The effects of garlic-supplemented diets on antibacterial activity against Streptococcus iniae and on growth in orange-spotted grouper, Epinephelus coioides

Garlic (Allium sativum) has had an important dietary and medicinal role for centuries and has long been known to have broad antibacterial properties. Streptococcus iniae occurs naturally in marine and estuarine environments and is one of the major opportunistic pathogenic bacteria in wounded or unhealthy grouper. The purpose of this study was to investigate the in vitro antibacterial activity of garlic and the effect of garlic-supplemented diets on growth performance and resistance against S. iniae in orange-spotted grouper (Epinephelus coioides). The in vitro antibacterial activity of garlic against S. iniae was investigated with the agar well diffusion, minimum inhibitory concentration and minimum bactericidal concentration methods and showed a strong inhibitory effect. Fish were fed diets containing 0, 1.3 and 4% of garlic powder for 14days. The cumulative mortality of the fish fed with the 1.3% garlic diet was significantly (p