Statistical optimization of exopolysaccharide production by Lactobacillus plantarum NTMI05 and NTMI20

In this study, 27 strains of Lactic acid bacteria (LAB) were isolated and identified from different milk sources. All the isolates were biochemically characterized and screened for their ability to produce exopolysaccharides (EPS), among which two isolates namely Lactobacillus plantarum NTMI05 (197 mg/L) and Lactobacillus plantarum NTMI20 (187 mg/L) showed higher EPS production. Both the isolates were molecular characterized and tested for their probiotic properties. The chemical composition of EPS from L. plantarum NTMI05 and NTMI20 revealed the presence of 95.45% and 92.35% carbohydrates, 14 ± 0.1and 11 ± 0.15 mg/L lactic acid, 10.5 ± 0.2 and 9 ± 0.1 mg/mL of reducing sugar, respectively. HPLC analysis showed galactose at the retention time of 2.29.The maximum EPS yield was optimized for the media components like glucose (20 g/L), yeast extract (25 g/L) and ammonium sulphate (2 g/L) using Central Composite Design and Response Surface Methodology (RSM). Under optimum conditions the predicted maximum EPS production was 0.891 g/L, 0.797 g/L, while the actual experimental value was 0.956 g/L and 0.827 g/L for L. plantarum NTMI05 and NTMI20, respectively. The antioxidant capacity was also evaluated by DPPH and reducing power assay proving the potentiality of these organisms in food and dairy industries.