The Ability of Riboflavin-Overproducing Lactiplantibacillus plantarum Strains to Survive Under Gastrointestinal Conditions

HERNÁNDEZ-ALCÁNTARA, ANNEL M.; PARDO, SANDRA; MOHEDANO, MARI LUZ; VIGNOLO, GRACIELA M.; DE MORENO DE LEBLANC, ALEJANDRA; LEBLANC, JEAN GUY; AZNAR, ROSA; LÓPEZ, PALOMA

Frontiers in Microbiology

Frontiers Media

Año: 2020 vol. 11

Riboflavin, vitamin B2, is essential for humans and has to be obtained from thediet. Some lactic acid bacteria (LAB) produce this vitamin, and they can be usedfor in-situ fortification of foods. This could be an alternative to supplementation withchemically synthesized vitamin, to palliate riboflavin deficiencies in specific groups ofpeople. Moreover, if the producing LAB could survive in the gastrointestinal stress(GIT) they could be added as probiotics in this environment. In the present study wetested two riboflavin-overproducing Lactiplantibacillus plantarum strains (M5MA1-B2and M9MG6-B2), spontaneous mutants of LAB isolated from chicha, a traditionalAndean beverage. These two LAB, and also their isogenic strains M5MA1-B2[pRCR12]and M9MG6-B2[pRCR12], expressing the mCherry protein from the pRCR12 plasmid,were evaluated in vitro under simulated GIT conditions. Among other, specificallydeveloped protein fluorescence assays were used. The four LAB showed similar levelsof adhesion (>6.0%) to Caco-2 cells, higher than that of the probiotic Lacticaseibacillusrhamnosus GG strain (4.51%). Thus, LAB biofilm formation was assessed in the labeledcells by intracellular mCherry fluorescence and in the unlabeled parental strains bycrystal violet staining. Both methods detected the formation of consistent biofilms bythe L. plantarum strains. The quantification of mCherry fluorescence was also usedto analyze LAB auto-aggregation properties. High levels of auto-aggregation weredetected for both M5MA1-B2[pRCR12] and M9MG6-B2[pRCR12]. Survival of LABincluded in a commercial cereal-based food matrix (Incaparina) under GIT conditionswas also evaluated. The four LAB were resistant in vitro to the stomach and intestinalstresses, and proliferated in this environment, indicating a protective and nutritionaleffect of the Incaparina on the bacteria. Also, M9MG6-B2 survival in the presenceor absence of Incaparina was evaluated in vivo in a BALB/c mouse model. Theadministration of the M9MG6-B2 strain alone or together with Incaparina had no adverse effect on the health, growth and/or well-being of the rodents. In addition,an increment in the villus length/crypt depth ratio was observed. The overall resultsobtained indicate that the LAB studied have probiotic characteristics of interest for thedevelopment of functional foods.