复合生态菌固态发酵木薯渣工艺参数优化及混菌发酵对木薯渣营养品质的影响

Solid-state Fermentation Parameters Optimization and Nutritional Improvement of Cassava Residue with Complex Culture of Microbial Strains

本试验旨在探讨复合微生物固态发酵木薯渣最佳发酵参数,并考察混菌发酵对木薯渣营养品质的影响。从木霉、曲霉、枯草芽孢杆菌和酵母4大类共12株菌中分别筛选出1株发酵效果较好的菌株,以营养改善最佳的菌株为主发酵菌,与其它3株进行不同组合,筛选出最适发酵组合,并考察组合中不同菌种最适接种比例、接种量和菜粕添加量;在此基础上采用正交试验设计,考察发酵时间、发酵温度、料水比以及初始p H间交互作用对木薯渣营养价值的影响。结果表明:每克发酵原料按黑曲霉-II∶枯草芽孢杆菌-II∶酿酒酵母=3∶2∶1的比例接种2.5×106个微生物(孢子),菜粕添加量为20%,发酵时间4 d,发酵温度35℃,料水比1∶2,初始p H 4效果最好。以最优条件发酵木薯渣,以干物质计算,发酵后木薯渣粗蛋白由10.77%提高到17.92%(P<0.05),粗纤维由21.50%降低到16.54%(P<0.05)。此外,发酵后产物羧甲基纤维素酶、滤纸酶、β-葡萄糖苷酶酶活分别达到12.31、3.92和3.95 U/g DM。利用复合微生物固态发酵可以显著提高非常规饲料原料木薯渣的营养价值。

This experiment was conducted to investigate the nutritional improvement of cassava residue by solid-state fermentation（SSF） using complex microbial strains and the optimal fermentation parameters were investigated. Four single microbial strains（Aspergillus Niger-II, Trichoderma viride, Bacillus subtilis-II and Saccharomyces cerevisiae）with best fermentation effect were screened from 12 strains and the strain with best nutritional improvement was selected as the main strain to formulation with other three strains screened for SSF, also the strains inoculation proportion, inoculation size and the ratio of rapeseed meal to cassava residue were optimized. Orthogonal experiment design was further used to optimize the fermentation parameters such as time, temperature, moisture and initial p H on nutritional improvement of cassava residue. The results showed that inoculateing 2.5 ×106germ per gram fermentation materials with Aspergillus Niger 2： Bacillus subtilis 1： Saccharomyces cerevisiae at the ratio of 3：2：1, adding 20%rapeseed meal（rapeseed meal： cassava residue ratio）, controlled the ratio of substrate vs water to 1：2 and fermented with initial p H 4 at 35℃ for 4 days got a best nutritional improvement of cassava residue. Fermenting cassava residue under the optimized condition and calculated base on dry matter, crude protein was increased from 10.77% to 17.92%（P〈0.05） and the crude fiber was significantly decreased from 21.50% to 16.54（ P〈0.05）. Moreover, the enzyme activity of CMCase, FPA and β-Glucosidase reached to 12.31, 3.92 and 3.95 per gram dry matter after SSF,respectively. Our results suggested that the SSF with mixed microbial strains offers a better nutritional improvement of none-conventional feed resources such as cassava residue.