Genotypic characterization and safety assessment of lactic acid bacteria from indigenous African fermented food products

Abstract

BackgroundIndigenous fermented food products play an essential role in the diet of millions of Africans. Lactic acid bacteria (LAB) are among the predominant microbial species in African indigenous fermented food products and are used for different applications in the food and biotechnology industries. Numerous studies have described antimicrobial susceptibility profiles of LAB from different parts of the world. However, there is limited information on antimicrobial resistance profiles of LAB from Africa. The aim of this study was to characterize 33 LAB previously isolated from three different African indigenous fermented food products using (GTG)5-based rep-PCR, sequencing of the 16S rRNA gene and species-specific PCR techniques for differentiation of closely related species and further evaluate their antibiotic resistance profiles by the broth microdilution method and their haemolytic activity on sheep blood agar plates as indicators of safety traits among these bacteria.ResultsUsing molecular biology based methods and selected phenotypic tests such as catalase reaction, CO2 production from glucose, colonies and cells morphology, the isolates were identified as Lactobacillus delbrueckii, Lactobacillus fermentum, Lactobacillus ghanensis, Lactobacillus plantarum, Lactobacillus salivarius, Leuconostoc pseudomesenteroides, Pediococcus acidilactici, Pediococcus pentosaceus and Weissella confusa. The bacteria were susceptible to ampicillin, chloramphenicol, clindamycin and erythromycin but resistant to vancomycin, kanamycin and streptomycin. Variable sensitivity profiles to tetracycline and gentamicin was observed among the isolates with Lb. plantarum, Lb. salivarius, W. confusa (except strain SK9-5) and Lb. fermentum strains being susceptible to tetracycline whereas Pediococcus strains and Lb. ghanensis strains were resistant. For gentamicin, Leuc. pseudomesenteroides, Lb. ghanensis and Ped. acidilactici strains were resistant to 64 mg/L whereas some W. confusa and Lb. plantarum strains had a MIC value of 16 mg/L and 32 mg/L respectively. No β-haemolytic activity was observed, however, α-haemolytic activity was observed in 27% (9) of the strains comprising Lb. salivarius (6), W. confusa (2) and Lb. delbrueckii (1) isolates.ConclusionsThe resistance to kanamycin and vancomycin is probably an intrinsic feature since similar observations were reported in the literature for LAB. Low prevalence of pathogenicity indicator traits were observed among the isolates especially with the presence of poor haemolytic activities and they could therefore be considered as interesting candidates for selection of starter cultures or probiotics for different applications.

Screening, Characterization and In Vitro Evaluation of Probiotic Properties Among Lactic Acid Bacteria Through Comparative Analysis

“…Similarly, Devi and Halami [17] have characterized different bacteriocin-producing LAB by RFLP and RAPD typing tools. (GTG) 5 PCR was reported to have the discriminatory power and reproducibility at species and sub-species level among LAB [32]. Based on the results obtained, (GTG) 5 can be considered as a better method for characterization of probiotic cultures at their strain level.…”

“…The auto-aggregation and cell surface hydrophobicity properties were studied to assess the adherence ability of probiotic bacteria to intestinal epithelial mucosal cells and are found to be strongly co-related among several Lactobacillus and Bifidobacteria cultures [32]. Bacterial cells with high hydrophobicity were found to have either strong interaction towards mucosal cells or have a strong affinity of adherence to epithelial and/or mucous layers [34,35].…”

Antibiotic resistance, hemolysis and biogenic amine production assessments of Leuconostoc and Weissella isolates for kimchi starter development

“…However, hemolytic activities of LAB have been reported in other studies selecting starter cultures and probiotics (Adimpong, Nielsen, Sorensen, Derkx, & Jespersen, 2012;Ruiz-Moyano et al, 2009), and poor a-hemolytic activity was not considered a high risk for human health (Adimpong et al, 2012). The Leuconostoc and Weissella isolates from kimchi do not therefore present a higher risk in terms of antibiotic resistance profiles and hemolytic activities compared with LAB isolates from other geographical areas.…”

Assessment of Antibiotic Susceptibility within Lactic Acid Bacteria and Coagulase‐Negative Staphylococci Isolated from Hunan Smoked Pork, a Naturally Fermented Meat Product in China

“…JFDS-2017-0765 Submitted 6/6/2017, Accepted 3/8/2018 LAB are a group of Gram-positive, catalase-negative bacteria that share the capacity of fermenting sugar into lactic acid (Toomey, Monaghan, Fanning, & Bolton, 2009). They have been classified as "generally recognized as safe" (GRAS) due to their widespread occurrence in fermented foods and in the human commensal microflora (Adimpong, Nielsen, Sørensen, Derkx, & Jespersen, 2012). During the fermentation of meat products, LAB dominate the environment rapidly and reduce the pH of meat by producing lactic acid.…”