Identification of Lactobacillus strains capable of fermenting fructo-oligosaccharides and inulin

Authors: Renye, John; White, Andre; Hotchkiss, Arland

Submitted to: Beneficial Microbes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/19/2021
Publication Date: 9/24/2021
Citation: Renye Jr, J.A., White, A.K., Hotchkiss, A.T. 2021. Identification of Lactobacillus strains capable of fermenting fructo-oligosaccharides and inulin. Beneficial Microbes. https://doi.org/10.3390/microorganisms9102020.
DOI: https://doi.org/10.3390/microorganisms9102020

Interpretive Summary: Bacteria that promote digestive health, known as probiotics, have become a popular part of our diet yet little is known about their interactions with the gut microbiome, the community of bacteria found in the large intestine; or prebiotics, non-digestible dietary fibers shown to promote the growth of beneficial bacteria. The bacterial species most commonly used as probiotics are bifidobacteria and lactobacilli, but not all of these bacteria can utilize prebiotics for production of health promoting molecules, including short-chain fatty acids (SCFA). SCFA have been shown to positively affect gut health through a variety of mechanisms, including serving as an energy source for human cells. Growth of 86 Lactobacillus strains on the commercial prebiotics fructo-oligosaccharides and inulin, which are vegetable fibers used as health promoting ingredients in foods, such as cereals, energy bars, beverages and protein supplements, were compared and evaluated for SCFA production. Under conditions that mimic the human colon, only six bacterial strains were able to grow on either prebiotic and produce SCFAs. This study is the first to report that these six Lactobacillus strains are capable of producing health-promoting SCFAs, and emphasizes that the ability to utilize prebiotics is dependent on the specific bacterial strain, as several strains within the same Lactobacillus species were unable to grow on commercial prebiotics. These results will allow for further development of food-grade lactic acid bacteria and prebiotics as health-promoting functional food ingredients.

Technical Abstract: Inulin and fructo-oligosaccharides (FOS) are well studied prebiotics reported to support the growth of Lactobacillus and Bifidobacterium strains. Fermentation of these prebiotics by lactic acid bacteria has been reported to result in production of short-chain fatty acids (SCFA) and potentially improve human digestive health. Utilization of prebiotics is strain specific, and this study screened a collection of 86 Lactobacillus strains for the ability to grow and produce SCFA when 1% inulin or fructo-oligosaccharides (FOS) were provided as the carbon source in batch fermentations. When grown anaerobically at 32 degrees C, ten Lactobacillus strains grew on both prebiotic substrates (OD600 = 1.2); while Lactobacillus coryniformis subsp. torquens B4390 was shown to grow only in the presence of inulin. When the growth temperature was increased to 37 degrees C, four of these strains were no longer able to grow on either prebiotic. Additionally, L. casei strains 4646 and B441, and L. helveticus strains B1842 and B1929 did not require anaerobic conditions for growth on both prebiotics. Short-chain fatty acid analysis was performed on cell-free supernatants, and the concentration of lactic acid produced by the ten Lactobacillus strains ranged from 73-205 mM; L. helveticus B1929 was shown to produce the highest concentration of acetic acid ~19 mM. L. paraplantarum B23115 and L. paracasei ssp. paracasei B4564 were shown to produce the highest concentrations of propionic (1.8 - 4.0 mM) and butyric (0.9 and 1.1 mM) acids from prebiotic fermentation. Results from this study identified L. paraplantarum B23115 and L. paracasei ssp. paracasei B4564 as potential candidates for use with FOS or inulin as synbiotics for the development of functional foods aimed to improve digestive health.