In vitro assessment of probiotic properties of Pseudomonas entomophila COFCAU_PEP4 isolated from Labeo rohita intestine

Assessment of beneficial properties by in vitro approaches forms the basis of selection of a potential probiotic. Moreover, bacterial strains of autochthonous origin are considered more useful than strains from allochthonous sources. In this study, a bacterial strain Pseudomonas entomophila COFCAU_PEP4, isolated from the intestine of Indian major carp rohu (Labeo rohita), was evaluated for its probiotic potential using a range of in vitro tests, along with safety assessment. The strain showed antagonistic activity against 12 pathogenic indicator bacteria and tolerance to a wide range of pH (2-9) and bile salt concentrations (up to 10%). The strain also demonstrated significant in vitro adhesion properties, including mucosal adherence, auto-aggregation capacity, and bacterial cell surface hydrophobicity. Besides being non-hemolytic, the strain COFCAU_PEP4 was able to produce extracellular enzymes and showed free radical scavenging potential. An experimental challenge study revealed the strain COFCAU_PEP4 as safe for L. rohita. Taken together, the in vitro and safety assessments demonstrated the probiotic potential of the strain P. entomophila COFCAU_PEP4 isolated from an autochthonous source.