海洋细菌Pseudoalteromonas sp. HL9的筛选鉴定及产磷脂酶B性质

从黄海海泥中筛选产磷脂酶菌株，其中酶活力最高的HL9鉴定为假交替单胞菌属（Pseudoalteromonas）。该菌株最佳生长培养基组成为米糠与酵母粉，最佳生长pH 8.0、NaCl质量浓度30 g/L、培养温度25 ℃。优化后产酶最高发酵条件：发酵培养基配方为10 g/L麸皮和5 g/L鱼粉蛋白胨，NaCl 20 g/L，pH 8.5，接种量2%，30 ℃培养48 h。薄层层析和气相色谱分析表明，菌株HL9产磷脂酶B，且磷脂酶B水解sn-2酰基的产物占70%。该酶的最适反应温度和pH值分别为45 ℃和7.5。Ca2＋、Co2＋、Mn2＋等金属离子对酶活力有促进作用，Cu2＋对酶活力有抑制作用。磷脂酶B在有机溶剂中可以保持80%的酶活力。反应温度高和碱性条件等催化特性使该酶具有较好应用前景，研究结果也为进一步探索该酶的结构与功能奠定基础。

Screening and Identification of Marine Bacterium Pseudoalteromonas sp. HL9 and Characteristics of Phospholipase B Produced by It

In this study, we screened and identified Pseudoalteromonas sp. HL9 with the capacity to produce phospholipase B from the mud of the Yellow Sea. The optimal growth medium for this strain consisted of rice bran, yeast powder, and 30 g/L NaCl at pH 8.0, and the optimal culture temperature was 25 ℃. The optimal fermentation conditions that provided maximum phospholipase B activity were found to be culture at 30 ℃ for 48 h in a medium containing rice bran 10 g/L, fish meal peptone 5 g/L, and NaCl 20 g/L at pH 8.5. Thin layer chromatography (TLC) and gas chromatography (GC) results showed that strain HL9 could produce phospholipase B, and that the hydrolysate of sn-2 acyl groups with the enzyme accounted for 70% of the total. The optimal temperature and pH of this enzyme were 45 ℃ and 7.5, respectively. Ca2+, Co2+ and Mn2+ could enhance the activity of phospholipase B, while Cu2+ had an inhibitory effect on the enzyme activity. The phospholipase B retained 80% of its activity in organic solvents. In summary, this enzyme has good catalytic properties at high temperature or alkaline conditions and thus has broad application prospects. The results of this study will lay the foundation for investigating its structure and function.