Aerobic and anaerobic degradation of tannic acid on water samples from Monjolinho reservoir (São Paulo, SP, Brazil)

Abstract

In order to describe the transformations of tannic acid during its degradation (under aerobic and anaerobic conditions) incubations were performed. To evaluate the oxygen consumption, the tannic acid was added to 1 L of water sample from Monjolinho's reservoir (22º00'S and 47º54'W); these solutions were aerated and the dissolved oxygen was monitored for 16 days, the anaerobic process was avoided. For the anaerobic and aerobic degradation, the dissolved organic carbon and the acid tannic concentrations were estimated on the samples days. The results were fitted to first-order kinetic model, being possible to verify that during the 16 days the oxygen uptake was 3.6 mg.L -1 , the deoxygenation rate (k D ) of this process was 0.39 day -1 . The degradation coefficients were calculated through the decay of the tannic acid and organic carbon concentrations. In the aerobic process, the global decay coefficient (k G ) was 0.36 day -1 and in the anaerobic 0.28 day -1 . Overall, the obtained degradation coefficients suggest that the bacterioplankton of the Monjolinho's reservoir possess a high capacity of polyphenols degradation.Key words: oxygen uptake, aerobic mineralization, anaerobic mineralization, tannic acid, Monjolinho Reservoir (UFSCar, São Carlos, SP). RESUMO

Isolation and Characterization of Tannic Acid Hydrolysing Bacteria from Soil

“…The ester and depside bonds of hydrolysable tannins are broken down by enzyme tannase (tanninacyl hydrolase) to give product gallic acid and glucose [6]. The gallic acid monomers are utilised as substrates by oxidative breakdown to simple aliphatic acids, which then enter the citric acid cycle.…”

“…In addition to that fungal strains are difficult to manipulate genetically because of their complexity. Tannase produced by bacteria can degrade tannic acid and also natural tannins like chestnut, tara, oak and myrobalan tannins [6][7][8][9]. Although a number of tannin-degrading micro-organisms which are potential sources of tannase have been reported [10], the search continues for organisms which are more prolific degraders of tannins and better sources of tannase.…”