Evaluation of the Potential Use of Oxy-Hydrogen Gas for the Treatment of Lactococcus garvieae Infected- Zebrafish in Hydrogen-Rich Water Aquarium

Abstract

This study aimed to evaluate the use of an oxy-hydrogen generator for preparing hydrogen-rich water (HRW) and studying its effects on the L. garvieae-affected zebrafish. 0, 10, 20, and 100% HRW were prepared to determine the effects of HRW on the mortality rate and gene expression levels of L. garvieae infected-zebrafish. After 48 hours of bacterial injection, the mortality rate of fish was 0, 0, 0, 66, 80, and 100% for the non-infected and non-HRW (G1), infected and 100% HRW (G5), non-infected and 100% HRW (G6), infected and 20% HRW (G4), infected and 10% HRW (G3), and infected without HRW (G2) groups. After 54 hours, there was a non-significant change in immunity-related gene expression levels (IL-1β and IL-6) between non-infected 100% HRW (G6) and non-infected non-HRW control (G1) groups. Gene expression levels were significantly upregulated for IL-1β (14, 13, and 9 times), 48, and 22 times), and SOD (9 times for each) genes in G2, G3, and G4 groups, respectively, but not for G5 comparing with control group G1. IL-1β and IL-6 gene expression levels decreased with the increase of hydrogen levels in the water. These results show that HRW could decrease (G3 and G4) and prevent (G5) the mortality of L. garvieae infectedzebrafish. This demonstrates the importance of the application of HRW for the treatment of bacterial infectious diseases of fish using a non-toxic compound as a green method without any residual effects on fish or water. HIGHLIGHTS• Hydrogen-rich water can be applied as non-toxic compound for the treatment of bacterial infectious diseases of fish without any residual effects on fish or water.• IL-1 and IL-6 gene expression levels decreased with the increase of hydrogen levels in the water• HRW could reduce and prevent the death of zebrafish infected with L. garvieae (G5).

The Effects of Different Concentrations of Hydrogen-Rich Water on the Growth Performance, Digestive Ability, Antioxidant Capacity, Glucose Metabolism Pathway, mTOR Signaling Pathway, and Gut Microbiota of Largemouth Bass (Micropterus salmoides)

“…This study showed that no significant changes in the muscle layer thickness, mucosal thickness, villus width, and villus height occurred in largemouth bass treated with HRW. This is consistent with previous research [23]. This result indicates that HRW maintains the integrity and stability of the intestinal structure.…”

“…On the contrary, long−−term (180 days) HRW (1200 ppb) intervention can reduce the weight of rats [22]. Therefore, there was a dose-−response effect of hydrogen on animal growth [23]. In order to explore the appropriate concentration of hydrogen in largemouth bass, we set up two treatments.…”

“…It is worth noting that some studies have reported the regulatory effect of H2 on the gut microbiota [45][46][47]. However, there were only a few reports on the effects of H2 on gut bacteria in fish [23]. Some studies have shown that HRW or H2 can alter the structure of gut microbiota, increasing its abundance and diversity [46,48].…”