The Screen And Fermentation Research Of The Swine Probiotic Bacillus

With the emergence of resistance, toxic residues and environmental issues causedby the abuse of antibiotic, looking for non-toxic alternatives is imminent. Probiotics isa biological product which could improve intestinal microflora balance and play a rolein Animal gut. Bacillus is one of a probiotics, which can form endospores, resistant toacid, high temperature, etc.In this study, remarkable probiotic properties, especially the ability of adhering tointestinal mucus and antibacterial properties, have been discovered in the probioticstrains of B. cereus BC158, then its high-density culture technology was optimized, thespecific findings are as follows:1、After spore staining and gram staining, a total of three colonies exhibitingdifferent morphologies were picked up isolated from the faeces of healthy piglets(15-40days),which could antagonize common intestinal pathogens(Escherichia coli08,Salmonella enteritidis and Staphylococcus aureus), combined the results of the16SrDNA molecular and biochemical analysis, BC158, BC234, BC236were identifiedas B.cereus.2、Asssays were further performed on the3isolates(BC158、BC234、BC236)to examine the essential characteristics and security features as potential probiotics,The results in this study indicated that the BC158has potential probioticcharacteristics, especially it shows strong adhesion activity and inhibition activityagainst pathogen strains, which exhibit promising application in aquaculture. Resultsshowed that the adhesion activity of BC158to Dacron was stronger, adhesion rates toforegut mucus, midgut mucus and hindgut mucus were39.68%,33.49%and33.25respectively. BC158was tolerant to0.9%bile salts and able to resist to pH2for2hwithout much loss of viability. Importantly, it was susceptible to all of the antibioticstested and could also produce amylase, proteas and cellulase. Meanwhile, it was Bacillus cereus enterotoxin (BCET) negative. it can also improves the growthperformance and stimulates the development of immune organs in mice. then theanimal experiments were carried out on the BC158to examine its effect on the mice,during the three weeks of feeding, the mice grew well in the test group, no diarrheaand vomiting occurred, and at the same time it has a greater impact on the growthperformance of mice, such as their average daily gain increased significantly, feedconversion decreased also, and had not seen any gastrointestinal lesions in the processof dissecting, Meanwhile, the thymus and spleen index of mice increased significantlycompared with the control group, it indicated that Bacillus cereus BC158couldstimulate the development of immune organs in mice.3、The growth characteristics and fermentation medium of BC158were studied.Optimum fermentation conditions were: temperature:37℃, pH:7.2, shake speed:180r/min, incubation time:18h. Optimize the best ratio experimentally derived istheCombined the single factor experiment and response surface, the optimumfermentation medium was obtained: dextrin12.40g/L, corn syrup35.77g/L, NaCl2.03g/L, under this condition, the viable cells of Bacillus cereus BC158was5.89×109cfu/mL, after the proven test, the actual number of viable cells was5.21×109cfu/mL, it was very close to the predicted value, it indicated that the model wascredible.