L-丙氨酸转化菌发酵条件的优化

产L-天冬氨酸-β-脱羧酶(L-aspartate-β-decarboxylase,Asd)菌株以L-天冬氨酸(L-aspartic acid,L-Asp)为底物转化生产L-丙氨酸,通过单因素及正交设计试验对睾丸酮丛毛单胞菌HY-08D培养基组成及发酵条件进行优化。结果表明,最佳培养基组成:富马酸1.0%、L-Asp 1.0%、谷氨酸1.0%、玉米浆干粉0.6%、酵母粉0.8%、氯化钠0.7%、磷酸二氢钾0.15%、硫酸镁0.1%,pH 6.0。产酶菌株HY-08D转化用培养液采用三级扩培,一级接二级使用0.1%低接种量,二级接三级使用10%的接种量,最适通气量为10 L/min。优化后培养液中HY-08D菌体量和酶活较初始提高约1倍,培养周期缩短6 h~8 h。

Fermentation Conditions Optimization of L-Alanine-producing Bacteria

The L-aspartate-β-decarboxylase(Asd)-producing strain transforms L-alanine with L-aspartic acid(L-Asp)as substrate.The single factor and orthogonal experiments were employed to optimize the culture medium and fermentation conditions for Asd production by Comamonas testosteroni HY-08D.The optimal fermentation medium consisted of the following:fumaric acid 1.0%,L-Asp 1.0%,glutamic acid 1.0%,corn starch powder 0.6%,yeast extract 0.8%,NaCl 0.7%,KH2PO40.15%,MgSO40.1%,pH 6.0.The medium for the transformation of HY-08D strain was expanded in three-stage culture.A low inoculation amount of 0.1%was used from the first to the second stage.10%quantity of inoculation was used from the second to the third stage.The optimal ventilatory capacity was 10 L/min.The biomass and enzyme activity of HY-08D in optimized medium had doubled,and the culture period was shortened by 6 h-8 h compared with the initial state.