胞外青霉素酰化酶产生菌的选育

利用纸片显色方法，从土壤甲诀速筛选出98株产胞外青霉素酰化酶的菌种，经复筛其中10株酶活力较高，经鉴定均属于巨大芽孢杆菌。经单株分离得46号菌，用这株菌进行了产酶条件的研究，在最适产酶条件下，酶话力比开始提高了3．6倍。在此基础上又进行了物理化学因素处理，得突变株UL-81，酶活力达720u／1 Ooml发酵液。对原株和突变株进行比较，发现UL-81菌落、细胞形态、诱导剂苯乙酸用量及添加时间等明显不同于原株。在500L罐发酵酶活达8 20u／1OOml发酵液，为开始酶活的16倍。

Screening of strain producing extracellular penicillin acylase]

Ninety-eight strains having extracellular penicillin acylase activity were derived from soil samples by colour-developing method. 10 strains of them possess higher activity of penicillin acylase. All of those are found to be Bacillus megaterium. The optimum condition of enzyme production was investigated with the strain No. 46 which is from No. 247 by single colony isolation. The productivity of penicillin acylase in the optimum condition have been enhanced 2.5 times more than that in the screening condition. The mutant strain, Bacillus megaterium UL-81, which penicillin acylase activity reached the level of 723u/100ml of broth was obtained from No. 46 by treatment with physical and chemical factors. The penicillin acylase activity of UL-81 can reach 820u/100 ml in 500L fermentor. The mutant strain differed from parent strain in the morphology of colony, the size of cells, the effect of concentration and the addition time of phenylacetic acid on the production of penicillin acylase.