Rearch On The Functional Characterization Of Soybean Meal Fermented By Lactic Acid Bacteria

Soybean meal is an important protein source for livestock and poultry. Lactic acid fermentation can eliminate the antinutritional factors and improve nutritive value of soybean meal. However, most of studies have been studied the effect of lactic acid bacteria from other source on fermentation of soybean meal. No study has separated lactic acid bacteria from fermented soybean meal. Now, firstly, we isolated lactic acid bacterias from fermented soybean meal, and continued to screened a strain of lactic acid bacterias by UV mutagenesis. Secondly, we studied the parameters of solid state fermentaion, the changes of compositions in soybean meal during the fermentation, the isolation and purification of antioxidant peptides from the biological soybean meal. Thirdly, effect of fermented soybean meal on blood antioxidant indices, gastrointestinal digestive enzyme activities and bacteria flora in mice, on growth performance, nutrient digestibility and blood indices in piglets were studied. Therefore, we provide a theoretical basis and technical basis for that soybean meal was fermented for young animals.1. Screen of lactic acid bacteria strains for fermented soybean meal and study of the parameters for fermentationIn order to obtain a lactic acid bacteria for preparation of fermentd soybean meal, the paper used conventional microbiological techniques.Firstly, we separated lactic acid bacterias from fermented soybean meal, and continued to screen a strain of lactic acid bacterias by UV mutagenesis.Then, We obtained the best parameters of fermentation are3%inoculum volume,40%of moisture contents,0.15%protease addition, and natural PH through one factor and orthogonal design desigen experiment.2. Changes of compositions in fermented soybean meal during lactic acid fermentationSoybean meal was fermented by L.plantarum B and the changes of some components in fermentdd soybean meal were studied during the fermentation. Lactic acid fermeantion can increase the digestibility of protein in fermented soybean meal in vitro.The high molecule weight proteins were degraded into small peptides. L.plantarum B fermentation can decrease the content of total sugars, increase the content of reductive sugars too, meanwhile, the content of oligosaccharide also decreased.The content of trypsin inhibitior, urease and soybean antigen decreased, but little phytate was degraded. Isolation and purification of antioxidant peptides from fermented soybean meal by ultrafiltration and gel filtration chromatography was done in order to realize both the antioxidant activity of peptides and its composition. Antioxidant activity and amino acid composition were analyzed using methods containing laboratory analysis and experiments in vitro. The results showed that all different fractioned peptides had scavenging effects on radicals. In these peptides, peptide P3has the strong inhibitory activity. These results showed that peptide P3had the good antioxidant activity.3. Effect of fermented soybean meal on blood antioxidant indices, gastrointestinal digestive enzyme activities and bacteria flora in miceThe experiment was conducted to study the effect of fermented soybean meal on blood antioxidant indices, gastrointestinal digestive enzymes levels and bacteria flora in mice. Forty-five Kunming male mice (BW=15.66±1.26g) were randomly assigned to3treatment groups with3replicates and five mice in each replicate. The control group was fed basal diet with normal soybean meal. In treatment1and treatment2, soybean meals were replaced by50%and100%fermented soybean meal respectively. The results showed that fermented soybean meal significantly increased stomach protein enzyme activities (P<0.01), decreased Escherichia Coli counts (P<0.05). Counts of bifidobacterium in treatment1and treatment2were increased by5.54%(P<0.01) and3.30%(P<0.05), MDA level were decreased by18.15%(P<0.05) and22.12%(P<0.01) compared with control group respectively. Organic indices of liver, spleen and kidney of treatment1were higer than that of control group (P<0.05),In conclusion, fermented soybean meal could increase blood antioxidant ability, gastrointestinal digestive enzyme activities, intestinal flora amounts and immune organic indices, so that fermented soybean meal is suitable to young animals.4. Effect of fermented soybean meal on growth performance, nutrient digestibility and blood indices in pigletsThe experiment was conducted to study effect of fermented soybean meal on growth performance, nutrient digestibility and blood indices in piglets. Thirty-six piglets with average body weight of (9.62±0.72) kg were randomly allotted to3groups on the basis of litter and weight, and3replicates per group and4piglets per replicate. The control group was fed basal diet with normal soybean meal, and group Ⅰ and group Ⅱ were fed basal diet in which50%,100%soybean meal were replaced with biological soybean meal.Serum was collected at21d age for blood parameter measurement and faeces of piglets were collected during a period of3consecutive days between18d to20d for digestibilitymeasurement. Piglets were slaughtered to measure morphology of small intestine. Results showed that piglets in group Ⅰ and Ⅱ both had a significantly increase in average daily gain (ADG)(P<0.05), and both had a significantly reduction in diarrhea ratio (P<0.01) compared with control group. Fermented soybean meal significantly increases the coefficients of total tract apparent digestibility (CTTAD) of dry matter, protein and organic matter (P<0.05). The level of alkaline phosphates and total protein in serum of group Ⅱ both higher than that of control group (P<0.05).The level of blood albumin in serum in group Ⅰ and group Ⅱ were both higher than that of control group (P<0.05), and level of blood urea of group Ⅰ and group Ⅱ decreased (P<0.05) and significantly decreased (P<0.01) respectively. The levels of MDA and IgG in group Ⅰ and group Ⅱ were both lower than that of control group (P<0.05) respectively. The results of the correlation analysis showed that the average daily gain of the piglet had positive correlations with level of ALP, TP, ALB, SOD and T-AOC (R2=0.6321、0.7795、0.9842、0.9951、0.9477),and had negative correlations with level of BUN and MDA in blood (R2=0.9825、0.9964). In conclusion, fermented soybean meal is beneficial to growth performance, apparent digestibility of nutrient, blood indices, and keep the integrality of small intestine morphology, improve the immunity and antioxidation activity in piglets.