The Study Of Inhibition Effects Of Black Wattle Tannin On Microorganisms

Black wattle bark extract consists of a series of polyphenolic compounds with a board range of molecular weight distribution and a considerable amount of non-tannin components. Being treated with alcohol, tannin purity of the extract increases by 18% and reaches 82%. Various fractions of tannins with different polarities and relatively narrow molecular weight distribution were obtained by extractions using ether and ethyl acetate separately. The study shows that the ethyl acetate fraction, which has a relatively lower molecular weight, has a better performance in the inhibition effect on microorganisms.The chemical degradation of black wattle tannin is studied in this thesis, a new method is used to degrade the tannin. The degradation product, which was treated by 10ml hydrogen peroxide and has a average molecular weight of 898 Dalton, has a better inhibition effect on microorganisms even than the ethyl acetate fraction.Biodegradation of black wattle tannin using epiphyte is also studied in order to obtain a product with a better inhibition ability, however, the result shows that the degradation has no inhibition effect on microorganisms at all, a further study shows that the degradation product has a much lower weight than before degradation, and also has a much few hydroxides. It speculates that the tannin has both an auto condensation and biodegradation when treated by epiphyte.Through the above-mentioned study, it speculates that the molecular weight plays an important role in the inhibition ability. So the effects of different tannin fractions with different molecular weight are studied on protein, enzymes and protein inner the epiphyte. The results show that a moderate molecular weight of tannin has a greatest effect on the protein inner epiphyte, which can explain the better performance of the ethyl acetate fraction.