Biochemical and PCR Assay for Detection of Pathogenic Bacteria in Shrimp and Shrimp Farms

Abstract

The study was conducted to detect faecal coliforms and pathogenic bacteria in shrimp and shrimp farms. A multiplex PCR system was used for the rapid detection of pathogenic Aeromonas sp., Clostradium sp., Listeria sp., Salmonella sp., Shigella sp., Vibrio sp. and Staphylococcus sp. in the water, sediment and shrimp. The target genes chosen for this investigation were Aer gene for Aeromonas sp., hilA gene for Salmonella sp., virA gene for Vibrio sp., Sec gene for Staphylococcus aureus, neurotoxin gene type A,B,E,F for Clostridium botulinum, internalin gene for Listera sp. and ipaH gene for Shigella sp. respectively. Seven pairs of specific primers were used to amplify internal fragments of the genes by PCR. The PCR products were then analyzed and confirmed with relative ease by gel electrophoresis. Aeromonas and Vibrio sp. were found in the water, sediment as well as in the shrimp being the dominant bacteria. On the other hand, Salmonella and Clostridium were found in the sediment of one sample but there was no evidence of Listeria, Staphylococcus and Shigella in the farms. All samples contained relatively large number (1100 to ≥2400 mpn/gm) of coliform bacteria. The result revealed that the PCR-based rapid detection system could be a powerful method for routine monitoring and risk assessment of water quality in the shrimp farms.