Effect of an Enzymatically Produced Galacto-oligosaccharides Mixture on the Growth of Probiotics

Galacto-oligosaccharides (GOS) are prebiotics that positively impact the gastrointestinal microbiome, boosting the growth of functional bacteria in the human gut. However, little is known of the quantitative effect of GOS on mixed bacterial growth. Our objective was to study whether a prebiotic mixture containing β-galactosidase derived from Lactobacillus helveticus OSU-PECh-4A had a prebiotic effect comparable to commercially used GOS products. We used three carbohydrate sources on modified de Man, Rogosa, and Sharpe (MRS) broth: lactose (LAC), a commercial GOS supplement (COM), and a GOS mixture from β-galactosidase isolated from Lb. helveticus OSU-PECh-4A (LHGOS), this last one was produced in our laboratory. We evaluated the optical density (OD600nm) and growth rate within the broths for Limosilactobacillus reuteri, Lactobacillus rhamnosus, Lactococcus lactis, and Bifidobacterium longum subsp. infantis for 22 h at 37 °C. The OD and maximum growth rate were higher for all strains in lactose as compared to oligosaccharides as sole carbon source. Lim. reuteri showed a preference towards COM having a difference in maximal growth rate >0.1 µmax h-1 and OD ~2 with LHGOS and 3 for COM. The difference in maximum growth rate and OD of the different strains is shown in the table included. Lcb. rhamnosus, B. longum, and L. lactis grew at a similar rate in the MRS broths with LHGOS and with COM. The LHGOS mixture showed a prebiotic effect comparable to the commercial product, with the advantage that, being produced by a lactic acid bacterium, this enzyme may be of lower cost, presenting a significant contribution to the future of prebiotic products derived from probiotic-derived enzymes.