Breeding Of Feed Probiotics And Studies On Its Culture Conditions

15Bacillus strains were isolated from the dejecta of the healthy piglets. From the strains we selected a strain of bacillus named B8which has a strong inhibitory effect on the intestinal pathogenic bacteria in porcine enteric, further research indicated that the strain possess tolerance to the gastric acid, bile, heat, whatsmore it can produce enzyme of high activity. The results of the i dentification and the study of culture conditions were as follows:(1) Isolation and screening of feed probiotics:Through primary and secondary screening,15Bacillus with good antibacterial activity was separated, respectively numbering them for B1、B2、B3...B15.(2)The studies on probiotic characteristics of feeding probiotics:The bacillus B8has a strong inhibitory effect on the intestinal pathogenic bacteria of pig gut such as E. coli, Salmonella, Staphylococcus aureus, The diameter of antibacterial circle is respectively19.42,17.31,19.85; In the study of stress resistance, when strain B8was heated in water at90℃for10min, the survival rate reached86%, so it has a good property of heat resistance; In the research of resistance to gastric and intestinal juice of human,when cultured the strain B8in the gastric juice of pH2, the survival rate can reached81.2%,and when the gastric juice was replaced by0.3%intestinal juice the survival rate can also reached82.9%after3h,so the;we can find that the strain B8has a surprising production of protease and amylase activity during our study.(3) Identification of feed probiotics:we have studied the morphological characteristics as well as physiological and biochemical characteristics of the strain B8, based on our result together with the the reference of "Berger’s Manual of determinative bacteriology"and "Common bacterial System Identification Manual", the strain B8is preliminarily identified as Bacillus subtilis.(4) The studies on the best culture conditions of feed probiotics:In our study of the liquid culture of B8, we find out that the optimum culture conditions:Inoculating age is15h, culture temperature is34℃, rotation rate is180r/min, amount of inoculum is7%, inoculum volume is30%, initial pH value is7.5, In addition, we have studied the growth cycle of the strain and drawn the growth curve of B8to explore the regular pattern of growth.We found that the strain B8has typical growth regularity including lag phase logarithmic phase, stable phase,decline phase,the lag phase is0～6h, the logarithmic phase6～15h, the stable phase is15～30h,after then they came into the decline phase. In oue study very small amount of spore was produced in the logarithmic phase,while in the stable phase of15～21h,spore began to form to a large number,during the21～30h,the number of spore is relatively stable,the number of spores was reduced at30h.