Characterization of Vibrio alginolyticus bacteriophage recovered from shrimp ponds in south west of Iran

Farming of the pacific whiteleg shrimp (Litopenaeus vannamei), consists the greatest percent of aquaculture production of crustaceans all over the world. Vibriosis caused by Vibrio species such as Vibrio alginolyticus, is a serious limiting agent for aquaculture. Phage therapy is an eco-friendly alternative to antibiotics as a prophylactic measure for the growth of pathogenic bacteria. The aim of this study was isolation and characterization of Vibriophages present in L. vannamei breeding and culture facilities and estuarine resources in south west of Iran, Choebdeh shrimp farming site of Abadan city, Khuzestan Province, based on morphological structure, biological conditions and their potential applications in lysis of Vibrio bacteria. The bacterial and phage samples were analyzed using different physicochemical parameters, 16S rRNA gene sequencing and TEM. The results showed the V. alginolyticus isolates and identified the Podoviridae family of phages. These bacterial isolates were resistant to ampicillin and penicillin. The efficacy of the Podoviridae phage against V. alginolyticus bacterium indicated that this phage has a short period of 30 minutes latent phase, possessed a desirable stability and growth in keeping for 1 hour at 30-55oC, the salinity of 0.5-10 and pH of 5-8. Based on evaluation of phage therapy, mean absorbance values (OD600), in control and treatment groups, at 12 and 24 hours after phage inoculation, were significantly different (p<0.05). According to the results, phage therapy with singlephage suspensions did not prevent bacterial regrowth after treatment. However, delay in development of resistance is a desirable success.