Antimicrobial activity of some plant extracts against Kosakonia sacchari causing diseases on a Vietnamese climbing perch (Anabas testudineus)

Abstract

The aquaculture of the climbing perch (Anabas testudineus) is presently focused on growth; however, pathogenic infections are an urgent threat, and multi-drug resistant bacteria may transfer and cause disease in other species. Due to its antimicrobial action and growth stimulant, herb medicine has been widely employed as feed additives in environmentally friendly strategies. This study was to investigate the in vitro and in vivo activity of EtOH 96% leaf extracts obtained from five plants including Anacardium occidentale (Ex1), Vitex negundo (Ex2), Vitex rotundifolia (Ex3), Acrostichum aureum L (Ex4), and Jasminum subtriplinerve Blume (Ex5). Using disk diffusion method, the Ex1 exhibited higher antibacterial effect than the other four plant extracts with a concentration of MIC at 12.5 µg/ml. Survival ratio was higher in fish challenged with selected virulence Kosakonia sacchari and then medicated by feed-supplemented with plant extract Ex1 compared to those in non-medicated group. In particular, EX1 help to protect fish from ammonia toxins with survival rates remain at 82%. In addition, supplementation with Ex1 also helped increase the weight gain of fish in each treatment respectively for each fish reach as 1.33 ± 0.07, 0.93 ± 0.03 and 1.35 ± 0.05 g. For efficacy protection of herb medicine. In conclusion, natural herb plant supplement to fish feed will have the potential to replace antibiotics in prophylaxis and be material for enhancing stress tolerant as well as growth promoter. Future study needs to conducted the protection efficacy in pilot scale of aquaculture.