Growth medium Pi concentration affects stress resistance and metabolic traits of Lactiplantibacillus plantarum CRL 1905

ARAOZ MARIO; GRILLO-PUERTAS MARIANA; HEBERT ELVIRA MARÍA; VILLEGAS JOSEFINA MARÍA; RAPISARDA VIVIANA ANDREA

Mendoza

Congreso; Reunión anual Edición LVIII Sociedad Argentina de Investigaciones Bioquímicas; 2022

Lactic acid bacteria (LAB) are a group of microorganisms that have multiple biotechnological applications. LAB used in food production or as probiotics are subjected to harsh conditions derived from industrial processes or from the passage through the gastrointestinal tract. Thus, stress adaptation and survival play a crucial role in the robustness of strains. Polyphosphate (polyP) is a linear polymer formed by orthophosphate (Pi) residues, which is involved in response to stressful conditions in bacteria. The ability of Lactiplantibacillus plantarum CRL 1905 to maintain high levels of polyP in stationary phase was previously evidenced in a chemically defined medium (CDM) containing high Pi content (60 mM). In this condition, cells showed an increased viability through time, as well as an up-regulation of proteins involved in the main metabolic pathways, indicating an improved metabolism in late stationary phase. The aim of this study was to evaluate whether media Pi concentration affects metabolites production and stress resistance in L. plantarum CRL 1905. A HPLC analysis on supernatants obtained from cells grown for 24 and 48 h in CDM supplemented with 2 and 60 mM of Pi (CDM-P and CDM+P, respectively) was carried out, showing a higher lactic acid accumulation, as well as a faster glucose consumption by cells grown in the high Pi condition when compared to those grown in CDM-P. In addition, 48 h-cells grown in both media were subjected to several stressors (NaCl, H2O2, freeze-drying, and gastrointestinal tract simulation solutions). In all cases, an enhanced survival of the cells grown in high Pi medium in respect to those grown in CDM-P was observed. The intracellular polyP levels in CDM+P decreased after the exposure to different stressors, an already known survival strategy for bacteria. It is worth to mention that after freeze-dried process, CDM+P cells maintained their antimicrobial activity against pathogenic bacteria. Our results demonstrate that variations in media Pi concentration alter the production of mains organic acids and resistance to different stressful conditions in CRL 1905 strain.