Ozone nanobubble treatments improve survivability of Nile tilapia (Oreochromis niloticus) challenged with a pathogenic multi‐drug‐resistant Aeromonas hydrophila
Abstract:A rapid increase in multi‐drug‐resistant (MDR) bacteria in aquaculture highlights the risk of production losses due to diseases and potential public health concerns. Previously, we reported that ozone nanobubbles (NB‐O3) were effective at reducing concentrations of pathogenic bacteria in water and modulating fish immunity against pathogens; however, multiple treatments with direct NB‐O3 exposures caused alterations to the gills of exposed fish. Here, we set up a modified recirculation system (MRS) assembled wi… Show more
“…[27] and Nile tilapia (Oreochromis niloticus) [28]. In the study of Al-Shammari et al [27], common carp had a high survival rate after the ozone treatment at 0.50 mg/ L. Nile tilapias were treated with ozone nanobubble at an ozone concentration of 0.14 mg/L with no mortality over a 14-day period [28].…”
Section: Discussionmentioning
confidence: 99%
“…Tis study suggests that direct ozone injection at a dose of 0.025 ppm could be sufcient to provide more than a 65% algae reduction in pond water. Te applied ozone concentration is likely not harmful to common carp [27] and Nile tilapia [28]. Additional studies are required to better understand the minimum concentration of ozone needed for algae control in earthen ponds.…”
Algal blooms can lead to low dissolved oxygen and fluctuating pH, and the toxins produced by some species can be toxic to aquatic animals. In this study, we assessed the potential of ozone nanobubble technology for reducing a diatom species, Nitzschia sp., commonly found in freshwater ponds in Hong Kong. This study suggests that ozone at a low dose of 0.025 ± 0.003 ppm was sufficient to reduce algae by 66.4% within 5 minutes of treatment. An even higher killing effect (68.2%) was observed when ozone was delivered using nanobubbles for 9 minutes. A 24-hour delayed effect was also detected, with a further reduction of approximately 10% of the algae for both ozone treatments (macro and nanobubble delivery methods). In addition to controlling algae, applying ozone at a level that is not detrimental to fish may also benefit the dissolved oxygen levels in pond systems.
“…[27] and Nile tilapia (Oreochromis niloticus) [28]. In the study of Al-Shammari et al [27], common carp had a high survival rate after the ozone treatment at 0.50 mg/ L. Nile tilapias were treated with ozone nanobubble at an ozone concentration of 0.14 mg/L with no mortality over a 14-day period [28].…”
Section: Discussionmentioning
confidence: 99%
“…Tis study suggests that direct ozone injection at a dose of 0.025 ppm could be sufcient to provide more than a 65% algae reduction in pond water. Te applied ozone concentration is likely not harmful to common carp [27] and Nile tilapia [28]. Additional studies are required to better understand the minimum concentration of ozone needed for algae control in earthen ponds.…”
Algal blooms can lead to low dissolved oxygen and fluctuating pH, and the toxins produced by some species can be toxic to aquatic animals. In this study, we assessed the potential of ozone nanobubble technology for reducing a diatom species, Nitzschia sp., commonly found in freshwater ponds in Hong Kong. This study suggests that ozone at a low dose of 0.025 ± 0.003 ppm was sufficient to reduce algae by 66.4% within 5 minutes of treatment. An even higher killing effect (68.2%) was observed when ozone was delivered using nanobubbles for 9 minutes. A 24-hour delayed effect was also detected, with a further reduction of approximately 10% of the algae for both ozone treatments (macro and nanobubble delivery methods). In addition to controlling algae, applying ozone at a level that is not detrimental to fish may also benefit the dissolved oxygen levels in pond systems.
“…The application of ozone for shellfish depuration [107] , removal of algal toxins [108] , the improvement of fish taste and odour [109] , and water colour elimination [110] have also been reported. More importantly, the overall enhancement of the water quality via disinfection against bacteria and viruses (including Aeromonas hydrophilia [111] , Vibrio parahaemolyticus [73] and Motile Aeromonas septicaemia [112] ) is well documented. However, for this to be achieved, higher ozone dosages are required to overcome the organic demand in water, for the sustenance of ozone concentration levels capable of significant bacterial and viral inactivation [105] .…”
Section: Industrial Applications Of Ozonementioning
confidence: 99%
“… Fig. 7 Recirculating aquacultural systems at different scales (a) large scale (adapted with permission from [119] ); (b) pilot-scale (adapted from [120] ); (c) laboratory scale (adapted with permission from [112] ), showing the application of ozone nanobubbles for increased ozone dissolution. …”
Section: Industrial Applications Of Ozonementioning
“…Sera were collected after centrifugation at 8,000 x g for 15 min, stored at -20 o C until used. ELISA assay was carried out following the protocol described by Dien et al (2021).…”
Section: Determination Of Serum Antibody By the Enzyme-linked Immunos...mentioning
Aeromonas hydrophila infection is considered one of the most important bacterial diseases responsible for the loss of millions of dollars in the global freshwater aquaculture industry. Multidrug-resistant (MDR) A. hydrophila is becoming a global issue of concern. Non-antibiotic approaches can minimize the requirement for antimicrobials to combat infectious diseases and antimicrobial resistance. This study aims to investigate the potential application of lytic bacteriophage, ozone nanobubbles (NB-O3), a potential combination of bacteriophage and nanobubble-based technology in combatting MDR A. hydrophila in Nile tilapia. A newly Myoviridae phage pAh6.2TG was isolated, identified, and characterized in this study. The application of this phage as a prophylactic agent significantly suppressed bacterial concentration in water and improved survivability of Nile tilapia challenged with the pathogenic MDR A. hydrophila with RPS of 50 73.3%. In addition, treatments of NB-O3 in a modified recirculation system were not only safe for juvenile Nile tilapia, but also modulated fish innate immunity and significantly improved survivability of Nile tilapia challenged with MDR A. hydrophila with RPS of 64.7 - 66.7%. The surviving fish from these treatments developed specific antibody IgM against the challenged bacteria. Taken together, this study reveals that phage pAh6.2TG and NB-O3 are promising non-antibiotic approaches to control diseases caused by MDR A. hydrophila in the freshwater fish aquaculture industry. Subsequently, an investigation of the impact of nanobubble technology on bacteriophage revealed that NB-O3 killed 99.99 and 100% bacteriophage in water after 5- and 10-min treatment, respectively, while oxygen nanobubbles (NB-O2) did not. The NB-O2 treatment improved the adherence of phage pAh6.2TG on fish body surface and the uptake of phages into the fish liver. Thus, a combination of NB-O2 treatment and phage therapy is feasible to control bacterial infections in aquaculture, while NB-O3 might be a promising viral disinfection method for aquaculture water. In summary, this study demonstrates that both bacteriophage and nanobubble technology are promising strategies for combatting MDR A. hydrophila in tilapia and probably other freshwater fish species.
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