Abstract: 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.

Key words: Pseudoalteromonas; phospholipase B; characteristics