Influence of commercial inactivated yeast derivatives on the survival of probiotic bacterium Lactobacillus rhamnosus HN001 in an acidic environment

Abstract

This study evaluated the influence of three inactivated yeast derivatives (IYDs) used in wine production, namely OptiRed®, OptiWhite® and Noblesse®, on the viability of the probiotic strain Lactobacillus rhamnosus HN001 in an acidic environment. Addition of the IYDs at 3 g/L significantly enhanced the survival of the probiotic bacteria by 2.75–4.05 log cycles after 10-h exposure in a pH 3.0 buffer. Acid stress assay with IYD components obtained after centrifugation and filtration revealed that water-soluble compounds were responsible for improving the acid tolerance of L. rhamnosus HN001 for all three preparations. Differences in protective effect amongst the IYDs on L. rhamnosus HN001 were observed when permeates and retentates of the water-soluble extracts, obtained through ultrafiltration with a 2 kDa membrane, were assayed against the lactic acid bacterium. Chemical analysis of the water-soluble components suggests that low molecular weight polysaccharides, specific free amino acids and/or antioxidants in the 2 kDa permeates could have contributed to the enhanced survival of L. rhamnosus HN001 during acid stress. The contrast amongst the 2 kDa retentates’ viability enhancing property may have been attributed to the differences in size and structure of the higher molecular weight carbohydrates and proteins, as the survival of the probiotic did not relate to the concentration of these compounds. These results suggests that oenological IYDs could potentially be applied to probiotic foods for enhancing the acid tolerance of the beneficial microorganisms, and consequently prolonging the shelf life of these products.Electronic supplementary materialThe online version of this article (doi:10.1186/s13568-017-0456-4) contains supplementary material, which is available to authorized users.

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“…The potential of mixed microbiomes in fermented products has been hypothesized to be part of their benefits, and possibly why single strains of probiotics may be less effective (Ouwehand et al 2018). Several studies showed that yeast could positively interact with probiotic bacteria by enhancing their survival and stimulating their growth (Chan et al 2019;Suharja et al 2014;Toh and Liu 2017). The positive effects of yeast might be attributed to the production of nutrients such as peptides, amino acids, and/or vitamins.…”