酶法生产鸟氨酸菌株的筛选与培养

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24h，最合适的转化液成分为0.3mol/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50g/L，精氨酸摩尔转化率达到100%，而Sn⁴⁺和Cu²⁺则会使酶完全失活。

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

A strain of bacteria XT-025 for producing ornithine by arginase was screened from soil. This strain was identified as Bacillus thuringiensis according to its morphology, physiological characteristics and 16S ribo-somal 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 0.3mol/L carbonate and V(Na_2CO_3): V (NaHCO_3) =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.