黄孢原毛平革菌LIP-14酶液抑制CMP返黄的研究

前对各种木材腐朽真菌及其粗酶液抑制纸浆热返黄和提高纸浆白度的作用进行了评价，证实本实验室筛选的一株黄孢原毛平革菌木素过氧化物酶缺陷株LIP－14的胞外粗酶液的抑制效果最佳，其抑制率与国际上同类研究水平相当，本论进一步对该菌抑制返黄的各种影响因素进行了分析，并分别以纯化的木素和纸浆为研究对象，对酶液抑制返黄的作用机理进行了探讨，证实酶处理抑制返黄的作用是通过还原醌型化合物进行的。     

黄孢原毛平革菌固态发酵木薯渣生产锰过氧化物酶及其脱色靛蓝(英文)

Bioconversion of lignocellulosic wastes to higher value products through fungal fermentation has economic and ecological benefits. In this study, to develop an effective strategy for production of manganese peroxidase (MnP) from cassava residue by Phanerochaete chrysosporium in solid state fermentation, the stimulators of MnP produc-tion were screened and their concentrations were optimized by one-at-a-time experiment and Box–Behnken design. The maximum MnP activity of 186.38 nkat·g?1 dry mass of the sample was achieved after 6 days of fer-mentation with the supplement of 79.5 mmol·L?1·kg?1 acetic acid, 3.21 ml·kg?1 soybean oil, and 28.5 g·kg?1 alkaline lignin, indicating that cassava residue is a promising substrate for MnP production in solid state fermen-tation. Meanwhile, in vitro decolorization of indigo carmine by the crude MnP was also carried out, attaining the ratio of 90.18%after 6 h of incubation. An oxidative mechanism of indigo carmine decolorization by MnP was pro-posed based on the analysis of intermediate metabolites with ultra-high performance liquid chromatography and gas chromatography tandem mass spectrometry. Using the crude MnP produced from cassava residue for indigo carmine decolorization gives an effective approach to treat dyeing effluents.     

黄孢原毛平革菌降解偶氮染料的氮源调控及机理研究

利用黄孢原毛平革菌(Phanerochaete chrysosporium,PC菌),研究在氮源调控下,偶氮苯染料的降解过程,以及脱色率、TN、TOC和COD浓度等出水水质特性变化情况,初步分析了这些指标变化的内在关系;并由色谱检测结果简单分析了偶氮苯染料降解机理。结果表明:黄孢原毛平革菌对偶氮苯染料具有很好的脱色降解效果;在偶氮苯的降解中发生了偶氮键的断裂,生成了苯胺中间降解产物。     

黄孢原毛平革菌对大豆秸秆木质素降解的FTIR表征

研究黄孢原毛平革菌(Phanerochaete chrysosporium Burdsall)对大豆秸秆中木质纤维素的降解条件。结果显示：5g秸秆粉中添加合成培养液12mL、接种量为0.8mL(孢子悬液浓度8.6×106CFU/mL)、培养基初始pH4.5,发酵10d后,木质素降解率为45.96%。并采用傅里叶红外光谱分析(Fourier transform infrared spectroscopy,FTIR) 检测降解后秸秆中官能团的变化,发现与木质素相关的谱峰(1099cm-1、1057～1038cm-1)相对强度减小,与苯环相关的谱峰(1643～1608cm-1、1510～1508cm-1)相对强度增加,表明部分大分子木质素裂解成小分子木质素或木质素单体,对比其他谱峰相对强度的变化,发现木质素中苯环等环状化合物含量减少。     

固定化黄孢原毛平革菌木素过氧化物酶的研究

用大孔吸附树脂进行黄孢原毛平革菌来源的木素过氧化物酶固定化试验,筛选出固定化效果较好的XAD7HP大孔树脂,研究了其固定化条件。结果表明,当树脂1.0g,酶液pH4.5,加酶量87.2U,吸附温度25℃,吸附4h,戊二醛质量分数0.2%,戊二醛处理时间120min,可获得最佳的固定化效果,固定化酶活力可达到16U/g(对载体)。     

电场对黄孢原毛平革菌生长、细胞通透性及其胞外酶反应的影响

研究了交、直流电场对黄孢原毛平革菌Phanerochaete chrysosporuim的生长、细胞通透性及其所分泌的漆酶、木质素过氧化物酶及锰型过氧化物酶活力的影响. 结果表明,施加50 Hz, 50 mA交流电可显著地促进Phanerochaete chrysosporium的生长,经过10 d的培养,其干菌重为对照组的1.72倍;施加交、直流电都能够使细胞的通透性增强;施加交、直流电场在短时间内可显著提高3种胞外酶的活力,而时间过长则导致活力降低,电流强度为10 mA时的适宜加电时间为10 h.     

黄孢原毛平革菌产蛋白酶对过氧化物酶的影响

在培养黄孢原毛平革菌产生木质素过氧化物酶(LiP)和锰过氧化物酶(MnP)过程中产生的胞外蛋白酶与LiP和MnP的快速失活有关.该蛋白酶在pH 7的条件下酶活很高,其主要作用是促进LiP和MnP的分解,而不是抑制它们的产生.HgCl2是蛋白酶的抑制剂,其抑制机理类似于HgCl2对蛋白酶K(PK)的抑制.添加HgCl2的发酵液能提高过氧化物酶的酶活和稳定性,最佳添加量为1 μmol/L,最佳添加时间在接种后第5天.     

固定化黄孢原毛平革菌生产乙二醛氧化酶的研究

聚氨酯泡沫固定化黄孢原毛平革菌限碳培养能有效地生产乙二醛氧化酶,乙二醛氧化酶的底物丙酮醛、乙二醛等不能诱导乙二醛氧化酶的合成,藜芦醇、苯甲醇能诱导乙二醛氧化酶的合成。Mn2+浓度为2.96×10-5mol/L时活力最高,Fe2+、Cu2+对产量影响不大,空气中能合成乙二醛氧化酶,但效果不如通氧。在较优的培养条件下,乙二醛氧化酶活力为29.1U/L。     

Acetylated Xylan Degradation by Glycoside Hydrolase Family 10 and 11 Xylanases from the White-rot Fungus Phanerochaete chrysosporium

Endo-type xylanases are key enzymes in microbial xylanolytic systems, and xylanases belonging to glycoside hydrolase (GH) families 10 or 11 are the major enzymes degrading xylan in nature. These enzymes have typically been characterized using xylan prepared by alkaline extraction, which removes acetyl sidechains from the substrate, and thus the effect of acetyl groups on xylan degradation remains unclear. Here, we compare the ability of GH10 and 11 xylanases, PcXyn10A and PcXyn11B, from the white-rot basidiomycete Phanerochaete chrysosporium to degrade acetylated and deacetylated xylan from various plants. Product quantification revealed that PcXyn10A effectively degraded both acetylated xylan extracted from Arabidopsis thaliana and the deacetylated xylan obtained by alkaline treatment, generating xylooligosaccharides. In contrast, PcXyn11B showed limited activity towards acetyl xylan, but showed significantly increased activity after deacetylation of the xylan. Polysaccharide analysis using carbohydrate gel electrophoresis showed that PcXyn11B generated a broad range of products from native acetylated xylans extracted from birch wood and rice straw, including large residual xylooligosaccharides, while non-acetylated xylan from Japanese cedar was readily degraded into xylooligosaccharides. These results suggest that the degradability of native xylan by GH11 xylanases is highly dependent on the extent of acetyl group substitution. Analysis of 31 fungal genomes in the Carbohydrate-Active enZymes database indicated that the presence of GH11 xylanases is correlated to that of carbohydrate esterase (CE) family 1 acetyl xylan esterases (AXEs), while this is not the case for GH10 xylanases. These findings may imply co-evolution of GH11 xylanases and CE1 AXEs.     

Biodegradation of physicochemically treated LDPE by a consortium of filamentous fungi

Samples of low density polyethylene previously subjected to physicochemical treatments–thermal treatment (TT) at 105 and 150°C or accelerated aging treatment (AAT)–were subjected to biodegradation by a consortium of four fungi during 9 months. Morphological, structural, and surface changes and mineralization were evaluated. TT samples showed decreases in the onset melting temperature (T_o), melting point (T_m), relative crystallinity (Φ), and mean crystallite size (L₁₁₀). The degradation products in all treated samples were carbonyl and double bonds groups. The biological treatment (BT) affected the properties of all treated samples. T_o at 3 months decreased with respect to sample at 0 months; the changes were higher in TT samples; the samples then remained without significant changes. Increases in Φ were observed in TT samples within a 3‐month BT, after which reductions occurred. After a 9‐month BT, increases in L₁₁₀ were registered in all samples (up to 2.6 nm). The highest mineralization value (3.26%) was obtained with the AAT. The reported changes suggested that the fungi mainly digest the amorphous phase of polyethylene in the first stage of the experiment, but later they also digest small crystals. Superficial growth of microorganisms occurred, and penetration of hyphae was observed in most oxidized samples. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 265–271, 2004