Endosymbiotic pathogen-inhibitory gut bacteria in three Indian Major Carps under polyculture system: A step toward making a probiotics consortium

The gastrointestinal (GI) microbiome in fish plays significant roles health and disease resistance. This investigation was accomplished to enumerate, characterize identify the potential probiotic bacteria from three Indian Major Carps (IMCs), viz., rohu (Labeo rohita), catla (Catla catla) mrigal (Cirrhinus mrigala) using culture dependent methods. Altogether, 105 pathogen-inhibitory (out of 1216 isolates) were detected IMCs by double layer assay. 16S rRNA partial gene sequence analyses BLAST search NCBI GenBank unveiled that 94.29% pathogen inhibitory bacilli (99 strains) Bacillus licheniformis far most common (28%). primarily selected 27 strains (cumulative inhibition score ?13) produced extracellular enzymes, while 15 them all six exo-enzymes studied (amylase, protease, lipase, cellulase, phytase xylanase). Gut stability became apparent their ability grow mucus tolerance diluted bile-juice. Finally, 14 noticed as ?-hemolytic susceptible commonly used antibiotics. Further, intra-peritoneal injection with did not induce any pathological signs or mortalities fish, thus considered safe. These isolates represented genus (13) Stenotrophomonas (1), which might form consortia for prospective use carp culture.