Enterobacter hormaechei Z8b-60: A Tannin Degrading Bacteria Isolated from Slaughterhouse Waste

Tannases or Tannin acyl hydrolases (EC 3.1.1.20) are a family of esterases that catalyze the hydrolysis of ester and depside bonds present in hydrolyzable tannins to release gallic acid. Industrial applications of tannase in food, brewing, chemical, pharmaceutical, and bioremediation, have made it one of the most important enzymes in research. The aim of the present study focused on the degradation of tannic acid by novel bacterial tannase isolated from slaughterhouse waste-enriched soil. Soil containing ruminant microflora is cultured on MSM containing tannic acid. Among four bacterial isolates, a potent strain was cultivated for identification which are then analysed for biochemical characterization and physiological characterization. Bacteria use tannic acid as the sole carbon source for growth and showed maximum growth at 0.6%. The morphology of the isolate shows that it contains gram-negative rods that are nonmotile and capsulated. Based on 16S rRNA and phylogenetic analysis, the isolate was confirmed as Enterobacter hormaechei Z8b-60. Tannase production from bacteria was confirmed by a novel, sensitive plate assay by observing the zone of clearance around colonies and also by dye binding method using methyl gallate as substrate. During the study, TLC and HPLC were performed to analyze the accumulated gallic acid and other metabolites. Intracellular tannase production amplified from 14.98 U/mL to 102.7 U/mL as tannic acid concentration increases from 0.4% to 1.0%, respectively.