Catechins are a group of polyphenolic compounds that are antioxidants having beneficial biological activities. There are four main catechins in green tea, and each has its own biological features. In order to fully exploit prominent biological activities of specific catechins and to develop new medicine from catechins, it is necessary to obtain pure catechin preparations by isolation from natural sources, by chemical synthesis, or by biotransformation reactions with high yield and specificity. In this study epigallocatechin gallate (EGCG) can be hydrolyzed to epigallocatechin (EGC) by a hydrolase from Aspergillus oryzae after induction by addition of EGCG to the cultures. However, cultures without EGCG induction did not show any EGCG hydrolysis activity. The yield of EGC could reach at least 70%. Thin layer chromatography and high performance liquid chromatography were applied to separate and quantify EGCG and EGC.

草酸脱羧酶是一种含锰的酶，在白腐菌中广泛存在，少数低等真菌和细菌中也能产生。目前，至少十多种草酸脱羧酶得到了分离和纯化。该酶是一种氨基酸残基在379个左右的单体酶，一般都为酸性糖蛋白，含有2个锰离子，形成2个活性区域；表面一些氨基酸被不同程度地糖基化。晶体结构和其它一些波谱学研究解释了其空间结构和可能的电子传递机制。运用PCR技术和cDNA文库技术，越来越多的草酸脱羧酶基因被克隆。已研究的该酶基因中都含有17个左右的内含子，这些内含子在活性域位置上有比较高的保守性。一些特殊氨基酸序列的存在决定了该酶的表达形式为诱导型，菌株的基因调控序列中含有一段受草酸化合物作用的序列。该酶在一些酵母和植物等异源表达系统中有成功表达的报道。该酶的应用主要集中在以下几方面：造纸废水中的草酸盐降解；食品中的草酸降解；草酸生物检测（如临床诊断）等。

Catechins are antioxidants known to exhibit beneficial biological activities. Five main catechins are found in green tea and each catechin has its own biological features. In order to fully exploit prominent biological activities of specific catechins and to develop new pharmaceuticals based on catechins, it is necessary to obtain pure catechin preparations by isolation from natural sources, or by chemical synthesis, or by biotransformation reactions with high yield and specificity. This study shows that epigallocatechin gallate (EGCG) can be hydrolysed to epigallocatechin (EGC) by a hydrolase produced by Aspergillus niger after induction by addition of EGCG to the fungal cultures. Cultures without EGCG induction and cultures, to which olive oil had been added as an inducer, did not show any EGCG hydrolysis activity. The yield of EGC could reach at least 56%. Methods based on thin-layer chromatography and high performance liquid chromatography, were used for separation and quantification of EGCG and EGC. Enzymatic conversion is an environmentally friendly and efficient approach to produce non-ester catechins.

细菌纤维素是一种天然的生物高聚物，具有生物活性、生物可降解性、生物适应性，具有独特的物理、化学和机械性能，例如高的结晶度、高的持水性、超细纳米纤维网络、高抗张强度和弹性模量等，因而成为近年来国际上新型生物医学材料的研究热点。概括细菌纤维素的性质、研究历史以及在生物医学材料上的应用，重点阐述细菌纤维素在组织工程支架、人工血管、人工皮肤和治疗皮肤损伤方面的应用以及当前研究现状。

细菌纤维素是一种新型微生物合成材料，在食品、造纸、纺织、生物医药、声学器材振动膜和功能复合材料等方面均有很好的应用前景。细菌纤维素发酵培养基（尤其碳源）的成本是现今制约细菌纤维素推广应用的主要因素之一。甘露醇、果糖和葡萄糖等合成培养基所用碳源因其价格较高仅适用于实验室研究和小型发酵生产，规模化生产细菌纤维素的潜在原料应是一些量大价低的天然原料，包括水果类原料、糖质原料、低值淀粉类原料和废弃纤维素类原料等。木质纤维素原料是最具发展潜力的细菌纤维素碳源，也是细菌纤维素产业的根本出路，但目前存在一些技术瓶颈，制约了其开发利用，是一远期战略目标。文章简要介绍了细菌纤维素的基本情况，系统阐述了国内外发酵生产细菌纤维素原料的研究进展，展望了今后的发展趋势。