Background： Bacterial cellulose (BC) is a nanostructured material with unique properties and wide applicability. In order to decrease the production cost of bacterial cellulose, lignocellulose-based media have considerable potential as alternative cost-effective feedstocks. However, pretreatment and enzymatic hydrolysis of lignocellulose to sugars also generate fermentation inhibitors. Detoxification of lignocellulosic hydrolysates is needed to achieve efficient production of BC. In this investigation, different methods for detoxification of spruce hydrolysate prior to production of BC were compared with respect to effects on potential inhibitors and fermentable sugars, sugar consumption, BC yield, and cell viability. The objectives were to identify efficient detoxification methods and to achieve a better understanding of the role played by different inhibitors in lignocellulosic hydrolysates. Results： In a first series of experiments, the detoxification methods investigated included treatments with activated charcoal, alkali [sodium hydroxide, calcium hydroxide (overliming), and ammonium hydroxide], anion and cation ion-exchange resins, and reducing agents (sodium sulfite and sodium dithionite). A second series of detoxification experiments included enzymatic treatments (laccase and peroxidase). The potential inhibitors studied included aliphatic acids, furan aldehydes, and phenolic compounds. The best effects in the first series of detoxification experiments were achieved with activated charcoal and anion exchanger. After detoxification with activated charcoal the BC yield was 8.2 g/L, while it was 7.5 g/L in a reference medium without inhibitors. Treatments with anion exchanger at pH 10 and pH 5.5 gave a BC yield of 7.9 g/L and 6.3 g/L, respectively. The first series of experiments suggested that there was a relationship between the BC yield and phenolic inhibitors. Therefore, the second series of detoxification experiments focused on treatments with phenol-oxidizing enzymes. The BC yield in the laccase-detoxified hydrolysate reached 5.0-5.5 g/L after 14 days cultivation, which demonstrated the important inhibitory role played by phenolic compounds. Conclusions： The investigation shows that detoxification methods that efficiently remove phenolics benefit bacterial growth and BC production. Negative effects of salts could not be excluded and the osmotolerance of Gluconacetobacter xylinus needs to be further investigated in the future. Combinations of detoxification methods that efficiently decrease the concentration of inhibitors remain as an interesting option. ___________________________________________________ http://www.microbialcellfactories.com/content/12/1/93 http://www.microbialcellfactories.com/content/pdf/1475-2859-12-93.pdf

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.

A new carbon source for bacterial cellulose production was successfully developed from konjac powder by using dilute acid hydrolysis and was detoxified by different alkaline treatment methods to remove microbial growth inhibitors. The various treatments included the addition of calcium hydroxide or sodium hydroxide to pH 10, and subsequent adjustment of the pH to 5 with acid as well as treatment with activated charcoal or laccase, respectively. The results showed that the detoxification effect using Ca(OH)2 was much better than that using NaOH. If activated charcoal or laccase was added in the process, the detoxification effects would go further and bacterial cellulose production could be improved more. Based on the same concentration of total sugars, bacterial cellulose production using the hydrolyzates was 3 times higher than that using glucose, 6 times higher than that using mannose, and 5 times higher than that using glucose-mannose mixture as carbon source in static cultures. The addition of extra calcium in glucose media in the form of CaCl2 at pH 5 did result in an improvement of less than 50% in BC production, which was not comparable to the Ca(OH)2 treatments at pH 10. The possible mechanisms behind the findings were discussed and potential stimulatory factors for the fermenting bacterium formed during the alkaline processing deserve further attention. The results indicate that konjac powder could serve as a feedstock for bacterial cellulose production and cultivation of Amorphophallus rivieri Durieu would bring more economic benefits to farmers in future.