Importance and Evaluation of Glutamic Acid Production from Mostly Common Probiotic

This study aimed to estimate glutamic acid (Glu) production by probiotic bacteria and evaluate the impact of stimulants.70 samples, including raw milk, cottage cheese, yogurts, and commercial yogurts were used. Bacillus subtilis and Enterococcus faecium were identified as the main probiotic bacteria. Out of 70 samples, 7 strains from E. faecium and only one strain from B. subtilis were obtained by cultural methods and confirmed by PCR using specific primers. LC-MS/MS was used to estimate Glu production qualitatively, with three E. faecium and one B. subtilis strain showing the highest peak areas, which were then analyzed by DNA sequencing for molecular identification. Extracellular cellular glutamic acid (ECG) and Intracellular glutamic acid (ICG) production from the untreated selected strains was performed quantitatively using the LC-MS/MS technique. Stimulation of Glu-responsible genes was performed using sucrose-supplemented medium and UV light exposure. Results showed that stimulation by UV light showed the most effective approach for both ECG and ICG in the case of B. subtilis and for ICG in the case of E. faecium, as indicated by the increase in the produced quantity if compared to the standard formulation (using glucose) or sucrose supplementation, while sucrose supplementation showed effectiveness on ECG production in the case of E. faecium. From this study, it can be concluded that UV light exposure to B. subtilis and sucrose supplementation medium for E. faecium have optimum effect on the safe and economic production of Glu.