Probiotic Potential and Modulatory Effects of Mixed Culture of Lactic Acid Bacteria on Mice Infected With <i>Escherichia coli</i> O157:H7

Probiotics, particularly lactic acid bacteria (LAB), are increasingly recognized for their role in modulating gut microbiota and promoting health. This study investigates the probiotic potential of LAB isolated from Kunun zaki , a Nigerian fermented cereal beverage, in mitigating Escherichia coli O157:H7‐induced diarrhea in mice. Five LAB isolates were screened for probiotic traits, with Lactococcus lactis and Lactobacillus brevis identified via the Analytical Profile Index 50CHL kit as the most promising candidates. In vivo experiments involved 15 male Wistar mice divided into five groups ( n = 3 per group): three treatment groups (T1: L. lactis , T2: L. brevis , T3: mixed L. lactis and L. brevis ), a positive control (infected, untreated), and a negative control (uninfected). Mice infected with E. coli O157:H7 exhibited increased rectal temperature (from 35.8 ± 1.80 ° C to 44 ± 0.50 ° C), frequent loose stools, and reduced body weight. Posttreatment with LAB (0.5 mL/10 8 CFU/mL for 5 days), all treatment groups showed recovery, with normalized temperature (36.2 ± 1.52 ° C), stool texture, and weight gain. Bacteriological analysis revealed a significant increase in LAB counts, particularly in T1 ( L. lactis ), from 320.33 ± 6.06 to 871.67 ± 5.48 CFU/g ( p &lt; 0.05). Hematological and liver function tests showed no significant differences between treated and control groups, except for elevated hematocrit in T3 and reduced total bilirubin in treated groups ( p &lt; 0.05). These findings highlight the strong probiotic and therapeutic potential of L. lactis from Kunun zaki against E. coli O157:H7, supporting further research into its application in commercial probiotic production to enhance gut health and combat diarrheal diseases.