Antibacterial Potentials of Lactobacillus plantarum from Fermented Food Origin as Probiotic Candidate in the Treatment of African Catfish (Clarias gariepinus) Bacterial Diseases

Abstract

Over the years, research on lactic acid bacteria isolated from fish gut against fish gram negative and fish gram positive pathogenic
bacteria have been carried out. In this study, lactic acid bacteria of fermented food origin (“wara and fufu”) were examined for
their probiotic potentials against fish bacterial pathogens. Samples from fermented cow milk (wara) and fermented cassava (fufu)
were stored in ice as: SW6, SW5, SW4, SF4, SF3, and SF2. Serial dilution was carried out with a 10-fold serial dilution. De
Man, Rogosa and Sharpe (MRS) agar and de Man, Rogosa and Sharpe (MRS) broth were prepared and used for bacterial growth.
Physiological, biochemical charactersations such as gram staining, bile salt tolerance, antibiotics susceptibility test and molecular
characterisation of Lactic acid bacteria were carried out. The results revealed that the isolates were gram-positive, catalase
negative, cocci, non-haemolytic, and non-pathogenic. The inhibition zones observed were: SW6 (24.7± 0.6) mm against
Aeromomas hydrophila, SF4 produced inhibition zone of (16.3±0.6) mm against Aeromomas hydrophila, inhibition zone of
(18.5±0.7) mm was produced in SF3 against Bacillus subtilis. All the isolates were susceptible to Chloramphenicol, Ampicillin,
Clindamycin and Erythromycin. Molecular characterisation of isolates with high inhibition zones using 16S ribosomal RNA
gene partial sequence identified two probiotic strains as SW6 and SF4. These strains were 99% identical to Lactobacillus
plantarum strains R762 and AT4. It was deduced from this study that, for the purpose of bio-conservation, probiotics isolated
from fermented food origin could replace fish-gut probiotics in treatment of fish bacterial diseases.