Dietary Onion or Ginger Modulates the Stress Response and Susceptibility to Vibrio harveyi JML1 Infection in Brown‐marbled Grouper Epinephelus fuscoguttatus Juveniles

Abstract

Onion Allium cepa and ginger Zingiber officinale have health-promoting properties that qualify them as functional foods. The effect of repeated acute stressors was examined in juvenile Brown-marbled Grouper Epinephelus fuscoguttatus that were fed four diets supplemented with onion at 1.8%, ginger at 1.8%, vitamin C at 0.86%, and β-glucan at 0.8% of the diet. The non-supplemented diet served as the control. After 12 weeks of feeding, fish were exposed to stressors and were experimentally infected with a fish pathogen, the bacterium Vibrio harveyi JML1. After repeated exposure to hypoxia, cortisol levels rose significantly in the non-supplemented fish compared to those fed onion, ginger, β-glucan, or vitamin C. Within groups, postexposure cortisol levels in the onion-, ginger-, and vitamin C-fed fish did not change relative to pre-stress levels, whereas significant increases in poststress values were observed in the control and β-glucan groups. The net cortisol increase was also significantly greater in the non-supplemented group compared to the supplemented groups. The net cortisol increase did not vary among the supplemented groups except that the β-glucan-fed group exhibited a higher net increase than the onion-fed group. Similarly, repeated acute exposure to osmotic stress significantly increased the plasma cortisol level in the non-supplemented group compared to groups that received supplements; no differences were found in the supplemented groups except the β-glucan group. Within groups, significant increases in poststress values relative to pre-stress levels were found only in the control and β-glucan groups. Repeated acute exposure to hypoxia significantly increased cumulative mortality in the control group compared to the supplemented groups (except the β-glucan group), whereas repeated exposure to acute osmotic stress significantly increased cumulative mortality only in the control group 10 d after infection with V. harveyi JML1. Based on our collective results, most of the supplemented groups performed better than the control, but the best supplements were onion and ginger in terms of enhancing stress tolerance and increasing survival of Brown-marbled Grouper upon infection with V. harveyi JML1.

Quorum sensing is required for full virulence of Vibrio campbellii towards tiger grouper (Epinephelus fuscoguttatus) larvae

“…Further, the fish were infected by intraperitoneal injection in the study by Amar et al. (), whereas they were cultured in sea water containing V. campbellii in our study. Finally, strain JML1 might be more virulent than strain BB120.…”

“…These results are consistent with previous reports documenting the pathogenicity of Vibrio strains to various fish species, including kelp grouper ( E. bruneus ) (Harikrishnan, Balasundaram, & Heo, ), orange‐spotted grouper ( E. coioides ) (Nguyen et al., ) and hybrid grouper (E. fuscoguttatus x E. lanceolatus) (Shen et al., ). Very recently, pathogenicity of V. harveyi (strain JML1) was also documented in tiger grouper ( E. fuscoguttatus ) (Amar et al., ). The latter study reported higher mortality rates (80% or more after 4 days) than obtained in our study, which might be due to a number of factors.…”

“…First, Amar et al. () exposed the animals to stress (hypoxia or osmotic stress) before challenged with V. harveyi , which will probably have increased the susceptibility of the fish (Snieszko, ). Further, the fish were infected by intraperitoneal injection in the study by Amar et al.…”

“…First, Amar et al (2018) exposed the animals to stress (hypoxia or osmotic stress) before challenged with V. harveyi, which will probably have increased the susceptibility of the fish (Snieszko, 1974). Further, the fish were infected by intraperitoneal injection in the study by Amar et al (2018), whereas they were cultured in sea water containing V. campbellii in our study. Finally, strain JML1 might be more virulent than strain BB120.…”

Zingiber officinale and Glycyrrhiza glabra , individually or in combination, reduce heavy metal accumulation and improve growth performance and immune status in Nile tilapia, Oreochromis niloticus

“…Ginger ( Zingiber officinale ) and liquorice ( Glycyrrhiza glabra ) are two herbal extracts with promising properties as functional feed for aquaculture (Shakya, ; Smith, Christian, Taylor, Santander, & Rise, ; Tiwari et al, ). For example, ginger has been shown to improve immunity and enhance growth in several fish species such as tilapia ( Oreochromis mossambicus , Immanuel et al, ), European sturgeon ( Huso huso , Kanani, Nobahar, Kakoolaki, & Jafarian, ), carps ( Labeo rohita , Sukumaran, Park, & Giri, ), Rainbow trout ( Oncorhynchus mykiss , Nya & Austin, ; Shaluei, Nematollahi, Naderi‐Farsani, Rahimi, & Katadj, ), Asian sea bass ( Lates calcarifer , Talpur, Ikhwanuddin, & Ambok Bolong, ) and grouper ( Epinephelus fuscoguttatus , Amar, Apines‐Amar, & Faisan, ). Dietary supplementation of ginger extract maintained the morphology and function of the tissues and ameliorated the tissue damage following infection in Nile tilapia (Brum et al, ).…”