Piper betle Leaf Extract Inhibits Multiple Aquatic Bacterial Pathogens and In Vivo Streptococcus agalactiae Infection in Nile Tilapia

Özet

An in vitro assessment of antimicrobial properties of aqueous and ethanol extracts from solo garlic (Allium sativum),garlic chive (Allium tuberosum) and betel leaves (Piper betle) on six bacterial pathogens in aquaculture, and a challenge ofNile tilapia, Oreochromis niloticus with Streptococcus agalactiae were performed. Generally, minimum inhibitoryconcentrations (MIC) ranged from 26.63 to 53.25 mg $mL^{-1}$for aqueous solo garlic (G) and 14.60 to 29.20 mg $mL^{-1}$for garlicchive extracts for all pathogens tested. Ethanol extract of betel leaves (P) exhibited the strongest antibacterial activity (0.15 –0.60 mg $mL^{-1}$). P and G incorporated in feed at high and low doses as multiples of MIC [High; H (10X for PH and 3X forGH) and Low; L (3X for PL and 1X for GL)] were fed to tilapia followed by in vivo challenge against S. agalactiae (1 x $10^8$CFU $mL^{-1}$). Ethanol extract of P. betle significantly improved survival (P<0.05; PH=100%, PL =77%). White blood cells(WBC), lymphocytes and monocytes differed significantly (P<0.05) among treatments and the highest WBC value (1.175 ×$10^3$) was for PH. Use of ethanol extract of Piper betle seems promising for sustainable disease management in aquaculture.