Isolation and Characterization of Putative Probiotics from Gut Microflora of “Lagao” (Nemipterus japonicus)

Abstract

This study aimed to identify and characterize the potential probiotic from the gut of Threadfin Bream (Nemipterus japonicus) or locally known as “Lagao” in Estancia, Iloilo, Philippines. Twenty-two (22) bacterial isolates were re-covered and characterized based on morphological (through Gram Staining) and biochemical characterization (O₂ Metabolites and Motility Tests), and enzymatic activity (amylase and cellulase). Isolates exhibited diverse characteristics, including varying oxygen requirements and significant amylase and cellulase activities, suggesting their potential role in enhancing digestion. Three (3) isolates, MCF1, HKF1, and DAF2, were selected based on their robust growth, and notable enzyme activities- potential for improving host health. These were identified as Oceanimonas smirnovii, Aeromonas veronii, and Bacillus licheniformis, respectively, using 16S rDNA sequencing. Only isolate DAF2, identified as B. licheniformis (a known probiotic), may hold significant potential for enhancing fish health, growth performance, and possible disease resistance in aquaculture through their probiotic properties.