Combined Inactivation And Genomic Analysis Of Lactobacillus Plantarum Virulent Bacteriophage

Lactobacilli are often used as starter cultures in dairy industry,their growth and metabolic activity express significant impact on the quality of products.However,in the process of fermentation,phage infection often cause fermentation failure.In this study,the host spectrum of Lactobacillus plantarum virulent phages P1 and P2 were evaluated.Moreover,the inactivation effects of 0.3% peracetic acid combined with other chemical reagents(ethanol,isopropanol,sodium hypochlorite,chlorine dioxide)were studied.Meanwhile,the internal relationship between phage genetic properties and inactivation effect was tried to explicate.The results showed that:(1)Three of 62 Lactobacillus plantarum strains were found to be sensitive to phage P1 and nine strains to phage P2.(2)100% ethanol treated for 5 min,followed by 5 min treatment of 0.3%peracetic acid could produce higher inactivation effect on phage P1 and P2,with 3.38 and 2.70 log reduction,respectively.(3)For phage P2,100% isopropanol treated for 5min followed by 0.3%peracetic acid treatment for 5 min can result in 2.9 log reduction.(4)Mixed 0.3% pracetic acid and 800 ppm sodium hypochlorites together can completely inactivate phage P1 in 10 min.For phage P2,treatment of 800 ppm sodium hypochlorite for 5 minutes followed by 0.3% peroxyacetic acid for 5 minutes can cause 5.05 log reduction.(5)For phage P1 and P2,300mg/L chlorine dioxide treated for 5min,followed by 5 min treatment can result in 4.99 and 6.75 log reduction,respectively.(6)The genome size of phage P1 was 73.79 KB,GC content was 39.12%,which encoded 86 CDS and 2 t RNA.Through comparative genomic analysis,it was found that the proteins related to the synthesis of tail proteins in phage were related to the inactivation effect of sodium hypochlorite,proteins associated with the synthesis of capsid proteins were associated with the inactivation effect of alcohols and peracetic acid.