Michaela Brubaker

Animal, Dairy, and Veterinary Sciences

Mentor: Dr. Abby Benninghoff

Fermentation of Prebiotics in Whole Food Powders by Probiotic Lactic-acid Producing Bacterial Strains to Identify Synbiotic Combinations

The Western diet is a major risk factor for development of colorectal cancer and is linked to dysbiosis of the gut microbiome. Dietary interventions with probiotic lactic acid bacteria (LAB) and prebiotics, complex dietary fibers that promote LAB growth, may favorably shift the gut microbiome to reduce colorectal cancer risk. Our primary hypothesis was that the LAB strains NCFM Lactobacillus acidophilus and NH10 Bifidobacterium lactis will thrive in the presence of agave, green banana, black raspberry, pomegranate peel, or baobab fruit whole food powders by fermenting oligosaccharide (OS) components into lactic acid end products. LAB strains were cultured in media with no carbohydrate, purified OS, or either one of the whole food powders. LAB strains cultured with agave powder appeared to grow better than purified OS as determined by the optical density measurement of the culture medium (p<0.05). Also, the medium pH for LAB strains cultured with agave or black raspberry powder decreased significantly more than with purified OS (p<0.0001), indicating a greater rate of fermentation. However, the effect of black raspberry on bacteria growth could not be determined because the powder made the culture medium too opaque for measurements. The medium pH of B. lactis cultured in baobab fruit powder decreased significantly more than with purified OS (p<0.0001), whereas no difference was observed in culture medium of L. acidophilus. Optical density measurements suggested that baobab fruit powder did not support growth of L. acidophilus, though B. lactis grew in the presence of baobab as well as the purified OS. Lastly, green banana or pomegranate peel powder appeared not to support growth of either LAB strain nor was culture media pH changed, indicating no effect on bacterial fermentation. Overall, these data suggest that agave, black raspberry, or baobab fruit powder, but not green banana nor pomegranate peel powder, may have a greater fermentation capacity than purified OS. However, due to the low transparency of some culture mediums, changes to optical density quantification need to be made to better measure the effects on LAB growth.