纳豆提取物对两株细菌的抑制作用及其培养条件的优化

为了寻找天然的生物防腐剂和微生态制剂,对纳豆提取物的抑菌作用及其培养条件进行了研究。结果显示：最佳培养条件是接种量6%、含水量60%、物料厚度1.92 cm、后熟时间2 d;抑制金黄色葡萄球菌RCEF091013的碳源、添加物、无机盐和发酵时间的最佳因素水平组合为葡萄糖6%、酵母粉1%、MgSO40.3%、发酵时间48 h;抑制大肠杆菌RCEF091056的最佳组合为麦芽糖4%、酵母粉1.5%、MgSO4 0.3%、发酵时间48 h。纳豆提取物质在pH68有较好的酸碱稳定性,在80℃以下都有良好的热稳定性。Zn2＋、Cu2＋、Fe3＋和Ca2＋对抑菌物质抑菌效果有较大的影响。表明纳豆提取物对金黄色葡萄球菌和大肠杆菌有一定的抑制作用,纳豆提取物的稳定性较强。

Effect of Commercial Cellulase Enzymes on Ethanol Production from Pretreated Rice Straw at High Solid Loading

Effect of commercial cellulose enzymes was investigated by batch enzymatic hydrolysis at 15.0% （w/v） solid. It was found that the best commercial cellulose enzyme was Cellic（R） CTec comparing to Accellerase 1000TM and Accelerase 1500TM. The Cellic（R） CTec gave the highest reducing sugar concentration and rice straw conversion. Moreover, when the hydrolysate obtained from hydrolysis using Cellic（R） CTec was fermented by Saccharomyces cerevisiae TISTR 5596, it would give the highest ethanol. In this study, the Cellic（R） CTec was used for fed-batch prehydrolysis prior to ethanol production by simultaneous saccharification and fermentation （SSF） way at 20% （w/v） solid loading. It could produce 35.76 g/L or 4.6% （v/v） of ethanol concentration and 83.67 L/ton dry matter （DM） of yield.