Nowadays, many researches have been made on gallotannin biodegradation and have gained great success in further utilization. Some of industrial applications of these findings are in the production of tannase, the biotransformation of tannic acid to gallic acid or pyrogallol and detannification of food and fodder. Although ellagitannins have the typical C-C bound which is more difficult to be degraded than gallotannins, concerted efforts are still in progress to improve ellagitannin degradation and utilization. Currently, more attention is mainly focused on intestinal microflora biodegradation of tannins especially ellagitannins which can contribute to the definition of their bioavailability for both human beings and ruminants. Also there have been endeavours to utilize the tannin-degrading activity of different fungi for ellagitannin-rich biomass, which will facilitate application of tannin-degrading enzymes in strategies for improving industrial and livestock production. Due to the complicated structures of complex tannins and condensed tannins, the biodegradation of them is much more difficult and there are fewer researches on them. Therefore, the researches on the mechanisms of gallotannin and ellagitannin biodegradation can result in the overall understanding to the biodegradation of complex tannins and condensed tannins. Biodegradation of tannins is in an incipient stage and further studies have to be carried out to exploit the potential of various tannins for largescale applications in food, fodder, medicine and tannery effluent treatment.
Cypermethrin (CY) and its metabolite, 3-phenoxybenzoic acid (3-PBA), generally coexist in agricultural soil and cause a toxic effect on the human body. In this study, CY and its metabolite 3-PBA were simultaneously degraded by the cooperation of Bacillus licheniformis B-1 and Sphingomonas sp. SC-1. The effects of the inoculation proportion and inoculation method of these two strains, cultivation time, and initial CY content on the degradation of CY and 3-PBA were investigated. Furthermore, the degradation of CY and 3-PBA in soil environment by using the cooperation of these two strains was also determined. When the inoculation proportion of the biomass of strain B-1/strain SC-1 was 3.3:6.7, strain B-1 was inoculated first, and strain SC-1 was inoculated after 24 h of cultivation, 75.60% CY (100 mg L(-1)) was degraded at 72 h and the 3-PBA content was 10.31 mg L(-1). Compared with those by using only strain B-1, the half-life of CY by using these two strains was shortened from 71.90 to 35.71 h, and the yield coefficient of 3-PBA was decreased from 0.8938 to 0.2651. As in the soil environment, the CY content by using these two strains within a period of 25 days declined from 22.71 to 5.33 mg kg(-1) and the 3-PBA content was 1.84 mg kg(-1). Compared with those by using only strain B-1, the half-life of CY by using these two strains was shortened from 19.86 to 11.34 days and the yield coefficient of 3-PBA was decreased from 0.5302 to 0.2056. This work could develop a promising approach for the simultaneous degradation of CY and its metabolite 3-PBA in agricultural soil.
HPLC and spectrophotometric methods were developed for the determination of total catechins in tea extracts. A comparison was made of the two methods after validation. The HPLC method was carried out using a Hypersil ODS C(18) column and a methanol-0.2% acetonitrile gradient elution. This method showed good resolution of individual catechins, and was found to be precise for the quantification of total catechins (summed individual catechins). The spectrophotometric method was used to monitor the change in absorbance that occurs during the reaction between catechins and vanillin-HCl reagents. The determining wavelength was confirmed as 505 nm, where the catechin-vanillin complex showed peak absorbance. The developed spectrophotometric method performed with varying results, when three calibration curves, respectively based on catechin (C), epicatechin (EC) and epigallocatechin gallate (EGCG), were employed. The C and EC calibration curves resulted in decreased contents of total catechins, while the EGCG calibration curve led to results equivalent to the HPLC assays above, suggesting that a proper choice of standard is necessary for the spectrophotometric determination of total catechins. The two methods can be used for the routine determination of total catechins in catechin-containing products.
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