Isolation and identification of proteolytic spoilage bacteria in chilled pork

Quorum sensing ( QS) maybe affect the proteolytic activity of spoilage bacteria which plays an important role in chilled pork spoilage.Fifty-four proteolytic bacteria were isolated form chilled pork with skim milk agar.Forty-four gram-negative strains of those isolates showed AHLs production capability in AHLs evaluation assay using Agrobacterium tumefaciens PELR4 as a biosensor strain. The results of identification of 10 strains ( 5 strains for oxidase positive and 5 for oxidase negative respectively) from 44 isolates base on 16S rDNA showed that oxidasepositive isolates were Pseudomonas spp., while oxidase-negative isolates were Serratia spp. With analyzing the combined data of phenotypic characteristics and phylogenetic analyses of 16S rDNA and carA, PP103 and PP110 were identified as Pseudomonas lundensis. The tow strains can be used for the further study on the relationship between AHLs and protease expression of spoilage bacteria.