EPS Production by Lacticaseibacillus casei Using Glycerol, Glucose, and Molasses as Carbon Sources

Abstract

This study demonstrates that <i>Lactobacillus</i> can produce exopolysaccharides (EPSs) using alternative carbon sources, such as sugarcane molasses and glycerol. After screening 22 strains of Lactobacillus to determine which achieved the highest production of EPS based on dry weight at 37 °C, the strain Ke8 (<i>L. casei</i>) was selected for new experiments. The EPS obtained using glycerol and glucose as carbon sources was classified as a heteropolysaccharide composed of glucose and mannose, containing 1730 g.mol^-1, consisting of 39.4% carbohydrates and 18% proteins. The EPS obtained using molasses as the carbon source was characterized as a heteropolysaccharide composed of glucose, galactose, and arabinose, containing 1182 g.mol^-1, consisting of 52.9% carbohydrates and 11.69% proteins. This molecule was characterized using Size Exclusion Chromatography (HPLC), Gas chromatography-mass spectrometry (GC-MS), Fourier-transform infrared spectroscopy (FTIR), and proton nuclear magnetic resonance spectroscopy (¹H-NMR). The existence of polysaccharides was confirmed via FT-IR and NMR analyses. The results obtained suggest that <i>Lacticaseibacillus casei</i> can grow in media that use alternative carbon sources such as glycerol and molasses. These agro-industry residues are inexpensive, and their use contributes to sustainability. The lack of studies regarding the use of <i>Lacticaseibacillus casei</i> for the production of EPS using renewable carbon sources from agroindustry should be noted.