Milt-strains Liquid-state Seed-fermentation Of Soybean Meal And Solid-state Fermentation Of Brewers’ Spent Grains For Preparation Of Biological Feedstuff

The output of brewers’spent grains and soybean meal in China are more than 30 million tons annually. Brewers’spent grains and soybean meal deep fermentation can improve its feeding effectiveness, and it is also an effective way to solve the problem of shortage of protein source. Brewers’spent grains contain 35%-51%(dry medium) of crude protein, it’s a good source of dietary protein.At present, the research on the fermentation of brewers’spent grains protein feed products is relatively weak. With rich nutrition, soybean meal is suitable for microbial growth and it’s a good liquid seed culture for protein preparation fermented from brewers’spent grains. Relevant research is inadequate.So this article has a good theoretical and practical value.The method of Candida tropicalis and Bacillus subtilis mixed fermentation were used in this paper for the study of liquid seed production technology. Different frequency ultrasound effecting growth basic rule of mixed bacteria were investigated. The milt-strains liquid culture and fermentation conditions of producing high quality protein feedstuff from brewer’s spent grain were also studied. The research work and conclusions are as follows:For the needs of high-performance bio-feed prepared by solid-state fermentation of soybean meal, The method of Candida tropicalis and Bacillus subtilis mixed fermentation were used in this paper for the study of liquid seed production technology.The culture conditions and medium composition of producing large number of multi-strains from liquid seed culture medium were studied by a serial of single factors and orthogonal design tests. Results showed that the optimal conditions were:the glucose content of 1%,the soybean meal content of 15% and initial pH 9.0,inoculation amount of 10% from liquid seed,culture time of 5d,temperature 28℃, Candida tropicalis and Bacillus subtilis bacteria can reach the largest amount.The number of Bacillus subtilis is 267.2×107 cuf/ml and Candida tropicalis is 715.5 X 106 cuf/ml.In this paper, ultrasound effecting growth basic rule of mixed culture was investigated. We can see the appropriate frequency and sound intensity of ultrasound on cell have some role in promoting growth, when more than a certain limit, the ultrasound will destroy microbial cells. In sound intensity for the 0.14 W/cm3,24 kHz, 28 kHz,33 kHz and 40 kHz ultrasonic have a role in promoting the growth of two bacteria with certain time and culture days.But 68 kHz ultrasonic frequency began to have inhibition on the growth of bacteria.The fermentation conditions of producing high quality protein feedstuff from brewer’s spent grain were studied by a serial of single factors and orthogonal design tests. Results showed that the optimal conditions were:the proportion of brewer’s grains and soybean meal was 7:3, inoculum amount was 20%, the addition amount of ammonium sulfate was 0.5%, the addition amount of urea was 0.5% fermentation time was 2 d. Under optimized conditions, the protein content was increased to 39.13%.