Biodegradation of tannic acid by Citrobacter freundii isolated from a tannery effluent. |
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Authors: | R A Kumar P Gunasekaran M Lakshmanan |
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Institution: | Department of Microbial Technology, School of Biological Sciences, Madurai Kamaraj University, India. |
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Abstract: | 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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