Bio-therapeutic potential of lactic acid bacterial against <i>Aeromonas</i> species

Abstract

Among the microorganisms responsible for human deaths from gastroenteritis, little or no attention is given to Aeromonas species. Due to wrong diagnosis and virulence properties exhibited by Aeromonads including drug resistant profile, these organisms have constituted challenges in public health, which may however, needed alternative control strategy. Lactic acid bacteria (LAB) are generally regarded as safe and confer health benefit in humans due to antimicrobial compounds produced and could be used to control infections caused by Aeromonas species. Aeromonas species and LAB were characterized using 16S rRNA. Bacteriocin production and antagonistic activity of LAB metabolites against Aeromonas species were determined using agar well diffusion and the best LAB selected based on the above parameters for in vivo tests. The effect of the selected LAB on Wistar rat infected with selected Aeromonas species based on virulence properties produced was determined through haematological, serum enzymes (alanine amino tranferase (ALT), alkaline phosphatase (ALP) and aspartate amino transferases (AST) and histopathology analysis. Data were analysed using descriptive statistics and ANOVA at α_0.05. The 16S rRNA confirmed Aeromonas species as A. hydrophilla A. caviae, A. veronii, A. simiae, A. punctata, A. finlandiensis, Plesiomonas shigelloides and LAB as Lactobacillus plantarum (LAB 01), Lactobacillus paraplantarum (LAB02), Lactobacillus fermentum (LAB3) and Lactobacillus oris(LAB 04). Antagonistic activity of both the LAB metabolites and bacteriocin showed inhibition zones ranging from 18-31mm against Aeromonas species. Lactobacillus plantarum (LAB01) produced 90.15 mg/100g of lactic acid. Wistar rats infected with A. hydrophila (ST08) and administered with L. plantarum (LAB01) showed no significant differences from the control rats in terms of haematology, enzymatic and histopathology parameters. However, Wister rats infected with A. hydrophila (ST07) only had 17.47±0.01x10⁹/L white blood cells compared to the control (2.31 ± 0.14x10⁹/L). Enzymatic values revealed high ALT (34.13 ± 0.01IU/L), AST (37.11 ± 0.00IU/L) and ALP (32.13 ± 0.02IU/L) against control (16.03 ± 0.03 - 24.10 ± 0.01IU/L). Histopathology analysis revealed renal cortex showing global necrosis in infected rats. Howe Lactobacillus plantrum (LAB01) produced antimicrobial compounds that inhibited multiple antibiotic resistant Aeromonas species in vitro and in vivo and could be used as bio-therapeutic agents against Aeromonads infection.

Keywords: Aeromonas species, lactic acid bacteria, Wister rats, bacteriocin, organic acid