Expression and Immobilization of Tannase for Tannery Effluent Treatment from Lactobacillus plantarum and Staphylococcus lugdunensis: A Comparative Study.

Agro-industrial discharges have higher concentrations of tannins and have been a significant cause of pollution to water bodies and soil surrounding the agro-industries. So in this study, toxic tannic acid is into commercially valuable gallic acid from the tannery effluent using immobilized microbial tannase. Tannase genes were isolated from Lactobacillus plantarum JCM 1149 (tanLpl) and Staphylococcus lugdunensis MTCC 3614 (tanA). Further, these isolated tannese genes were cloned and expressed in BL 21 host using pET 28a as an expression vector,  and immobilized in sodium alginate beads. Vegetable tannery effluent was treated by tannase-immobilized beads at 25 °C and 37 °C, where liberated gallic acid was analyzed using TLC and NMR to confirm the tannin reduction. Further, both immobilized tannases exhibited excellent reusability up to 15 cycles of regeneration without significant reduction in their activity. Moreover, we also showed that immobilized tannases tanLpl and tanA activity remained unaffected compared to the free enzyme in the presence of metal ions. Further, tanA activity remained unaffected over a wide range of pH, and tanLpl showed high thermal stability. Thus, immobilized tannase tanLpl and tanA provide a possible solution for tannery effluent treatment depending upon industry requirements and reaction composition/effluent composition, one can choose a better-immobilized tannase among the two as per the need-based requirement.