枯草芽孢杆菌发酵蔗渣生产黄腐酸的工艺条件优化

Optimum technical conditions of fermentation of bagasse for fulvic acid with Bacillus subtilis

对实验室筛选的发酵蔗渣产黄腐酸的4株(25B、BT、12、E)细菌进行工厂扩大发酵,并运用分子生物学方法对高产黄腐酸菌种进行鉴定.研究高产菌种的发酵周期、接种量、发酵培养基初始pH以及发酵堆料层等因素对菌种发酵蔗渣产黄腐酸的影响,利用正交实验方法优化发酵培养基的碳源添加与配比.实验结果表明,E菌株为发酵蔗渣高产黄腐酸的菌种,16SrDNA法鉴定结果为枯草芽孢杆菌.该菌种发酵蔗渣高产黄腐酸的最优条件为:接种菌龄24h,接种量0.05L·kg-1,发酵周期4d,发酵物料初始pH4.正交试验优化发酵培养基的主次顺序为蔗渣>麸皮>蔗糖>淀粉.利用优化后的发酵物料培养基与发酵条件进行发酵,获得的黄腐酸含量为23.90%,较工厂发酵模式的对照组(FA含量14.00%)提高9.90%,FA增长率为70.71%.

Basing on the enlarged fermentation of bagasse for fulvic acid （FA） with screened 4 strains bacteria,the high yield strain was sequenced and identified by 16S rDNA. Then the factors affecting the fulvic acid yield fermented with high yield strain,such as fermentation period,inoculum,the initial pH value of fermentation medium,the stacker layer and the ratio of carbon source added to the fermentation medium by orthogonal experimental design method were studied. The results showed that the production of fulvic acid fermented with E strain which was identified as Bacillus subtilis was the highest. The optimal fermentation conditions were： 4-day fermentation period,cell age 24 h,5 L·kg^-1 inoculum volum and the initial fermentation materials pH4. The optimum ratio of carbon source by orthogonal test showed that bagasse and wheat bran influenced the production of fulvic acid significantly. Applicated optimized fermentation conditions and medium,FA content fermented with E strain was 23. 90% ,which was enhanced 9. 90% compared with CK （FA content was 14. 00% ）,and the growth rate of FA was 70. 71% .