Isolation and Identification of Specific Spoilage Organisms in Crayfish(Procambarus clarkii)before and after Processing

In order to explore the suitable sterilizing process,the main types of specific spoilage organisms in crayfish before and after processing were investigated. The spoilage bacteria were isolated from unprocessed raw crayfish and marinated ready-to-eat crayfish by using traditional plate separation method. The bacteria species were initially classified by colony morphological observation and Gram staining. Then 16S rDNA PCR,restriction endonuclease digestion analysis and 16S rDNA sequencing were performed to identify the screened bacteria. The specific spoilage organisms from raw crayfish were determined to be Macrococcus caseolyticus,Aeromonas hydrophilic,Enterobacter cloacae,Exiguobacterium indicum and Bacillus spp. Compared with raw crayfish,only Bacillus spp. including Bacillus cereus and Bacillus thuringiensis were detected in ready-to-eat crayfish,as other types of spoilage organisms were killed after marinating operation. The results showed that Bacillus spp. still survived in ready-to-eat crayfish after processing,thus causing corruption.