HPLC Characterization of Lactic Acid Formation and FTIR Fingerprint of Probiotic Bacteria during Fermentation Processes

Abstract

Lactic acid production during growth of several probiotic bacteria (Lactobacillus plantarum, Bifidobacterium infantis, Lactobacillus casei, Bifidobacterium breve and mix of them) in model MRS media has been monitored using HPLC and the bacterial fingerprint was detected using FTIR. FTIR spectroscopy was able to fingerprint the bacteria identify specific markers located at 900-1300 cm-1 (carbohydrates and proteins, nucleic acids from DNA of bacteria), 1300-1900 cm-1 (C=O stretching vibrations) and large band (for water) at 3100-3700 cm-1. HPLC evaluation showed that Lactobacillus plantarum achieved lactic acid concentration (after 78 h of fermentation) close to 6.08g L-1, Bifidobacterium infantis 7.09 g L-1, Lactobacillus casei 6.16 g L-1, Bifidobacterium breve 6.17 g L-1, while mix of them 7.12 g L-1. Pearsons analysis showed that the level of lactic acid in mix of probiotics bacteria was positively and significantly correlated, with lactic acid level of Lactobacillus plantarum (r2=0.965), Bifidobacterium infantis (r2=0.9846), Lactobacillus casei (r2=0.9904), Bifidobacterium breve (r2=0.9958), when P<0.0001.