Research On Biological Characteristics,Fermentation Process And Spray Drying Process Of Pediococcus Acidilactici S204

The long-term use of feeding antibiotics has caused many problems.Many countries have already limited the use of antibiotics in feed additives.In this context,probiotics that have no residual pollution,non-toxic side effects and does not produce the advantage of resistance have received extensive attention.Probiotics have an important role in maintaining the balance of the intestinal microflora,helping the digestion and absorption of nutrients,inhibiting the growth of pathogenic bacteria,which are important for maintaining the health of hosts.Pediococcus acidilactici is an intestinal probiotic with probiotic effects.The use of P.acidilactici instead of antibiotics is of great significance to the sustainable development of husbandry.But the loss of living probiotic cell numbers during storage and gastrointestinal digestion is a challenge,which limited its application in industry and its beneficial effects to host and has to be overcome.Based on colonial morphology and the analysis of 16S rRNA,a strain isolated from powder was identified as P.acidilactici,and was named as Pediococcus acidilactici S204.The probiotic properties of P.acidilactici S204 were studied by testing its inhibition activity and the tolerance to high temperature,acid,bile salt and antibiotics.The results showed that the strain was able to inhibit the growth of E.coli and Staphylococcus aureus.It was resistant to the temperature of 55?,but the survival rate declined significantly at60? and above,the number of viable cells was 0 at 55? for 20 min.It had a survival rate of 66.17%at 1 h and 17.95%at 2 h treated with the simulated gastric juice of pH2.5.The strain was proved to have a good tolerance to the bile salt concentration of 0.1%to0.5%.It showed resistance to ampicillin,norfloxacin,ofloxacin,ciprofloxacin and vancomycin,while sensitivity to penicillin.The culture medium and fermentation conditions were optimized by Single Factor Test.The results showed that the best compositions of fermentation medium were 6%of glucose,6%of yeast extract,0.02%of MnSO₄·H₂O,0.04%of MgSO₄·7H₂O,0.5%of sodium acetate,0.2%of ammonium citrate,0.2%of K₂HPO₄ and 0.1%of Tween-80.Fermentation conditions:the pHof the medium was 6.5,the best fermentation inoculum was 5%,incubation temperature at 37? for 15 h.The biomass of P.acidilactici in such conditions reached 7.9×10⁹ cfu/mL.The scale-up experiment was further carried out in a5 L fermentor,the density of P.acidilactici could reached 2.7×10¹00 cfu/mL after 15 h.Single-factor experiments were used to optimize the spray drying process of P.acidilactici S204.The composition of the compounded wall material was 12%?w/v?reconstituted skim milk powder and 2%lactose.The inlet and outlet air temperature used were 160? and 63-68?,the viable count of lactic acid bacteria in microcapsules was3.83×10⁹cfu/g,and the survival rate was 67.06%.