Antimicrobial Activity of Lactic Acid Bacteria Starters against Acid Tolerant, Antibiotic Resistant, and Potentially VirulentE. coliIsolated from a Fermented Sorghum-Millet Beverage

Abstract

Bacterial contamination of fermented foods is a serious global food safety challenge that requires effective control strategies. This study characterized presumptive E. coli isolated from Obushera, a traditional fermented cereal beverage from Uganda. Thereafter, the antimicrobial effect of lactic acid bacteria (LAB) previously isolated from Obushera, against the E. coli, was examined. The presumptive E. coli was incubated in brain heart infusion broth (pH = 3.6) at 25°C for 48 h. The most acid-stable strains were clustered using (GTG)5 rep-PCR fingerprinting and identified using 16S rRNA sequencing. E. coli was screened for Shiga toxins (Stx 1 and Stx 2) and Intimin (eae) virulence genes as well as antibiotic resistance. The spot-on-the-lawn method was used to evaluate antimicrobial activity. Eighteen isolates were acid stable and are identified as E. coli, Shigella, and Lysinibacillus. The Stx 2 gene and antibiotic resistance were detected in some E. coli isolates. The LAB were antagonistic against the E. coli. Lactic acid bacteria from traditional fermented foods can be applied in food processing to inhibit pathogens. Obushera lactic acid bacteria could be used to improve the safety of fermented foods.

Evaluation of potential lactic acid bacteria single starter cultures for production of traditional Ivoirian cereal beverages

“…The lactic acid content of sweet wort was highest to those of sour wort. This highest content would develop the desired flavor and reduce pH thus preventing growth of undesirable microorganisms and contributing to the development of the desired sensory qualities [26]. In the tchapalo, there was not acetic acid detected.…”

“…The beverages such as sweet wort and tchapalo produced with single starter cultures had the ability to inhibit E. coli, S. typhi and S. aureus. Their inhibitory effects could be related to their organic acids content and composition [1,8,26]. Indeed, Byakika et al [26] reported that organic acids inhibit pathogens by entering into cells in an undissociated form and dissociating within the cytoplasm.…”

“…Their inhibitory effects could be related to their organic acids content and composition [1,8,26]. Indeed, Byakika et al [26] reported that organic acids inhibit pathogens by entering into cells in an undissociated form and dissociating within the cytoplasm. This lowers the intracellular pH, and to maintain balance, cells use ATP to expel the excess hydrogen ions.…”

The Complex Role of Lactic Acid Bacteria in Food Detoxification

“…casei Shirota was due to local immune response enhancement and STEC cell elimination, which consequently reduced toxin levels in the gut. Byakika et al [ 71 ] revealed the antimicrobial effect of Lp. plantarum , Lactococcus lactis , W. confusa , and Lc.…”

A Novel Strain of Probiotic Leuconostoc citreum Inhibits Infection-Causing Bacterial Pathogens

“…Lactic acid bacteria (LAB) produce a variety of secondary metabolites that are potential antimicrobials, antioxidants and other biological agents [ 8 , 9 , 10 ]. The secondary metabolites of LAB inhibit pathogen growth via multiple molecular mechanisms [ 11 , 12 , 13 , 14 , 15 ]. LAB can also prevent the attachment of pathogenic microbes to the epithelial cells by competing with pathogens and reducing colonization of pathogens, thereby reducing infection [ 16 , 17 , 18 ].…”