温特曲霉转富马酸为L-苹果酸的初步研究*

从大量霉菌中选育到一株具有较高富马酸酶活性的温特曲霉(Aspergillus wentii) A5-61。在摇瓶培养条件下，32℃ 96小时，产L-苹果酸达10.49g/100ml，对富马酸的转化率达90.80%。利用菌体细胞，进行酶转化试验，结果表明：1.6g湿菌体接入25ml含富马酸10.0%（用NaOH中和至pH7.0）的转化液中，35℃16～24小时，连续转化三次，分别产生L—苹果酸9.61g/100ml、9.73g/100ml、6.93g/100ml。对菌体整体细胞酶学性质的研究表明，其最适反应温度35℃，最适反应pH7.0，Cu2＋对该酶有明显的抑制作用，该酶的Km＝0.154mol/L，Vmax＝0.0571mol/L·h。

STUDY ON THE CONVERSION FROM FUMARIC ACID TO L-MALIC ACID BY ASPERGILLUS WENTII

Aspergillus wentii A5-61 with higher fumarase activity was screened from a large number of molds.According to the experimental results. In shake flask culture， L-Malic acid yields was 10.49 g/100ml at 32℃ for 96h， and the conversion rate of fumaric acid was 90.80%. The conversion from fumaric acid to L-malic acid by reusing intact cells showed that intact cells could be used for three times and L-malic acid was produced at yield of 9.61g/100ml， 9.73g/100ml and 6.95g/100ml respectively at 35℃ for 16～24h，when 1.6g wet cells was added to 25ml 10.0% fumaric acid ( neutralized to pH7.0 by NaOH )conversion solution. The study on some properties of intact cells enzyme indicated that the optimum conditions for activity were pH7.0 ，temperature 35℃; the addition of Cu2＋ had an obvious inhibiting effect on the enzyme ; Km＝0.154mol/L， Vmax＝0.0571mol/L·h.