Physiological Characteristics of Potential Probiotic Isolates of Lactobacillus rhamnosus (2016)
Undergraduates: Joshua Simpson, Jason W. Arnold, Jeff Roach, Andrea Montegudo-Mera, M. Andrea Azcarate-Peril
Faculty Advisor: Jason Arnold
Department: Chemistry
Probiotics are live microorganisms which, when administered in adequate amounts confer a health benefit to the host. The Lactic Acid Bacteria (LAB) is a group of beneficial bacteria that includes the genus Lactobacillus, which comprises numerous probiotic species. L. rhamnosus GG (LGG), a well known probiotic, provides significant benefits to the host, including immunomodulation, protection from pathogens, and promotion of the growth of other beneficial microbes within the gut. To function as a probiotic, microorganisms must be able to tolerate the environmental conditions of the host¿¿¿s gastrointestinal tract, including gastric low pH and high bile concentrations in the intestine. This study presents the characterization of novel strains of L. rhamnosus isolated from healthy human infants (AMC010, AMC143) and fermented milk (AMC004) as potential probiotics. We tested the impact of bile (Oxgall) and pH conditions ranging from 4.0 to 6.6 on growth rates of each isolate, as well as their ability to utilize prebiotics and other carbohydrate substrates. AMC143 had a significantly higher resistance to bile stress compared to AMC010 and AMC004, while exhibiting a decreased growth rate at pH 5. Additionally, each strain showed a unique carbohydrate metabolism profile. These differences suggest that despite the taxonomic similarity between these strains, physiological differences may impact their ability to function as effective probiotics.