BEER BAGASSE-ENRICHED MEDIUM IMPROVES BIOMASS PRODUCTION OF PROBIOTIC Lactobacillus johnsonii CRL2240

BABOT J. D.; OBREGOZO M.; ANDRADA E.; MEDINA R.; LEBLANC, J. G.

San Miguel de Tucumán

Simposio; VI International Symposium on Lactic Acid Bacteria - I Argentinean-Japanese Lactic Acid Bacteria ?Tohoku Forum for Creativity? Meeting; 2024

Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Referencia para Lactobacilos

Ferulates play an important role in inhibiting ruminant digestion of plant cell walls. Therefore, the ferulic acid esterase-producing Lactobacillus johnsonii CRL2240 has been studied as a silage inoculant and goat probiotic. In order to perform farm-scale experiments, a cost-effective conservation strategy must be developed, for which biomass production is the first step. Cultures of this strain in MRS or LAPTg broths normally reach sub-optimal counts for a conservation process (2×10^8 CFU/mL). Therefore, the aim of this work was to design a low-cost, animal protein-free medium that allows a higher biomass yield of L. johnsonii CRL2240. To this end, protein or fiber-rich industrial by-products were used. L. johnsonii CRL2240 was inoculated into different culture media, incubated at 37°C, and CFU/mL and pH of the cultures were determined at regular intervals. The following culture media and incubation conditions were tested: 1) LAPTg broth, static, free pH; 2) MM broth (containing texturized soybean flour), static, free pH; 3) MM broth, with stirring (75 rpm), free pH; 4) MM broth, with stirring (75 rpm), pH fixed at 6.50; 5) MM broth + FeSO4, static, free pH; 6) BSG broth (containing beer bagasse) with 1.5% yeast extract, static, free pH; 7) BSG broth with 1% yeast extract, static, free pH; and 8) BSG broth with 1% yeast extract, centrifuged, static, free pH. Counts reached 2×10^8 CFU/mL and pH 4.3 at 8 h when biomass was produced in LAPTg broth, while growth in MM broth in a bioreactor with stirring or without it led to similar counts but lower pH (3.8) for the latter condition. Similar results were obtained by adding FeSO4 to MM broth, although cultures reached the stationary phase after only 4 h of incubation. Remarkably, counts rose to around 1×10^9 CFU/mL and pH reached 3.8 after 6 h in BSG with 1.5% yeast extract. To further lower the cost of the broth, yeast extract concentration was reduced to 1% without affecting biomass production. Finally, eliminating excess beer bagasse flour by centrifugation after autoclaving BSG broth led to similar cell counts and pH results. In conclusion, a low-cost, animal protein-free broth where L. johnsonii CRL2240 reaches counts four times higher than LAPTg broth (1×10^9 vs 2×10^8 CFU/mL), and in a shorter incubation time, was designed. Moreover, a valorization of a residue of the beer industry is described.