The Study and Identification of Bacterial Spoilage Species Isolated from Catfish during Refrigerated Storage

Abstract

Catfish farming is relatively new in the state of Delaware although it has been a long standing profitable business in the southern United States. Catfish fillets used in this study were stored at 4°C for 1-2 weeks, after which, bacterial growth was expected on the surface of the fish. Bacteria were isolated and cultured on selective and differential media. Bacterial growth curves formulated from results in this study can be used to assess the shelf-life of catfish fillets under refrigerated storage. A specific spoilage organism was targeted to further understand and prevent microbial degradation of catfish fillets. The need for target gene 16S to be used for the discrimination of Pseudomonas spp. was confirmed rather than target gene rpoD; as it does not discriminate sufficiently to permit resolution of Pseudomonas spp. intrageneric relationships. Pseudomonas spp., Shewanella spp., Bacillus spp., Myroides spp., Aeromonas spp., and Enterobacter spp. were found to be contributors to the spoilage of catfish in the state of Delaware through method of 16S rDNA sequencing. The comparison of spoilage rates from both retail purchased and pond obtained catfish fillets illustrated need for increased catfish farming and production for sustainability in the State of Delaware.