Department of Chemistry, Wroclaw University of Environmental and Life Sciences, Norwida 25, 50-375 Wrocław, Poland.
Istituto di Scienze e Tecnologie Chimiche "Giulio Natta" (SCITEC)-CNR, Via Mancinelli 7, I-20131 Milan, Italy.
Molecules. 2020 Jul 2;25(13):3024. doi: 10.3390/molecules25133024.
Microbial conversion of oleic acid () to form value-added industrial products has gained increasing scientific and economic interest. So far, the production of natural lactones with flavor and fragrance properties from fatty acids by non-genetically modified organisms (non-GMO) involves whole cells of bacteria catalyzing the hydration of unsaturated fatty acids as well as yeast strains responsible for further β-oxidation processes. Development of a non-GMO process, involving a sole strain possessing both enzymatic activities, significantly lowers the costs of the process and constitutes a better method from the customers' point of view regarding biosafety issues. Twenty bacteria from the genus of , , , , , , and were screened for oxidative functionalization of oleic acid (). PCM525 was selected as the sole strain catalyzing the one-pot transformation of oleic acid () into natural valuable peach and strawberry-flavored γ-dodecalactone () used in the food, beverage, cosmetics and pharmaceutical industries. Based on the identified products formed during the process of biotransformation, we clearly established a pathway showing that oleic acid () is hydrated to 10-hydroxystearic acid (), then oxidized to 10-ketostearic acid (), giving 4-ketolauric acid () after three cycles of β-oxidation, which is subsequently reduced and cyclized to γ-dodecalactone () (Scheme 1). Moreover, three other strains ( DSM44534, PCM2166, sp. DSM44016), with high concomitant activities of oleate hydratase and alcohol dehydrogenase, were identified as efficient producers of 10-ketostearic acid (), which can be used in lubricant and detergent formulations. Considering the prevalence of γ-dodecalactone () and 10-ketostearic acid () applications and the economic benefits of sustainable management, microbial bioconversion of oleic acid () is an undeniably attractive approach.
微生物将油酸（）转化为附加值工业产品的方法引起了越来越多的科学和经济关注。迄今为止，通过非转基因生物（non-GMO）从脂肪酸生产具有风味和香气特性的天然内酯，涉及到细菌的整个细胞催化不饱和脂肪酸的水合作用，以及负责进一步β-氧化过程的酵母菌株。开发一种非转基因生物工艺，涉及到仅具有两种酶活性的单一菌株，可以显著降低该工艺的成本，并且从客户的角度来看，在生物安全性问题上是一种更好的方法。从属筛选了 20 种细菌，包括 、 、 、 、 、 ，以氧化功能化油酸（）。选择 PCM525 作为唯一的菌株，可催化油酸（）一锅转化为天然有价值的桃和草莓味γ-十二内酯（），用于食品、饮料、化妆品和制药行业。基于生物转化过程中形成的鉴定产物，我们明确建立了一条途径，表明油酸（）水合生成 10-羟基硬脂酸（），然后氧化生成 10-酮硬脂酸（），经过三轮β-氧化生成 4-酮月桂酸（），然后还原和环化生成γ-十二内酯（）（方案 1）。此外，还鉴定出另外 3 种菌株（DSM44534、PCM2166、sp.DSM44016）具有高的油酸酯水合酶和醇脱氢酶的伴随活性，是 10-酮硬脂酸（）的有效生产菌，可用于润滑剂和洗涤剂配方。考虑到γ-十二内酯（）和 10-酮硬脂酸（）的应用广泛和可持续管理的经济效益，微生物转化油酸（）无疑是一种有吸引力的方法。
