Elucidating the Probiotic Potential of Malaysian Paenibacillus pabuli Against Vibrio alginolyticus in Artemia Culture

In the present study, two strains of Malaysian Paenibacillus spp. isolated from intestinal tract of cultured hybrid red tilapia were tested for their antagonistic activity against Vibrio alginolyticus, a destructive bacterial pathogen to marine fishes as probiotics in aquaculture. Homology searches of 16S rRNA and Internal Transcribes Spacer (ITS) genes sequencing with nucleotide Basic Local Alignment Sequence Tool (nBLAST) revealed that both strains were identical to Paenibacillus spp. and Paenibacillus pabuli, respectively. In vitro and in vivo experiments were conducted to study the efficacy of these Paenibacillus strains as probiotics. Co-culture assay demonstrated that the growth of V. alginolyticus was inhibited when grown with these probionts. A complete inhibition of the pathogen by P. pabuli strain D12 occurred at 48 h of incubation period. To qualify strains as probiotics, Artemia challenged with V. alginolyticus was performed, with or without these potential probiotics. The highest survival rate (72%) of Artemia was observed in P. pabuli strain D12 treatment after challenged with V. alginolyticus, followed by P. pabuli strain D14 at 68% survival rate. The lowest survival of Artemia (23% survival rate) was recorded when challenged with only V. alginolyticus. This study reported the ability of Paenibacillus D12 and D14 as potential probiotics to control V. alginolyticus in Artemia culture system.