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.

Song Huang,Gwénaël Jan,Julien Jardin,Yves Le Loir,Xiao Dong Chen,Chantal Cauty,Floriane Gaucher,Romain Jeantet

doi:10.3389/fmicb.2018.02548

Song Huang, Gwénaël Jan + Show 6 more

Open Access

https://doi.org/10.3389/fmicb.2018.02548

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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.

Highlights

Lactobacillus is a major genus of the lactic acid bacteria (LAB), a GRAS (Generally Recognized as Safe) and economically important bacterial group used in foods, beverages, or dietary supplements
Sweet whey in the concentration ranging from 5 to 30% dry matter sustained the growth of L. casei inoculated at 107 CFU/mL with a stationary phase approximately starting at 12 h and a final population close to 2 × 108 CFU/mL, for 5, 10, 20, and 30% sweet whey
Multi-tolerance being evidenced, as a result of L. casei BL23 growth in hyperconcentrated sweet whey, we investigated its tolerance toward spray drying, as this technique is reputed as a severe challenge for bacteria

Summary

Introduction

Lactobacillus is a major genus of the lactic acid bacteria (LAB), a GRAS (Generally Recognized as Safe) and economically important bacterial group used in foods, beverages, or dietary supplements. Lactobacillus casei is a facultative heterofermentative species usually used as a starter culture for milk fermentation and for the maturation of cheeses in the food industry (Hammes and Hertel, 2006). Its surface-exposed components were proposed to take part in interactions with the intestinal mucosa (Muñoz-Provencio et al, 2011; Qin et al, 2017), in inhibition of Staphylococcus aureus internalization (Bouchard et al, 2013; Souza et al, 2017), and in the metabolism of human milk oligosaccharides, which plays a key role in establishing and maintaining the infant gut microbiota (Bidart et al, 2015). Excreted microvesicles carry key protein probiotic effectors of L. casei BL23 (Rubio et al, 2017) Consumption of L. casei BL23 modulates the microbiota in favor of Lactobacillaceae, Porphyromonadaceae, and Comamonadaceae (Yin et al, 2014)

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