Lactococcus lactis MA5 is a potential autochthonous probiotic for nutrient digestibility enhancement and bacterial pathogen inhibition in hybrid catfish (Ictalurus punctatus × I. furcatus)

Authors: HUANG, JING - Mississippi State University; JORDAN, HEATHER - Mississippi State University; Older, Caitlin; GRIFFIN, MATT - Mississippi State University; ALLEN, PETER - Mississippi State University; WISE, DAVID - Mississippi State University; GOODMAN, PENELOPE - Mississippi State University; REIFERS, JONATHAN - Mississippi State University; YAMAMOTO, FERNANDO - Mississippi State University

Submitted to: Journal of Fish Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/24/2024
Publication Date: 7/7/2024
Citation: Huang, J., Jordan, H., Older, C.E., Griffin, M.J., Allen, P.J., Wise, D.J., Goodman, P.M., Reifers, J.G., Yamamoto, F.Y. 2024. Lactococcus lactis MA5 is a potential autochthonous probiotic for nutrient digestibility enhancement and bacterial pathogen inhibition in hybrid catfish (Ictalurus punctatus × I. furcatus). Journal of Fish Diseases. 47(10)e13997. https://doi.org/10.1111/jfd.13997.
DOI: https://doi.org/10.1111/jfd.13997

Interpretive Summary: Catfish producers in the United States desire methods to prevent disease and improve feed efficiency to promote sustainable production. Scientists at Mississippi State University and the USDA, ARS, Warmwater Aquaculture Research Unit in Stoneville, MS, collaborated to compare the bacterial communities present in the digesta of overperforming and underperforming hybrid catfish to identify candidate probiotic microorganisms. Through a series of screening processes, a Lactococcus lactis isolate (MA5) could inhibit growth of important catfish pathogens in vitro. Genome sequencing of this isolate revealed genes related to amino acid and vitamin synthesis, suggesting potential nutritional benefits to the host. The team identified a preservation method which permitted 83% probiotic survival even after storage at -20°C for 14 days. The hybrid catfish-derived Lactococcis lactis isolate MA5 shows promise as a valuable probiotic that can improve catfish production efficiency.

Technical Abstract: With the emergence of diseases, the U.S. catfish industry is under challenge. Current trends prefer autochthonous bacteria as potential probiotic candidates owing to their adaptability and capacity to effectively colonize the host's intestine, which can enhance production performance and bolster disease resistance. The objective of this study was to isolate an autochthonous bacterium as probiotic for hybrid catfish. Initially, an analysis of the intestinal microbiota of hybrid catfish reared in earthen ponds was conducted for subsequent probiotic development. Twenty lactic acid bacteria were isolated from the digesta of overperforming catfish, and most of the candidates demonstrated probiotic traits, including proteolytic and lipolytic abilities; antagonistic inhibition of catfish enteric bacterial pathogens, negative haemolytic activity and antibiotic susceptibility. Subsequent to this screening process, an isolate of Lactococcus lactis (MA5) was deemed the most promising probiotic candidate. In silico analyses were conducted, and several potential probiotic functions were predicted, including essential amino acids and vitamin synthesis. Moreover, genes for three bacteriocins, lactococcin A, enterolysin A and sactipeptide BmbF, were identified. Lastly, various protectant media for lyophilization of MA5 were assessed. These findings suggest that Lactococcus lactis MA5 can be an autochthonous probiotic from hybrid catfish, holding promise to be further tested in feeding trials.