Growth in Hyper-Concentrated Sweet Whey Triggers Multi Stress Tolerance and Spray Drying Survival in Lactobacillus casei BL23: From the Molecular Basis to New Perspectives for Sustainable Probiotic Production

Abstract

Lactobacillus casei BL23 has a recognized probiotic potential, which includes immune modulation, protection toward induced colitis, toward induced colon cancer and toward dissemination of pathogens. In L. casei, as well as in other probiotics, both probiotic and technological abilities are highly dependent (1) on the substrate used to grow bacteria and (2) on the process used to dry and store this biomass. Production and storage of probiotics, at a reasonable financial and environmental cost, becomes a crucial challenge. Food-grade media must be used, and minimal process is preferred. In this context, we have developed a “2-in-1” medium used both to grow and to dry L. casei BL23, considered a fragile probiotic strain. This medium consists in hyper-concentrated sweet whey (HCSW). L. casei BL23 grows in HCSW up to 30% dry matter, which is 6 times-concentrated sweet whey. Compared to isotonic sweet whey (5% dry matter), these growth conditions enhanced tolerance of L. casei BL23 toward heat, acid and bile salts stress. HCSW also triggered intracellular accumulation of polyphosphate, of glycogen and of trehalose. A gel-free global proteomic differential analysis further evidenced overexpression of proteins involved in pathways known to participate in stress adaptation, including environmental signal transduction, oxidative and metal defense, DNA repair, protein turnover and repair, carbohydrate, phosphate and amino acid metabolism, and in osmoadaptation. Accordingly, HCSW cultures of L. casei BL23 exhibited enhanced survival upon spray drying, a process known to drastically affect bacterial viability. This work opens new perspectives for sustainable production of dried probiotic lactobacilli, using food industry by-products and lowering energy costs.

Technological characterization of vaginal probiotic lactobacilli: resistance to osmotic stress and strains compatibility

“…), intracellular accumulation of polyphosphate of L. casei BL23 grown in hyper concentrated (30% dry matter) sweet whey (Huang et al . ), an increased synthesis of inorganic polymer polyphosphate, the role of Poly‐P as a molecule that modulates host‐signalling pathways (Alcántara et al . ) or the addition of poly‐Ƴ glutamic acid (Bhat et al .…”

“…) in high substrate concentration (Huang et al . ), or induced regulation of unsaturated fatty acid (Zhang et al . ), intracellular compatible solute pools (Tian et al .…”

“…Lactobacilli are the predominant bacteria in the healthy women vaginal microbiome being Lactobacillus gasseri, L. jensenii, L. crispatus and L. iners the species more frequently isolated (Huttenhower et al 2012). The use of probiotics as preventive or therapeutic agents is applied for women's health and constitutes a novel alternative.…”

Benefits and drawbacks of osmotic adjustment in Propionibacterium freudenreichii

“…The label free proteomics was have been conducted as Huang et al 2018 [41]. At the beginning of stationary phase, P. freudenreichii cells were harvested by centrifugation and washed twice with PBS buffer…”

The Inoculation of Probiotics In Vivo Is a Challenge: Strategies to Improve Their Survival, to Avoid Unpleasant Changes, or to Enhance Their Performances in Beverages

“…(a) pH modification to trigger acid adaptation [21,[26][27][28]: Probiotics are cultured in media adjusted to suboptimal pH (4.5-5.5) for several passages before inoculation in acid matrix (for example, fruit juices); (b) Osmoadaptation [29,30]: Microorganisms are grown in hyperosmotic media (for example, hyperconcentrated sweet whey) to trigger adaptation to drying; (c) Media supplementation with sugars (mannose, trehalose, sucrose) [31,32] to improve viability during freeze-drying; (d) Media supplementation with protective compounds (arginine, Tween 80, aspartate, gluthatione) [19,21] to improve acid resistance; (e) Media supplementation with prebiotics [33,34] generally increases viability throughout storage; (f) Starvation [28] for a general increase of viability during storage: Probiotics are cultured in media with a few nutrients (amino acids and/or sugar) before inoculation in food. This practice could increase viability during refrigerated storage; (g) Cold-adaptation [35]: Probiotics and/or starter strains are cultured at suboptimal temperatures (15-20 • C), thus increasing their technological performances in food; (h) Media supplementation with phenols (for example, vanillic acid) to improve strain viability in juices [26]; (i) Strain culturing in presence of increasing amount of the final food matrix [26]: Probiotics could be cultured in the presence of increasing amounts of juices (from 10% to 50%), thus increasing their viability in the product.…”