Title : Probiotic Lactic Acid bacteria (LAB) associated with fermented millet-based milk beverage
Abstract:
Introduction: Our diet significantly influences our gut microbiome especially fermented foods which contain beneficial microorganisms known as probiotics. Brukina™, a fermented beverage originating from Burkina Faso, but widely consumed in Ghana is produced from cooked millet and fermented cow milk. For probiotics to be effective, they must survive the acidity levels and bile salt concentration in the gastrointestinal tract. Their adhesion to gastrointestinal epithelial cells is also crucial for colonization and persistence in the gut. Probiotic strains should have limited resistance to antibiotics. This study sought to characterize the Lactic Acid Bacteria (LAB) present in Brukina™ and their impact on the gut microbiome of consumers.
Methods: Food and Drugs Authority (FDA) approved Brukina™ samples were obtained from supermarkets in Accra, Ghana. LAB load was determined. 16S rRNA amplicons from cultured LAB strains and DNA extracts from Brukina™ was sequenced. Acid and bile tolerance, adhesion capacity, antimicrobial activity and antibiotic susceptibility profile of the isolated lactic acid bacteria were determined. Human participants and animal models were fed with Brukina™ samples for four weeks. Fecal samples were collected at different time points; DNA was extracted for 16S amplicon sequencing. Next generation sequencing was carried out and the sequence data was analyzed using metagenomics and Shannon indices.
Results: LAB load ranged from 10^4 CFU/ml to 10^6 CFU/ml. 16S rRNA sequencing of genomic DNA identified the cultured LAB strains as Lactobacillus fermentum, Lactobacillus delbrueckii, Lactobacillus johnsonii, Lactobacillus prophage, and Lactobacillus taiwanensis. Direct DNA extraction from Brukina™ showed the presence of Limosilactobacillus fermentum, Lactobacillus delbrueckii, Enterobacter hormaechei, Neobacillus fumarioli, Bacillus safensis and Faecalibaculum rodentia. The strains exhibited antimicrobial activity against four enteric pathogens (Escherichia coli NCTC 11954 TEM 1, K. pneumoniae NTC 13368, Salmonella typhi ACT 1, and Staphylococcus aureus). There was a notable increase in the abundance of LAB particularly, Lactobacillus delbrueckii and Lactobacillus fermentum in the gastrointestinal tracts of human participants and rat models after four weeks of consistent consumption of Brukina™. Most strains that adhered very well to IECs also exhibited a higher tolerance to acid and bile coupled with low resistance to orally administered antibiotics.
Discussion: Brukina™ is a promising probiotic or functional food due to its significant LAB content, ability to withstand low pH and bile conditions of the gut, strong adhesion capacity and antimicrobial activity. The LAB strains were also susceptible to antibiotics, hence a low risk of antimicrobial resistant. The abundance of lactic acid bacteria in the GIT tract after regular consumption of Brukina™, helps in the competitive elimination of enteric pathogens. The presence of a diverse range of microbes in the sample underscores the complexity of the microbial community in fermented millet-based milk beverage (Brukina™).
Conclusion: Brukina™ is a potential functional food with a significant LAB load. It also impacts the gut microbiome in a matter of three days of consistent consumption. The LAB strains have good probiotic potential and can be used as starter cultures.
