Gomaa Eman Zakaria
Department of Biological and Geological Sciences, Faculty of Education, Ain Shams University, Cairo, Egypt.
J Genet Eng Biotechnol. 2016 Dec;14(2):269-279. doi: 10.1016/j.jgeb.2016.10.001. Epub 2016 Nov 7.
Poly-γ-glutamic acid (γ-PGA) is a naturally occurring biopolymer made up of repeating units of glutamic acid and can be potentially used for multiple applications. This study compared the production of γ-PGA by and in GS and E media. The highest γ-PGA production was achieved using initial glycerol concentration of 40 and 80 g/l, ammonium chloride as the nitrogen source, 20 g/l glutamic acid at pH 6.5 for 72 h using E medium. On characterization, it was observed that glutamic acid was the sole component of the purified material. It contained a mixture of Na-γ-PGA and H-γ-PGA. The survival of probiotics during freeze drying was improved by combining them with γ-PGA polymer. For 10% γ-PGA protected the cells significantly than 10% sucrose during freeze drying. γ-PGA protection was shown to improve the viability of probiotic bacteria in orange juice for 40 days. No considerable change was observed in the concentrations of citric acid, malic acid and ascorbic acid when probiotic bacteria and γ-PGA were introduced into orange juice and hence, it could be used as a non-dairy delivery platform for these bacteria.
聚-γ-谷氨酸（γ-PGA）是一种天然存在的生物聚合物，由谷氨酸的重复单元组成，具有多种潜在用途。本研究比较了[具体菌株1]和[具体菌株2]在GS培养基和E培养基中γ-PGA的产量。使用E培养基，初始甘油浓度为40和80 g/l、氯化铵作为氮源、20 g/l谷氨酸、pH值为6.5，培养72小时时，γ-PGA产量最高。经表征发现，纯化后的物质中谷氨酸是唯一成分，它包含Na-γ-PGA和H-γ-PGA的混合物。将益生菌与γ-PGA聚合物结合可提高其冻干存活率。对于[具体菌株]，在冻干过程中，10%的γ-PGA比10%的蔗糖能更显著地保护细胞。γ-PGA保护作用可使益生菌在橙汁中的活力提高40天。将益生菌和γ-PGA引入橙汁后，柠檬酸、苹果酸和抗坏血酸的浓度未观察到显著变化，因此，它可作为这些细菌的非乳制品递送平台。
