一株新型烟叶淀粉降解菌的筛选鉴定及其发酵条件优化OA

To effectively reduce the starch content in tobacco leaves and improve the quality,a strain K1 with high-efficiency starch-degrading capability was isolated from the surface of tobacco leaves.Molecular biological identifica-tion confirmed that the strain was Bacillus rugosus.Based on single-factor experiments and response surface method-ology,the optimal fermentation conditions for the strain to degrade tobacco leaf starch were investigated.The results showed that the optimal carbon source,nitrogen source and inorganic salt were wheat bran,soybean meal and potas-sium dihydrogen phosphate(KH2 PO4),respectively.After optimization,the optimal fermentation conditions were determined as follows:wheat bran at 13.6 g·L-1,soybean meal at 11.7 g·L-1,KH2 PO4 at 12.5 g·L-1,initial pH value of 8.0,rotation speed of 200 r·min-1 and fermentation temperature of 32℃.Under these conditions,the amylase activity of the strain reached 145.08 U·mL-1.After fermentation,the starch content in tobacco leaves de-creased by 49.43%,while the contents of total sugar and reducing sugar increased by 9.11%and 11.05%,respec-tively.This study provides an excellent strain resource for degrading tobacco leaf starch and improving tobacco leaf quality,and lays a foundation for the further development and utilization of tobacco leaf starch-degrading bacteria.