Isolation and identification of potential host probiotic bacteria from Malaysian mahseer, Tor tambroides for aquaculture practices

Abstract

Abstract. Hossain MK, Iehata S , Noordin NM, Kader MA, Emilia SN, Sung YY, Abol-Munafi AB. 2022. Isolation and identification of potential host probiotic bacteria from Malaysian mahseer, Tor tambroides for aquaculture practices. Biodiversitas 23: 5423-5430. The digestive tract has been revealed as a reservoir of potential probiotics derived from the host. The goal of this study was to isolate, identify, and characterize putative host-associated probiotic bacteria (HAPs) from the digestive tract of Malaysian mahseer Tor tambroides. To evaluate potential T. tambroides HAPs, in-vitro digestive enzyme activity (such as a cellulolytic, proteolytic, and lipolytic activity) and antibacterial activity against two fish pathogens (Vibrio parahaemolyticus and Aeromonas hydrophila) were utilized. Thirty-seven isolates with digestive enzyme activities were tested for their ability to inhibit pathogenic bacteria growth using an agar well-diffusion assay. Three isolates displayed in-vitro suppression of pathogenic bacteria, with two strains (KT03 and KM07) inhibiting the growth of V. parahaemolyticus and one strain (KT27) suppressing the proliferation of both harmful bacteria (V. parahaemolyticus and A. hydrophila). Strains KT03 and KM07 exhibited the most resemblance to Enterococcus faecalis (strains 2674 and FC11682, respectively) based on 16S rRNA sequences, whereas KT27 had a 97% similarity to Aeromonas sp. A8-29. The study’s findings provide valuable data on the prospective use of these three isolates (KT03, KT27, and KM07) as potential HAPs for better understanding their physiological activities, such as growth and disease resistance on T. tambroides.