Prebiotic Galactooligosaccharide Metabolism by Probiotic Lactobacilli and Bifidobacteria

Area of Science:

• Microbiology
• Nutritional Science
• Gastroenterology

Background:

• Galactooligosaccharides (GOS) are recognized as prebiotics that promote beneficial gut bacteria.
• However, the ability of different bacterial strains to utilize GOS varies significantly.
• Strain-specific GOS metabolism impacts their efficacy as prebiotics.

Purpose of the Study:

• To investigate the in vitro growth and GOS utilization capabilities of commercially available probiotic strains.
• To characterize the GOS utilization profiles of specific bifidobacteria and lactobacilli.
• To elucidate the enzymatic basis for GOS metabolism in Lactobacillus acidophilus NCFM.

Main Methods:

• Culturing of selected probiotic bifidobacteria and lactobacilli strains in the presence of GOS.
• Analysis of GOS utilization patterns based on degree of polymerization (DP).
• Assay of extracellular β-galactosidase activity and galactose accumulation.
• Genetic analysis of a LacL-deficient Lactobacillus acidophilus NCFM strain.

Main Results:

• Multiple bifidobacteria and lactobacilli strains demonstrated growth on GOS, but with distinct utilization profiles.
• Three distinct GOS utilization patterns were observed, categorized by DP.
• Lactobacillus acidophilus NCFM efficiently consumed all GOS oligomers.
• Extracellular β-galactosidase activity in Lactobacillus acidophilus NCFM correlated with galactose production, and a LacL-deficient mutant showed no GOS utilization.

Conclusions:

• GOS utilization by probiotic strains is strain-specific and dependent on the degree of polymerization.
• Lactobacillus acidophilus NCFM exhibits broad GOS utilization, facilitated by its LacL enzyme.
• Consideration of in vitro GOS utilization is crucial when co-administering GOS with probiotics.