Study Of Biotransformation Of Soybean Isoflavone Based On Microbial Solid-state Fermentation

In this study, Bacillus subtilis ATCC6633,EM strains, and Lactobacillus planetarium ATCC8014was employed to screen the optimal strains for the transformation of the aglycone of soybean isoflavones by microbial solid-state fermentation. High performance liquid chromatography (HPLC) was used to detect the contents of soybean isoflavones. The feed has a double feature of nutritional and health. This can provide a theoretical for probiotic fermented feed production and application.The first part was aimed to screen the optimal strains. Bacillus subtilis ATCC6633,EM strains, and Lactobacillus planetarium ATCC8014was employed to screen the optimal strains for the fermentation (30℃,35%water content,6%inoculation level,7d culture time).The results demonstrated that the microbial single fermentation have higher biotransformation efficacy than that of microbial mixed fermentation. The ratio of aglycone in total soybean isoflavone content by Bacillus subtilis ATCC6633,EM strains was reached52.13%和64.56%. The samples fermentation had high repeatability and stability. To screen the optimal strains from Bacillus subtilis ATCC6633and EM strains. The two strains was employed through single and mixed fermentation. The results demonstrated that the ratio of aglycone in total soybean isoflavone content reached54.18%based on EM strain fermentation at7d. So, EM strain was the best fermentation strain.The second part:The biotransformation efficacy of soybean insoflavones was studied using EM strains and B. subtilis ATCC6633through single and mixed fermentation. In this work, the biotransformation efficacy of aglycone was investigated by high performance liquid chromatography (HPLC) analysis. The results demonstrated that the ratio of aglycone in total soybean isoflavone content reached54.18%based on EM strain fermentation at10d. This study can provide theoretical ground for the industrialization production using microbial fermentation.The third part:the study improving the biotransformation efficacy of soybean isoflavone was carried out by EM strains solid-state fermentation. The fermentation temperature (℃), water content (%), inoculation level (%), cuture time (d) and fineness of pulverization was selected as contributing factors based on the orthogonal design. The results showed the optimal fermentation conditions were40℃,35%water content,7%inoculation level,15d cuture time and40of fineness of pulverization, respectively. The biotransformation efficacy of soybean isoflavone was the highest based on the optimal fermentation conditions. The ratio of aglycone in total soybean isoflavone content reached85.3%, respectively. The third part was aimed to study the influence of fermentation process parameters to the quality of Soybean meal. The second part of research confirmed the high conversion rate of treatment group. Based on that, detected the total number of microorganisms, lactic acid bacteria, lactic acid content, antioxidant activity and protein content and pH value, etc. The results showed the lactic acid content was8.62±.57g/kg, the protein content was45.54±3.98%, the scavenging activity to DPPH was76.13±2.37%. Relative to the not fermented soybean meal, all the index were significantly improved. It proved that the activity of soybean isoflavones was improved and other good quality of feed was remained.The study showed that the soybean meal with high activity of soybean isoflavones has a double feature of nutritional and health. At the same time that some advantages including simple and operational fermentation process, most important of that production process have no waste water and waste discharges, and the product can significantly improve a feed utilization. This study provide a method that non-conventional feed are utilized effectivly while producing safety and high-quality livestock products, which has good development prospects.