Isolation and Characterization of some Bacteriophages and their Associated Bacteria in Sea Food: Phage-Host Interaction

Abstract

Abstract: Background: Economic loss due to diseases is a major problem in aquaculture. A number of bacterial illnesses may arise from the consumption of sea food that has been contaminated at source or during the processing. This study aims to isolate and characterize some bacteriophages specific for the most common sea food pathogens in addition to their associated bacteria. The work also extended to study the host-phage interaction and the potential use of phages as antibacterial agents to control sea food infecting pathogens. Materials and methods: Estimation of Vibrio spp and Aeromonas spp. in addition to their associated phages in different sources of sea food such as fish (Tilapia sp.), clam (Tapes decussatns) and crab (Callinectes sapidus) was carried out. Results: Crab exhibited the highest counts (200 CFU/g) of Vibrio spp., while the highest counts of Vibriophages (1500 PFU/g) were detected in clam. Fish harbored the highest counts (30 CFU/g) and (3000 PFU/g) of Aeromonas spp. and Aeromonas phages, respectively. Three different phages (VPS1, APS2 and APS3) in addition to the isolated bacteria were characterized. Results showed that VPS1, APS2 and APS3 were different, which was confirmed by molecular characterization using RAPD-PCR and the protein profile. APS3 was entrapped into calcium alginate beads and tested as antibacterial agent against Aeromonas hydrophila. Efficiency of APS3 was superior to the free particles (p<0.05) and realized 2.7 fold decrease in bacterial growth rate. Phage seeded beads were recycled for 7 successive cycles. Their activity was reduced up on reuse. Recommendations: This study revealed that phages remain an excellent potential tool for control of bacterial pathogens. Further research and manipulation of the isolated phages could produce novel effective biocontrol agents of sea food infectious diseases in marine aquaculture systems

Keywords

• bacteriophages; characterization; entrapment; phage-host interaction; antibacterial activity.