Evaluation of the probiotic and postbiotic potential of lactic acid bacteria from artisanal dairy products against pathogens

Abstract

Introduction: Probiotic and postbiotic potential of thirty-two strains of lactic acid bacteria (LAB), obtained earlier from artisanal dairy sources in Pakistan, have been investigated against major multi-drug resistant (MDR) and food borne pathogenic bacteria.
 Methodology: LAB strains were identified by 16S rRNA gene sequencing and their antibacterial activity was assessed by the microdilution method. Four LAB isolates, Weissella confusa PL6, Enterococcus faecium PL7, and Lactobacillus delbrueckii PL11 and PL13 were shortlisted. Their ability to degrade lactose and safety for human consumption in terms of hemolysis and antibiotic susceptibility were assessed in vitro. The antibacterial components in the cell-free supernatants (CFSs) of isolate cultures were characterized biochemically by HPLC.
 Results: Acid neutralization but not protease treatment abolished the antibacterial activity of CFSs. Lactic, acetic and propionic acids were the main acids in the CFSs, and acid production peaked in the stationary phase of growth. The antibacterial activity of the LAB cultures resulted from secretion of organic acids that lowered the pH. The strains exhibited variable ability to degrade lactose and were non-hemolytic and susceptible to the most common antibiotics.
 Conclusions: These LAB strains are probiotic candidates for further investigation of their postbiotic role in naturally preserving processed foods and for attenuation of lactose intolerance.

Potential Probiotic Enterococcus faecium OV3-6 and Its Bioactive Peptide as Alternative Bio-Preservation

“…CFS's antimicrobial activities produced by E. faecium OV3-6 were active in a narrow spectrum against Gram-positive bacteria but not against Gram-negative bacteria and yeast (Table 2). The various antimicrobial substances secreted in CFS of LAB include organic acids (such as lactic acid, acetic acid, and propionic acid) [68,69], hydrogen peroxide, bacteriocins [59], and other compounds such as some RPs [15,70]. Most of the bacteriocin show inhibit the growth of closely related species [71].…”

Isolation and identification of Lacticaseibacillus rhamnosus YT and the antibacterial characteristics of its cell free supernatant and cells

“…bacteriocin and peptides [14]. Acid neutralization but not protease treatment abolished the antibacterial activity of the CFSs of four LAB isolates (Weissella confusa PL6, Enterococcus faecium PL7, L. delbrueckii PL11 and PL13), suggesting that the antibacterial activity of the LAB cultures resulted from secretion of organic acids [15]. Plantaricin ZJ008 produced by L. plantarum ZJ008 exhibited narrow pH stability (pH 4.0-5.0) and plantaricin JY22 from L. plantarum JY22 activated at pH ranging from 2.5 to 5.5 [16,17].…”

Characterization of Genomic, Physiological, and Probiotic Features of Lactiplantibacillus plantarum JS21 Strain Isolated from Traditional Fermented Jiangshui

“…During growth, the JS21 strain reduced the pH of the medium to 3.74 (Figure S6). Probiotic bacteria typically resist pathogenic microorganisms by producing organic acids [103]. Extracellular polysaccharides (EPS) effectively inhibit the biofilm formation of pathogenic bacteria, thereby affecting their viability [104].…”