固定化玫瑰微球菌发酵产海藻糖合成酶系

以聚氨酯为载体固定化培养玫瑰微球菌，发酵生产海藻糖合成酶系麦芽糖苷基海藻糖合成酶MTSase和麦芽糖苷基海藻糖水解酶MTHase。考察了细胞固定化对菌体生长及产酶的影响， 对固定化细胞重复批次发酵换液条件进行了初探。固定化细胞发酵40h，酶活达到最大值，产酶周期缩短了56h，细胞干质量和酶活分别达到12g/L和52u/mL，比游离细胞发酵提高了12%和33%。重复批次发酵最佳的换液条件为发酵40h后，以40%的换液量每隔24h以等量新鲜培养基替换发酵液。在此条件下，重复发酵9批，连续230h菌体生物量及酶活无明显下降。在10L发酵罐中进行放大实验，酶活最高达到80u/mL，重复发酵7批，连续180h菌体生物量及酶活无明显下降，酶的时空产率达到56.9u/(L·h)，比单批发酵提高了42.5%。

Production of MTSase and MTHase by fermentation with immobilized Microccus roseus

Production of the enzymes MTSase and MTHase, which are capable of converting starch into trehalose, by fermentation with Microccus roseus immobilized on polyurethane foam (PUF), has been studied. Immobilization was found to lead to a marked incrase in the activity of Microccus roseus, giving a significant reduction in production time compared with that for the free cells (40h vs. 106h). After fermentation for 40h, the observed value of the the dry cell weight was 12g/L and that of the enzyme activity 52u/mL; these represent increases of 12% and 33% respectively over the values obtained with the free cells. The optimum conditions for repeated cycle batch fermentation were found to be : after an initial 40h of fermentation, 40% of the medium is replaced with fresh medium every 24 hours. Under these conditions, the immobilized cells could be used in 9 batch cycles, lasting 230h in total in flask fermentation and in 7 batch cycles lasting 180h in total in a 10L fermenter without any significant loss of biomass of activity. The rate of enzyme production reached a maximum of 56.9u/(L·h), an increase of 42.5% over that observed in a single fermentation.