Use Bacillus subtilis E20 and Saccharomyces cerevisiae P13 to co-fermentation for decrease fermented defatted soybean meal viscosity in Asian seabass (Lates calcarifer) feed

• Main Authors: Fu, Hsin-I, 傅馨儀
• Other Authors: Chiu, Chiu-Shia
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/50454883125319334543

碩士 === 國立屏東科技大學 === 食品科學系所 === 104 === The research of using fermented soybean meal (FSBM) to replace fish meal in aqua feed gradually becomes an important task. Bacillus subtilis was considerate a probiotics strain in aquaculture. However B. subtilis E20 produce γ-glutamic acid during fermentation, leaded to high viscous material which mught increase cost of FSBM. In this study, the experimental design was used to optimize the process of B. subtilis E20 and S. cerevisiae P13 co-fermentation in defatted soybean meal. First evaluate the inoculation time of two strains in fermented defatted soybean meal. It was found both B. subtilis E20 and S. cerevisiae P13 can growth in fermentation defatted soybean meal when inoculum S. cerevisiae P13 after inoculum B. subtilis E20 to fermented defatted soybean meal 8 hours in 37℃. Plackett-Burman design (PBD) was employed for screening parameters for produce high B. subtilis E20 and S. cerevisiae P13 content and low viscosity in co-fermented defatted soybean meal. The initial moisture of defatted soybean meal, fermented temperature and times of S. cerevisiae P13 inoculation after B. subtilis E20 inoculation. The Box-Behnken design (BBD) and response surface methodology (RSM) analysis was then adopted to derive a statistical model for optimizing the conditions of defatted soybean meal fermentation with lower viscosity by B. subtilis E20 and S. cerevisiae P13. The experimental results showed that the optimum fermented condition for high strains content and low viscosity of fermented defatted soybean meal were 35% initial moisture of defatted soybean meal, 37℃ of fermentation temperature and S. cerevisiae P13 inoculation post 14 h of B. subtilis E20 inoculation. Under the optimal condition, the enumeration of viable B. subtilis E20 and S. cerevisiae P13 in fermented defatted soybean meal were 9.10 and 7.71 Log CFU g-1 respectively, and the viscosity and γ-glutamic acid of fermented defatted soybean meal were 0.208 cP and 0.087 g g-1, which was lower than the viscosity and γ-glutamic acid of fermented defatted soybean meal by B. subtilis E20 (0.341 cP and 0.346 g g-1). Therefore, the optimal condition was applied for the production of low viscosity fermented defatted soybean meal to replace fish meal in diet of Asian seabass (Lates calcarifer). All experiment diet use for this study including control diet, replacing fish meal in Asian seabass diet by 15%、20% and 25% of unfermented defatted soybean meal and 20%, 25%, 30% and 35% of unsterilized or sterilized fermented defatted soybean meal. A total of 12 same protein and lipid content diet was used to feed Asian seabass for 2 months. The results showed that fermented defatted soybean meal without sterilization had lower substitution level of fish meal in diet, and lower survival than sterilized fermented defatted soybean meal due to cannibalism. Whereas, the feed efficiency of replacing fish meal at the level 35% in Asian seabass diet by sterilizing fermented defatted soybean meal was better significantly than replace fish meal at the level 20% by defatted soybean meal. The results of the present study indicated that using B. subtilis E20 and S. cerevisiae P13 to co-fermentation not only decrease the viscosity of defatted soybean meal but also can use sterilize fermented defatted soybean meal to replace fish meal at the level 35% in Asian seabass feed.