Isolation and Characterization a New Bacteriophage Infecting Fish Pathogenic Aeromonas hydrophila

Abstract

The aquaculture industry is suffering from severe losses due to Aeromonas infection. Due to recent increase in the multidrug resistance (MDR) Aeromonas Sp. ineffectiveness of different treatment methods scientist are exploring more biological control methods. Bacteriophage are promising candidate in this regard as they can even kill MDR bacteria with almost no negative effects towards the environment and organism The present study was designed to isolate and characterize the lytic bacteriophage, and to determine its protective effect against the Aeromonas infection in Loach fish Water and soil samples were collected from different location of Korea. Phage isolation was performed by the enrichment method. It was characterized by TEM, one step growth curve, ph and temperature stability. Next generation sequencing (NGS) was performed for genome analysis. We isolated a phage Akh-2 from, Korea, found to inhibit the growth of 4 out of 8 tested A. hydrophila strains. TEM result showed that Akh-2 most probably belongs to the Siphoviridae family, having the head and tail size 50 ±5 nm and 170 ±5 nm, respectively. One- step growth curve of phage Akh-2 showed that it has a latent period of 50 ±5 minutes and with a burst size of 139 ±5 PFU per infected cell. The phage is stable in pH range from 6 to 8 and the temperature range from -80 oC to 46 oC. NGS data confirms that the size of genome is about 114901bp with G + C content of 44.22 % and 254 open reading frames. The Loach that received phage therapy had shown increase in survival rate and delayed mean death time when compared to the control.

Keywords: Aeromonas hydrophila, Phage, Disease, Biocontrol