Isolation, Characterization, and Application of a Bacteriophage Infecting the Fish Pathogen Aeromonas hydrophila

Abstract

Bacteriophages are increasingly being used as biological control agents against pathogenic bacteria. In the present study, we isolate and characterize bacteriophage Akh-2 from Geoje Island, South Korea, to evaluate its utility in controlling motile Aeromonas septicemia. Akh-2 lysed four of the seven Aeromonas hydrophila strains tested. Transmission electron microscopy analysis showed that Akh-2 belongs to the Siphoviridae family, with head and tail sizes of 50 ± 5 and 170 ± 5 nm, respectively. One-step growth curve analysis revealed that the phage has a latent period of 50 ± 5 min and a burst size of 139 ± 5 plaque-forming units per infected cell. The phage appeared stable in a pH range of 6–8 and a temperature range of −80 to 46 °C. Based on next-generation sequencing analysis, its genome is 114,901 bp in size, with a 44.22% G + C content and 254 open reading frames. During an artificial induction of the disease, loach (Misgurnus anguillicaudatus) treated with Akh-2 showed an increased survival rate and time compared with the non-treated control. Our results suggest that Akh-2 is a potential biological agent for the treatment of Aeromonas infections in fish.

Evaluation of Novel Virulent Phages Infecting the Aeromonas Hydrophila and Escherichia coli Isolated from Sewage Water Samples

“…The lytic ability of ΦECP8 and ΦECP9 was not affected within a temperature range of 25-55°C, the infectivity of Aeromonas hydrophila phages ΦZH1 and ΦZH2 were highly sensitive to a temperature above 40°C (El-Araby et al, 2016) but in our results, the thermal stability of phage ΦAHP7 was sensitive to elevated temperature (55ºC to 70ºC) (Chen et al, 2018). In the same context, Akmal et al (2020) reported that Aeromonas phage Akh-2 retained its infectivity from -80°C to 37°C after three days of incubation.…”

“…ΦZH1 and ΦZH2 were classified in the family Podoviridae with strong virulence against Aeromonas hydrophila infecting Nile tilapia (El-Araby et al, 2016). Recently, Aeromonas phage Akh-2 was molecularly characterized and classified in the Siphoviridae family, phage Akh-2 was used as a therapy against Aeromonas infections in fish (Akmal et al, 2020).…”

A Hundred Years of Bacteriophages: Can Phages Replace Antibiotics in Agriculture and Aquaculture?

“…Phage treatment also proved effective against a variety of additional fish pathogens, with the administration by intramuscular injection of phages Φ2, and Φ5 (Myoviridae) achieving up to 100% survival in catfish (Pangasianodon hypophthalmus) infected with Motile Aeromonas Septicemia (MAS), caused by A. hydrophila; the survival rate was 18.3% in untreated fish [118]. A similar remarkable protective effect was achieved with the PAS-1 phage when used to combat the furunculosis caused by A. salmonicida in Rainbow trout (Oncorhynchus mykiss) [119]. In in vitro studies, the use of effective phage cocktails (AS-A, AS-D, AS-E) against this pathogen showed a faster control of bacterial concentration as well as a decrease in the frequency of occurrence of phage-resistant mutants.…”

Phages as a Cohesive Prophylactic and Therapeutic Approach in Aquaculture Systems

“…Infected (1 × 10 7 cfu/mL) loah treated by immersion in water containing 1.0 × 10 8 pfu/mL of single phage preparation Mortality rates were 16%, 53%, 57%, and 56.67% after 24, 48, 72, 96 h respectively when compared to the control group with 100% mortality; most of the surviving fish showed no disease symptoms [112] (2020) The maximum reduction in mortality varied from 29% to 92% for turbot and from 49% to 86% for Atlantic cod assessed during the experiment and depending on the strain used; notably, reduction in mortality was not significant in the majority of cases at the end of the experiment [113] Infected Senegalese sole juveniles were treated with single phage preparation After 72 h, infected fish juveniles treated with phages showed no mortality contrary to 36% mortality in the control group [101] (2016)…”