Tannic acid degradation potential and biochemical characterization of Paenibacillus lautus BCA501 isolated from the gut of Silver therapon (Leiopotherapon plumbeus)

Microbial degradation of tannic acid offers significant potential for mitigating the negative effects of tannins while enabling various biotechnological applications. In this study, Paenibacillus lautus BCA501, isolated from the gut of the Silver therapon (Leiopotherapon plumbeus), is reported for the first time as a tannic acid-degrading bacterium. The strain effectively utilized tannic acid for growth, achieving a biomass yield coefficient (Y_X/S) of 1.30 g_biomass per g_substrate at 2 g/L tannic acid, which decreased to 0.594 g_biomass per g_substrate at 10 g/L. Kinetic analysis revealed a maximum growth rate of 0.562h^-1, with substrate inhibition at 11.26 g/L based on the Monod model. Tannase activity, though growth-associated, declined from 0.300 to 0.046 U/mL with increasing substrate concentration. Despite this reduction, gallic acid release increased significantly, with its growth-associated production coefficient peaking at 2.22 g/L at 10 g/L tannic acid, demonstrating efficient hydrolysis into phenolic compounds. This study provides the first evidence of tannic acid degradation by Paenibacillus lautus underscoring its potential for microbial tannase production and phenolic biotransformation.