Fritsch Caroline, Jänsch André, Ehrmann Matthias A, Toelstede Simone, Vogel Rudi F
Fraunhofer Institute for Process Engineering and Packaging IVV, Giggenhauser Straße 35, Freising, Germany.
Technische Universität München, Technische Mikrobiologie Weihenstephan, Gregor-Mendel-Straße 4, Freising, Germany.
Curr Microbiol. 2017 Feb;74(2):247-256. doi: 10.1007/s00284-016-1182-x. Epub 2016 Dec 21.
A high variety of plants that are used for food production contain esterified hydroxycinnamic acids. As their free forms display several benefits, like an enhanced absorption in human intestinal tract, anti-oxidative and anti-carcinogenic effects, an improved protein solubility and reduced discoloration, the microbial ability to cleave the ester bond is highly desired. In order to examine potential fermentation strains for this purpose, six different lactic acid bacteria and one bifidobacterial strain were screened for their ability to degrade esterified hydroxycinnamic acids because these strains are commonly used for fermentation of plant-based foods. Moreover, their cinnamoyl esterase activity was examined by molecular biological analyses. The enzymes were heterologously expressed in Escherichia coli, purified and biochemically characterized. The purified esterases with a molecular mass around 27-29 kDa had their optimum predominantly between pH 7 and 8 at 20-30 °C. Bifidobacterium animalis subsp. lactis, Lactobacillus gasseri, Lactobacillus acidophilus, Lactobacillus plantarum and Lactobacillus fermentum displayed activities against a broad substrate range (methyl caffeate, methyl trans-p-coumarate, chlorogenic acid as well as partially ethyl ferulate). Concerning substrate affinity, reaction velocity, thermal and pH stability, Lactobacillus gasseri showed the overall best performance. The herein studied lactic acid- and bifidobacteria are promising for the production of fermented plant-based foods with an increased quality and nutritional value.
多种用于食品生产的植物都含有酯化羟基肉桂酸。由于其游离形式具有多种益处，如在人体肠道中吸收增强、具有抗氧化和抗癌作用、提高蛋白质溶解度以及减少变色，因此人们非常期望微生物具有裂解酯键的能力。为了为此目的筛选潜在的发酵菌株，对六种不同的乳酸菌和一种双歧杆菌菌株进行了筛选，考察它们降解酯化羟基肉桂酸的能力，因为这些菌株常用于植物性食品的发酵。此外，通过分子生物学分析检测了它们的肉桂酰酯酶活性。这些酶在大肠杆菌中进行异源表达、纯化并进行了生化特性鉴定。纯化后的酯酶分子量约为27 - 29 kDa，其最适条件主要为20 - 30℃、pH值7至8。动物双歧杆菌乳亚种、加氏乳杆菌、嗜酸乳杆菌、植物乳杆菌和发酵乳杆菌对多种底物（咖啡酸甲酯、反式对香豆酸甲酯、绿原酸以及部分阿魏酸乙酯）都有活性。在底物亲和力、反应速度、热稳定性和pH稳定性方面，加氏乳杆菌总体表现最佳。本文研究的乳酸菌和双歧杆菌有望用于生产质量和营养价值更高的植物性发酵食品。
