Characterization of Tannase Production by Lactococcus Lactis Subsp Lactis and its Potential in Enhancing Nutritional Value of a Composite Sourdough

Abstract

In foods, tannins are considered nutritionally undesirable. Composite sourdough batter prepared using vigna mungo flour and wheat flour (Bhanwar et al., 2013) makes it an attractive source for protein fortification and nutritional enrichment, however presence of antinutrients like tannins, phytic acid, saponin etc. hinder their utilization in human body. In the present study we report the tannin degradation ability of probiotic strain Lactococcus lactis subsp lactis. This strain was able to tolerate tannin concentration of 0.25 mM, tannin degradation occurred primarily by enzyme tannase and significant (p<0.05) degradation (44.2%) was observed at tannin concentration of 0.08mM, pH-6.8, temperature 37˚C and without agitation after 6 hours of fermentation in MRS media. Tannase production was inducible, was found to be thermostable and detected both intracellularly and extracellularly. Intracellular tannase showed higher activity in comparison to extracellular. As microorganisms undergo profound changes during their transition from planktonic organisms to cells that are part of a complex, surface-attached community. Therefore, we checked for biofilm development and results showed that there is more biofilm formation in presence tannin and biofilm formation was not affected due to the presence of tannin. In order to access the applicability of L. lactis, an experimental composite sourdough containing Vigna mungo and wheat flour was prepared. Fermentation was initiated by inoculating overnight culture of L. lactis followed by incubation at 37˚C for 4 hours. Analysis of sourdough extracts indicated a complete reduction of tannin (99.98%) the principal anti-nutrients in Vigna mungo. The result of this study suggests a potential applicability of L. lactis subsp lactis in degrading antinutrients, thus enhancing the nutritional value of traditional Indian composite sourdough. Keywords: Antinutrients, Sourdough, Vigna mungo, Biofilm, Tannin