Screening And Identification Of Enterococcus Faecium And Its Microencapsulated Formulation Study Including Perpartation And Efficacy Assessment In Vitro

The aim of the study was to develop two kinds of high activity liquid and solid microencapsulated microbial ecological agents.Four new strains of Enterococcus Faecium with trusting biological characteristics were screened and identified.One of the strains was microencapsulated with microencapsulation technology before fermentation. Two kinds of microbial ecological agents,that were liquid and soild Microencapsulated Enterococcus Faecium by optimizing the technology were obtained and evaluated in vitro test method.The results as follows:Four new strains of Enterococcus Faecium were screened from healthy infant feces, piglet intestine and feces in the EC medium which were named as EtB,Ef1-2,Ef3-4 and Ef4-1.They were all identified as Enterococcus Faecium by Biolog automatic micro-analysis system.Comparing with their 16S rRNA GenBanks which indicated that there were 99%homology with Enterococcus Faecium strain SF（Accession No. AY675247）.The results of the two different identification methods were consistent.Their biological characteristics were studied which showed that all of them had fast growth rate. They were in logarithmic phase from 4h to 14h,entered stationary phase from 14h to 18h and declined after 18h.All of them could significantly inhibit the growth of Escherichia coli K88,Staphylococcus Aureus,Pasteurellosis Bacillus and Salmonella and the antibacterial circle diameter could be 10-15mm.They had the best antibacterial effect to Escherichia coli K99 and the antibacterial circle diameter reached 10-15mm.Enterococcus Faecium was encapsulated in calcium alginate using microencapsulation technology before fermentation and the living bacterial number was improved 2 orders of magnitude.The microcapsules of both moderate size and ideal morphology were got using 1.5%sodium alginate,30min hardening in 0.1mM CaCl₂. The particle size was 1200±76μm.We got solid microencapsulation with good color, uniform particles of 329μm by cultured in MRS including 0.2%anhydrous calcium chloride and dried for 5h under the condition of 45℃in electric blastdrying oven.When the inoculation amount reached 3%,yield improved 3 times and the living bacterial number was 11.06-1gCFU/g.The liquid microcapsules of Enterococcus Faecium and their characterstics were studied.The results indicated that liquid microencapsulated Enterococcus Faecium significantly inhibited the growth of Escherichia coli K88,Staphylococcus Aureus, Pasteurellosis Bacillus and Salmonella and the antibacterial circle diameter could be 12-15mm.They had the best antibacterial effect to Escherichia coli K99 and the antibacterial circle diameter reached 14.5mm.In comparison with free cultured,liquid microencapsulated Enterococcus Faecium demonstrated significant abilities in growth potential,resistence to high concentration of copper and simulating conditions of stomach（P＜0.01）.The experiment of storage at 4℃showed that there was no notablely decline as the number of live bacteria concerned.The characterstics of solid microencapsulated Enterococcus Faecium was studied. Studies using 80℃temperature and the artificial gastric and intestinal fluids which had shown that solid microencapsulated Enterococcus Faecium products could survive better than free Enterococcus Faecium products（P＜0.01）.The experiment of storage at room temperature showed that there was no notablely decline as the number of live bacteria concerned.Obviously,solid microencapsulated Enterococcus Faecium products have good characteristics of stress resistance which would provide premise for their industrialization in the future.Conclusion:Four new strains of Enterococcus Faecium with trusting biological characteristics were screened and identified.Two kinds of high activity liquid and solid microencapsulated Enterococcus Faecium products of Good color,moderate size,ideal morphology,good Resistance and stability were got using microencapsulation technology before fermentation.Therefore,the microencapulation can improved the rate of survival Enterococcus Faecium significantly under extreme conditions.This would be beneficial for the development of new microbial ecological agents with high activity that can be used widely in feedstuff.