Biodegradation of tannic acid by Citrobacter freundii isolated from a tannery effluent.


A bacterial strain capable of utilizing tannic acid as sole carbon source was isolated from the effluent of a tannery and was identified as Citrobacter freundii. This organism could grow at concentrations as high as 5% (w/v) of tannic acid and produced extracellular tannase to hydrolyze the same. When grown in minimal medium containing 1% tannic acid (w/v) at 30 degrees C, this strain produced 1.87 U/ml of tannase at 6 h. At that time, tannic acid degradation products, namely glucose and gallic acid, were detectable in the culture filtrate; the other intermediate metabolites formed were pyrogallol (extracellular) and pyruvate (intracellular). 2-hydroxymuconic acid is presumed to form as a result of ortho-cleavage of pyrogallol. The proposed biochemical pathway for the degradation of tannic acid by Citrobacter freundii is: Tannic acid-->[Glucose + Gallic acid]-->Pyrogallol -->2-hydroxymuconic acid -->[?]-->Pyruvate.


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@article{Kumar1999BiodegradationOT, title={Biodegradation of tannic acid by Citrobacter freundii isolated from a tannery effluent.}, author={R. Ashok Kumar and Paramasamy Gunasekaran and Manikandan Lakshmanan}, journal={Journal of basic microbiology}, year={1999}, volume={39 3}, pages={161-8} }