Detection of invA gene of Salmonella from milkfish (Chanos chanos) at Sidoarjo wet fish market, Indonesia, using polymerase chain reaction technique

Abstract

Aim: The study aimed to detect the invA gene in Salmonella isolated from milkfish in the Sidoarjo wet fish market. Materials and Methods: A total of 84 samples were prepared in enrichment media and isolated on the surface of Salmonella Shigella Agar. Salmonella growth produces transparent colonies with blackish color in the middle due to H2S gas formation. Samples were identified as Salmonella based on macroscopic colony morphology. Presumptive Salmonella sp. was put on Bismuth Sulfite Agar media. Salmonella was determined based on the results of the biochemical test that has been carried out using Microbact identification kits from negative gram staining. Results: The results of this study indicate that 32 of 84 samples (38.09%) were Salmonella bacteria. Furthermore, the invA gene detection was carried out using the polymerase chain reaction technique. Electrophoresis results showed four positive samples contained invA gene with a length of 284 bp. Conclusion: Results in this study indicate that contamination of milkfish with Salmonella needs strict hygienic measures to prevent their transmission to human.