酶法生产鸟氨酸菌株的筛选与培养

Screening of bacterium for the conversion of arginine into ornithine by arginase

从土壤中筛选到一株可以利用胞内精氨酸酶生产鸟氨酸的菌株XT-025,通过形态特征、生理生化特性及16S rRNA基因序列分析,初步鉴定为苏云金芽孢杆菌(Bacillus thuringiensis),这是首次发现该种微生物可用以生产鸟氨酸。通过对其培养条件和转化条件的优化,确定了最佳的培养时间为24 h,最合适的转化液成分为0.3 mol/L的碳酸盐缓冲液,V(Na2CO3)∶V(NaHCO3)为8∶2。同时发现Mn2+对精氨酸酶有很强激活作用,在添加适量Mn2+的条件下,鸟氨酸的产量能够达到50 g/L,精氨酸摩尔转化率达到100%,而Sn4+和Cu2+则会使酶完全失活。

A strain of bacteria XT-025 for producing was identified as Bacillus thuringiensis according to ornithine by arginase was screened from soil. This strain its morphology, physiological characteristics and 16S ribosomal RNA gene sequence. This is the first report of the production of ornithine by this microbe. The optimum culture time was found to be 24 h with a cushion solution composed of 0.3 mol/L carbonate and V （Na2CO3） ： V （NaHCO3） = 8：2. It was found that Mn^2＋ can activate arginase and by adding appropriate concentrations of Mn^2＋, the yield of ornithine can reach 50 g/L and the molar conversion rate of arginine can reach 100%. In contrast, Sn^4 ＋ and Cu^2 ＋ were found to inhibit the reaction.