Screening of components to optimize a low-cost culture media for calves' lactic acid bacteria, their resistance to spray dried and storage.

Veterinary probiotic formulations require high numbers of viable bacteria and culture media that support efficient biomass production while being economically feasible. The aim of this work was to optimize a culture medium for 4 homologous probiotic lactic acid bacteria (BAL) strains (Lactobacillus johnsonii-CRL1693, Ligilactobacillus murinus-CRL1695, Limosilactobacillus mucosae-CRL1696, and Ligilactobacillus salivarius-CRL1702) isolated from fecal samples of calves and to evaluate their resistance to spray dried and storage conditions. Sixty culture media designed containing different carbon source (glucose, fructose, molasses, pectin, lactose and corn-syrup) and three commercial yeast extracts (YE) were evaluated at 30 °C-37 °C. Glucose replacement was feasible for most strains, except with pectin. Glucose and lactose were optimal for CRL1693, CRL1695, and CRL1696, while for CRL1702 only fructose. All the strains tolerated spray drying, except CRL1702 that was deeply affected. The resulting powders maintained suitable viability, moisture content, and water activity during storage, and SEM revealed no differences in bacterial morphology between cells grown in the optimized and control media. Replacing glucose with molasses and using Angel YE reduced the estimated culture-medium cost, demonstrating the economic potential of the optimized formulations. Overall, the optimized media provided economical alternatives for the production of biomass of BAL intended for veterinary probiotic applications.