CEs in Mycobacterium tuberculosis when it was grown with cholesterol plus an additional fatty acid substrate. This study provides a basis for the application of bacterial whole-cell systems in the biotechnological production of SEs for use in functional foods and cosmetics.IMPORTANCE Oleaginous bacteria exhibit great potential for the production of high-value neutral lipids, such as triacylglycerols and wax esters. This study describes the formation of steryl esters (SEs) as neutral lipid storage compounds in sterol-degrading oleaginous bacteria, providing a basis for biotechnological production of SEs using bacterial systems with potential applications in the functional food, nutraceutical, and cosmetic industries. We found cholesteryl ester (CE) formation in several sterol-degrading Actino- and Proteobacteria under nitrogen-limiting conditions, suggesting an important role of this process in storing energy and carbon under adverse conditions. In addition, Mycobacterium tuberculosis grown on cholesterol accumulated CEs in the presence of an additional fatty acid substrate.