Cirrhinus mrigala growth and health management: application of Lactobacillus acidophilus probiotic supplementation

Abstract

Labeo calbasu, Cyprinus carpio, Cirrhinus mrigala, Catla catla, and Labeo rohita are the major Indian carps and are widely consumed throughout India. Cirrhinus mrigala is vulnerable to bacterial infection in various ecological niches. They are easily infected by common bacterial pathogens, viz., Pseudomonas fluorescens and Aeromonas hydrophila. The survey revealed its occurrence in most of the waterbodies in Maharashtra, India. Pseudomonas fluorescens and Aeromonas hydrophila are known as opportunistic pathogens and have been associated with mass mortality incidences across the world. Opportunistic infections like Pseudomonas fluorescens and Aeromonas hydrophila are known to cause mass deaths all over the world. Antibiotics are frequently used by fish producers to combat these illness outbreaks. The rise of resistant pathogens and frequent treatment failures are nevertheless the results of preventive abuse. Probiotic lactic acid bacteria are being utilised more frequently in aquaculture to enhance the quality of seed production while reducing the need for antibiotics.

Twenty-seven isolates of lactic acid bacteria were isolated from different sources. The primary screening comprised the in-vitro inhibition of pathogenic Pseudomonas fluorescens and Aeromonas hydrophila isolates. Selected isolates of lactic acid bacteria with antagonistic properties were further subjected to biofilm formation. The strains were characterised morphologically and by biochemical tests. In-vivo experiments were undertaken with Pseudomonas fluorescens and Aeromonas hydrophila isolates on fingerlings of Cirrhinus mrigala. Lactobacillus acidophilus T22 was thus selected based on its attributes as a probiotic. The strain showed antagonistic activity, adhered strongly to polystyrene plates, and secured Cirrhinus mrigala with the best protection against Pseudomonas fluorescens and Aeromonas hydrophila isolates.

The lactic acid bacteria L. acidophillus T22 modified the profile of the bacterial community associated with fish larvae compared to the control group and reduced the bacterial load in fish larvae of Cirrhinus mrigala. The fish larvae's body bulk and length rose as a result of the probiotic treatment. The management of oxidative stress by L. acidophilus T22 appeared to be more effective due to two physiological markers for gene expression.