Antibacterial Activity of Lactobacillus spp and Lactococcus spp Isolated from Various Parts of Pebbly Fish, Alestes baremoze

Abstract

The study sought to identify microbial communities and potential probiotics in one of the popular fish species, Alestes baremoze. A total of 15 samples were collected from Lake Albert and swabs of the skin, gills and gut were made, and cultured on general purpose and selective media. The bacteria isolated were confirmed using morphological and biochemical tests while probiotic screening was done using the agar spot method. The prevalent potential pathogenic bacteria were Staphylococcus aureus (100%) and Escherichia coli (67.7%). The highest total microbial load was generally recorded for samples from the skin. Staphylococcus spp had the highest total microbial load recorded from all the samples (skin, 8.50±22.1x102cfu/g and gills, 8.00±24.3x102 cfu/g). When the effect of potential probiotic genera (Lactobacillus spp and Lactococcus spp) isolated from skin, gills and gut was investigated, Lactobacillus spp showed the highest overall activity against all test pathogens. The highest activity for Lactobacillus spp was demonstrated against E. coli (15.4±0.19 mm) and S. aureus (14.0±0.17 mm). The highest activity for Lactococcus spp was demonstrated against S. aureus (8.7±0.12 mm) and E. coli (7.2±0.1 mm). Furthermore, no probiotic activity was recorded against Streptococcus spp and Pseudomonas spp. No significant (p> 0.05) differences in antimicrobial activity were noted using Lactic acid bacteria isolated from the different fish body parts. Based on the positive results from this study, Lactobacillus spp. should be further characterised and studied in challenge experiments in fish to explore its probiotic effects.