Isolation and characterisation of bifidobacteria populations in infants in the Khomas region, Namibia

Bacteria belonging to the genus bifidobacteria are reported to be the most abundant gut endosymbiotic flora in the intestinal tract of new-born infants, particularly those that have been exclusively breast-fed. This high concentration of this gram-positive anaerobic bacteria has been attributed to the prebiotic and bifidogenic factors present in human breast milk. Currently, there is limited information on the presence of bifidobacteri aspecies in Namibia. The aims of this study were to identify and characterize bifidobacteria, to profile their antimicrobial activity, test few of their probiotic characteristics such as bile, lysozyme, acid and H2O2 tolerance capabilities and to assess their diversity in infant faeces detected by genus specific PCR and presence of the caseinolytic protease C (ClpC) gene.A total of 25 faecal samples collected from Khomas region showed total plate counts ranging from 32.00 × 105 to 204 × 107colony forming units (CFU)/mL, with mean bifidobacteria plate count ranging from 1.4 × 104 CFU/mL to 3.6 × 108 CFU/mL. Bifidobacteria genus was confirmed by F6PPk assay further identified by 16S rDNA sequencing. Fourteen (14) of the 25bifidobacterial isolates demonstrated the ability to withstand the antimicrobial effects of extremes pH (pH 3.2 and 9.2), with 52 % isolates demonstrating the ability to grow at 0.7% bile concentration. Furthermore, fourteen isolates demonstrated ability to withstand the inhibitory effects of lysozyme and H2O2. These isolates demonstrated antagonistic activity against indicator strains. Using the well diffusion method, cell free supernatant (CFS) exhibited a high degree of antimicrobial activity against Listeria monocytogenes ATCC 13932, Candida albicans ATCC 13932, Escherichia coli ATCC 25922, Enterobacter aerogenes ATCC 13048, Salmonella typhi ATCC 13311, Staphylococcus aureus ATCC 25923, Clostridium perfringens .ATCC 13311, Enterococcus furans 6056, and Listeria innocuum ATCC 1450. Neutralized CFS with 1 M NaOH showed antimicrobial activity due to the action of bacteriocins or bacteriocin-like inhibitory substances (BLIS) against the same indicator strains. Antibiotic test revealed seven bifidobacterial isolates to be most susceptible to the effects of erythromycin, tetracycline and ampicillin. Six bifidobacteria isolates demonstrated good cell surface hydrophobicity and autoaggregation. Bifidobacteria present in stool samples are contemplated to have potential applications in food safety owing to the high antagonistic activities they have exhibited and may have probiotic applications in the dairy and food industries.

Grantor dc:publisher

University of Namibia

Year dc:date.issued

2020

Author dc:creator

• Nambundunga, Aina M.

• Bifidobacteria
• Infants

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/11070/2866

OAI identifier oai:identifier

oai:repository.unam.edu.na:11070/2866