An acid/alkaline stress and the addition of amino acids induce a prolonged viability of Lactobacillus plantarum loaded into alginate gel

This study reports on the investigation on the effects of the conditions used throughout the step of biomass production on the survival of Lactobacillus plantarum loaded into alginate gels. L. plantarum was grown under different conditions (MRS or a laboratory medium–LB2–at acidic or alkaline pHs, with NaCl, phenols, vitamins or amino acids) and immobilized in sodium alginate; cell number was evaluated throughout the storage and death (δstand) and first-reduction times (δ) were calculated. The storage of alginate gels at 4 °C prolonged cell viability up to 60 days (ca. 20 days for cells produced in MRS and stored at 30 °C); however, a similar prolongation was achieved for cells produced in LB2 adjusted to pH 5.0 and 9.0 or added with amino acids (death time > 50–60 days).