木质素降解菌的筛选及其纤维素酶基因克隆表达研究

以高效降解木质素为指标, 进行木质素降解菌的筛选和纤维素酶处理纤维材料的研究.通过测定14株白腐菌菌株在愈创木酚、苯胺兰和鞣酸培养基上生长状况和酶活分泌能力, 得到8株能产生阳性反应的菌株.以木质素和综纤维素失重的比值(SF指数)为指标, 对这几株菌进行复筛, 从中筛选出具有生长优势和强酶分泌能力的菌株平菇10969和侧耳WP1.与黄胞原毛平革菌Phanerochaete chrysosporium RP78和P.chrysosporium BKM-F-1767两株模式菌相比, 白腐菌具有良好的生长优势、强酶系分泌能力和降解的优势.从分离的白腐菌中克隆纤维素酶基因(egl2), 表达蛋白并测定酶活.用粗酶液处理不同的纤维材料, 结果表明, 其还原糖产量为综纤维素(酸解)>菌草(白腐菌处理)>未处理菌草.白腐菌的研究对草质资源的充分利用、污染物的降解、燃料乙醇的开发以及我国生态农业的持续发展等都有着重要意义.     

不同参数超临界CO2处理对乳酸菌活性的影响

为了研究超临界CO₂作为非水相介质在生化反应工程中的作用，有必要考察超临界CO₂处理对微生物活性的影响。本文以乳酸杆菌为试验菌种，进行了该菌在不同参数超临界CO₂处理对菌体生长曲线、耐渗透压能力、耐酸能力、抑菌能力、降解胆固醇能力等活性指标影响的研究。结果表明：当提高超临界CO₂压强或延长超临界CO₂处理时间，乳酸杆菌的活性指标会发生如下变化：生长曲线的最大菌体浓度降低，但菌体的生长速率差异不大；菌体的耐渗透能力、耐酸能力降低；所得的抑菌圈比较明显，但抑菌圈直径减小；平均胆固醇降解率降低，而且长时间处理对降解效果的影响比高压强处理的明显。因此，在工程应用中需要研究一定的弥补措施。     

应用发光细菌监测重金属污染土壤和底泥的总体生物毒性

明亮发光杆菌T₃变种的生物毒性测定是一项新兴起的方法。该法依据有生物毒性的有机无机污染物对T₃菌荧光酶的敏感性,凭借在一定条件下,污染物浓度与T₃菌发光度呈线性负相关,从而可以快速、简便地测定污染环境的总体生物毒性。     

纤维素降解菌对农业有机废弃物发酵进行CO2施肥的作用

采用室内培养和大棚试验相结合,对分离的3种纤维素降解菌在有机废弃物发酵释放CO₂中的作用及其对增加大棚CO₂浓度的效果进行了研究。结果表明,分离获得的三种菌均能明显促进有机废弃物发酵CO₂的释放,其中菌A和菌C的效果优于菌B;3种菌混合接种时效果最佳。在大棚栽培条件下,昼间CO₂浓度大部分时间低于300μL/L,处于亏缺状态;采用棚中不接种直接发酵也可大幅提高大棚的CO₂浓度,但释放的时间只有9.d左右;采用3种菌混合接种的方法棚内全天维持CO₂浓度800μL/L以上的时间可达14.d以上。     

农药在土壤中降解反应的动力学模型

文章认为,农药在土壤中降解过程为化学降解反应与生物降解反应的平行总包反应,并推导其动力学方程:-(dx/dt)=k₁x+k₂xm; x=(A₁x₀)/[(A₁+A₂x₀)exp (A₁t)-A₂x₀]应用该方程对3种农药在土壤中降解过程的实验数据作回归拟合,全相关系数R值都达到0.001水平显著相关。由方程得出的降解反应动力学参数,都具有确切的物理涵义。预计此动力学模型对于其它类型农药在土壤中降解过程,有一定应用前景。     

TiO2纳米粒子气固相光催化降解乙烯初探

该文对TiO₂纳米粒子气固光催化降解果蔬贮藏环境乙烯技术进行了初步研究。采用溶胶-凝胶法制备的纳米TiO₂薄膜作光催化剂，利用自行设计的气固光催化实验系统，研究了乙烯浓度、紫外光作用时间对光催化降解反应的影响，探讨了乙烯的光催化降解的动力学。结果显示：该研究所制备的TiO₂锐钛矿型含量为48.766%，比表面积为47.186 m²/g，具有良好的光催化性能；光催化降解乙烯比直接紫外线光降解效果显著，光照10 min时光催化乙烯降解率比直接紫外线光降解提高23.76%；乙烯的降解率随着其浓度的增加而降低；乙烯的光催化降解的动力学可以用Langmuir-Hinshelwood动力学方程加以描述。     

不同气调包装方式的冷却猪肉在冷藏过程中的微生物变化

冷却猪肉分别采用真空包装、CO-MAP(CO+CO₂+N₂)包装、高氧-MAP(高浓度O₂+CO₂+N₂)和低氧-MAP(低浓度O₂+CO₂+N₂)包装后，在(4±1)℃贮存3周，每周测定各项微生物变化。结果表明：1)CO-MAP组可抑制腐败细菌的生长，除对乳酸菌抑制作用较弱外，对假单胞菌、肠杆菌科菌和热死环丝菌均具有很强的抑制作用     

嫩茎花椰菜在不同气调贮藏下叶绿素和维生素C的降解及活化能研究

通过检测叶绿素和维生素C的变化，试验确定了花椰菜气调贮藏中主要成份的降解为一级动力学反应；根据Arrhenius方程，确定了不同气调贮藏条件下花椰菜主要成份的表观活化能。在两种温度2℃和8℃，两种气体组分3% O₂，2% CO₂，95% N₂和6% O₂，6% CO₂，88% N₂组合条件下贮藏试验，结果表明在2℃，3% O₂，2% CO_{2相似文献}   

磷胁迫条件下油菜、肥田萝卜对难溶性磷的活化与利用

通过砂培试验研究了北方食用油菜和南方绿肥作物肥田萝卜两种植物在缺磷胁迫条件下对难溶性磷酸盐Ca₃(PO₄)₂和AlPO₄的活化利用情况。试验结果表明,在仅供应一种难浴性磷酸盐时,油菜和肥田萝卜对磷酸铝和磷酸三钙都有较大程度的活化与利用。在施用AlPO₄时肥田萝卜地上部吸磷量达到供应等磷量水溶性磷酸盐时的90％;在施用Ca₂(PO₄)₂时油菜地上部吸磷量达到供应等磷量水溶性磷酸盐时的49％。植物干物重的测定结果说明,在缺磷时,难溶性的Ca₃(PO₄)₂及AlPO₄对油菜和肥田萝卜均有促进生长的作用。但是,油菜与肥田萝卜对Ca₃(PO₄)₂和AlPO₄的活化利用程度却存在着一定差异。表现为油菜对Ca₃(PO₄)₂的利用能力强,而肥田萝卜对AlPO₄的利用能力强。     

高产漆酶平菇的筛选及其在降解黄曲霉毒素B1中的应用

通过选择培养基平板培养法和液体发酵培养法筛选得到2株高产漆酶的平菇菌株P1和P2,并对平菇菌株产漆酶的培养基进行筛选,得到产漆酶的最适培养基为最低盐MSM培养基。菌株P1不仅产漆酶能力最高,而且降解黄曲霉毒素的能力也最好。在MSM培养基中培养10d时,产漆酶量高达769.44U/L,在800μl的反应体系中,790μl粗酶液可以将1000ng黄曲霉毒素B₁降解到222.62ng,降解率为77.74%,并且平菇粗酶液降解黄曲霉毒素B₁的能力与其中漆酶的含量呈一定的正相关性。     

Effect of environmental C/N ratio on activities of lignin-degrading enzymes produced by Phanerochaete chrysosporium

Lignin-degrading enzymes secreted by white rot fungi play an important role in the degradation of lignin and persistent organic pollutants(POPs).In this study,effect of environmental C/N ratio on the activities of lignin-degrading enzymes,lignin peroxide(Li P)and manganese peroxidase(Mn P),produced by Phanerochaete chrysosporium,a white rot fungus,was investigated.Glucose was used as C source,and ammonium tartrate of different concentrations was used as N source to provide different C/N ratios.Relationships between Li P and Mn P activities and environmental C/N ratio were explored.The results showed that the higher the N source concentration,the faster the mycelium pellets aged.The faster the mycelium dry weight increased,the higher the Li P and Mn P activities.A high C/N ratio was a necessary condition for the secretion of Li P or Mn P.In addition,mycelium dry weight essentially affected enzyme activities.In the 122 C/N ratio and 50 C/N ratio treatments,mycelium dry weight essentially affected Mn P activity and both Li P and Mn P activities,respectively.     

Co-remediation of DDT-contaminated soil using white rot fungi and laccase extract from white rot fungi

Purpose

2,2-Bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT), one of the most widely used organochlorine pesticides in soil, was banned in the 1970s for agricultural use because of its detrimental impacts on wildlife and harmful effects on human health via the food chain. However, high levels of DDT are frequently detected in agricultural soils in China. Considering this situation, this study investigated the use of white rot fungi and laccase derived from white rot fungi to co-remediate DDT-contaminated soil.

Materials and methods

A culture of white rot fungi was used to inoculate soil samples and also to extract laccase from. Soil was contaminated with four components of DDT (p,p′-DDE, o,p′-DDT, p,p′-DDD, and p,p′-DDT). Individual DDT components and the sum of the DDT components (p,p′-DDE, o,p′-DDT, p,p′-DDD, and p,p′-DDT—collectively referred to as DDTs) were both analyzed by GC at various stages during the incubation period. The efficacy of co-remediating DDT-contaminated soil using white rot fungi and laccase was tested by investigating how degradation varied with varying amounts of white rot fungi, sterilizing soil, temperature, soil pH, concentrations of DDT, and concentration of the heavy metal ion Cd²⁺.

Results and discussion

“”It was concluded that the reduction of DDTs in soil using white rot fungi and laccase was higher than reduction using only white rot fungi or laccase by nearly 14 and 16 %, respectively. Five milliliters fungi per 15 g soil and 6 U laccase per gram soil were the optimal application rates for remediation, as shown by a reduction in DDTs of 66.82 %. The difference in the reduction of individual DDT components and DDTs between natural and sterilized soils was insignificant. The optimal temperature and pH in the study were 28 °C and 4.5, respectively. In addition, reduction of individual DDT components and DDTs increased with increasing concentrations of DDT and decreased with increasing concentrations of Cd²⁺.

Conclusions

Compared with the remediation of DDT using only white rot fungi or laccase, the co-remediation of DDT using white rot fungi and laccase degraded DDT in soil more rapidly and efficiently; the highest reduction of DDTs was 66.82 %.     

Degradation of phenolic and non-phenolic aromatic pollutants by four Pleurotus species: the role of laccase and versatile peroxidase

The ability of Pleurotus eryngii, Pleurotus ostreatus, Pleurotus pulmonarius and Pleurotus sajor-caju to degrade the aromatic pollutants 2,4-dichorophenol (2,4-DCP) and benzo(a)pyrene [B(a)P] in liquid culture and microcosm (using wheat straw as growth substrate and sea sand as a xenobiotic carrier) was investigated by HPLC and ¹⁴CO₂ release from labeled pollutants. We found that 100 μM 2,4-DCP was very quickly transformed by the four fungi, disappearing 24 h after its addition to the liquid cultures. However, a 2-week incubation period was required to transform 100 μM B(a)P up to 75% by P. eryngii and P. pulmonarius. Whereas the fungi were able to begin degradation of the two pollutants with high transformation rates, their complete degradation (mineralization) rates were very low. Mineralization of B(a)P in liquid cultures was only observed with P. eryngii and P. pulmonarius, although the four Pleurotus species studied were able to mineralize this compound in solid state fermentation (SSF). The ligninolytic enzymes laccase and versatile peroxidase (VP), together with aryl-alcohol oxidase (AAO) providing extracellular H₂O₂, were found in liquid cultures. Except AAO, these enzymes were also detected in SSF experiments. In order to investigate the role of ligninolytic enzymes in the process, their action on both pollutants (50 μM) was studied in vitro in the absence and presence of redox mediators. As observed with the fungal cultures, 2,4-DCP was oxidized faster than B(a)P by both laccase (60% transformation after 6 h) and VP (100% transformation after 1 h). Moreover, laccase oxidation was strongly increased (up to 90% transformation after 3 h), by the presence of the mediators 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) or 1-hydroxybenzotriazole (HBT). In the case of B(a)P, the presence of ABTS or HBT was strictly required for oxidation by laccase (25% transformation after 8 h). Degradation of B(a)P was also observed in reactions with VP (40% transformation after 6 h). The results obtained suggest that Pleurotus species can be used in applications focused to the degradation of aromatic pollutants using wheat straw as a growth substrate, and provide the first evidence on the direct transformation of recalcitrant aromatic pollutants by VP.     

The Production of Ligninolytic Enzymes by Marine-Derived Basidiomycetes and Their Biotechnological Potential in the Biodegradation of Recalcitrant Pollutants and the Treatment of Textile Effluents

Filamentous fungi derived from marine environments are well known as a potential genetic resource for various biotechnological applications. Although terrestrial fungi have been reported to be highly efficient in the remediation of xenobiotic pollutants, fungi isolated from the marine environment may possess biological advantages over terrestrial fungi because of their adaptations to high salinity and pH extremes. The present study describes the production of ligninolytic enzymes under saline and non-saline conditions and the decolorization of Remazol Brilliant Blue R (RBBR) dye by three basidiomycetes recovered from marine sponges (Tinctoporellus sp. CBMAI 1061, Marasmiellus sp. CBMAI 1062, and Peniophora sp. CBMAI 1063). Ligninolytic enzymes were primarily produced by these fungi in a salt-free malt extract and malt extract formulated with artificial seawater (saline condition). CuSO₄ and wheat bran were the best inducers of lignin peroxidase and manganese peroxidase activity. RBBR was decolorized up to 100% by the three fungi, and Tinctoporellus sp. CBMAI 1061 was the most efficient. Our results revealed the biotechnological potential of marine-derived basidiomycetes for dye decolorization and the treatment of colored effluent as well as for the degradation of other organopollutants by ligninolytic enzymes in non-saline and saline conditions that resemble the marine environment.     

Decomposition of lignin in wheat straw in a sand-dune grassland

The degradation of organic macromolecules, including lignin, in plant-derived soil organic matter, is important to the global carbon cycle. In grasslands, saprotrophic (decomposer) fungi are major decomposers of such organic material. The aim of this study was to characterise lignin degradation, particularly with respect to lignin oxidation typical of white-rot basidiomycete fungi. Lignin breakdown products, analysed by gas chromatography–mass spectrometry (GC–MS) with TMAH thermochemolysis, in initial wheat (Triticum aestivum var. Swatham) straw samples were compared with those in samples which had been buried as a “model” resource for 46 months in a sand-dune grassland at Ainsdale National Nature Reserve, Lancashire, UK.Our results showed that lignin oxidation occurred in the straw over the 46 month period, as there were general increases in the [Ac/Al]_S and [Ac/Al]_G ratios and a clear decrease in the [S/G] ratio. These data provide tentative support for the theory that white-rot basidiomycete fungi are involved in the degradation of lignin in grasslands.     

A Stable Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>/Expanded Perlite Composite Catalyst for Degradation of Rhodamine B in Heterogeneous Photo-Fenton System

A stable and efficient Fe₂O₃/expanded perlite (Fe₂O₃-Ep) composite catalyst was synthesized by a simple hydrothermal method for degradation of refractory contaminants in heterogeneous photo-Fenton system. X-ray diffraction and FT-IR analyses confirmed the presence of the Fe₂O₃ in the synthesized catalyst. The catalytic activity of the Fe₂O₃-Ep catalyst was evaluated by the degradation of rhodamine B (RhB, 5 mg/L) and metronidazole (MET, 5 mg/L) in the presence of H₂O₂ under visible light irradiation. The Fe₂O₃-Ep catalyst exhibited high efficiency for degradation of RhB at a wide pH range from 2 to 10 and showed excellent catalytic property for decomposition of MET as well. The degradation ratio of RhB was achieved 99%, and the removal ratio of COD was 62% within 90 min at the best experimental conditions (0.5 g/L of Fe₂O₃-Ep catalyst, 2 mL/L of H₂O₂). Furthermore, iron leaching of the Fe₂O₃-Ep catalyst during the catalytic degradation reaction was negligible and the catalyst still exhibited high catalytic activity and stability after five cycles. These results show that the catalyst can be used as a highly efficient heterogeneous photo-Fenton catalyst for the degradation of non-biodegradable refractory pollutants in water.     

Microbial community response to nitrogen deposition in northern forest ecosystems

The productivity of temperate forests is often limited by soil N availability, suggesting that elevated atmospheric N deposition could increase ecosystem C storage. However, the magnitude of this increase is dependent on rates of soil organic matter formation as well as rates of plant production. Nonetheless, we have a limited understanding of the potential for atmospheric N deposition to alter microbial activity in soil, and hence rates of soil organic matter formation. Because high levels of inorganic N suppress lignin oxidation by white rot basidiomycetes and generally enhance cellulose hydrolysis, we hypothesized that atmospheric N deposition would alter microbial decomposition in a manner that was consistent with changes in enzyme activity and shift decomposition from fungi to less efficient bacteria. To test our idea, we experimentally manipulated atmospheric N deposition (0, 30 and 80 kg NO₃⁻-N) in three northern temperate forests (black oak/white oak (BOWO), sugar maple/red oak (SMRO), and sugar maple/basswood (SMBW)). After one year, we measured the activity of ligninolytic and cellulolytic soil enzymes, and traced the fate of lignin and cellulose breakdown products (¹³C-vanillin, catechol and cellobiose).In the BOWO ecosystem, the highest level of N deposition tended to reduce phenol oxidase activity (131±13 versus 104±5 μmol h⁻¹ g⁻¹) and peroxidase activity (210±26 versus 190±21 μmol h⁻¹ g⁻¹) and it reduced ¹³C-vanillin and ¹³C-catechol degradation and the incorporation of ¹³C into fungal phospholipids (p<0.05). Conversely, in the SMRO and SMBW ecosystems, N deposition tended to increase phenol oxidase and peroxidase activities and increased vanillin and catechol degradation and the incorporation of isotope into fungal phospholipids (p<0.05). We observed no effect of experimental N deposition on the degradation of ¹³C-cellulose, although cellulase activity showed a small and marginally significant increase (p<0.10). The ecosystem-specific response of microbial activity and soil C cycling to experimental N addition indicates that accurate prediction of soil C storage requires a better understanding of the physiological response of microbial communities to atmospheric N deposition.     

Breakdown Products in the Metabolic Pathway of Anthracene Degradation by a Ligninolytic Fungus Polyporus sp. S133

Polyporus sp. S133 fungi were selected based on their ability to degrade anthracene in liquid media. The degradation efficiency of anthracene increased by adding 0.5% Tween 80 to reach 71%; agitation at 120 rev/min increased the degradation to 92% after 30?days of incubation. Enzymes such as manganese peroxidase (MnP), lignin peroxidase (LiP), laccase, 1,2-dioxygenase and 2,3-dioxgenase were produced by Polyporus sp. S133 during incubation, and the highest enzyme activity was 182.3 U l^?1 by 1,2-dioxygenase after 20?days of incubation. These results indicate that ligninolytic and dioxygenase enzymes secreted from Polyporus sp. S133 could play an important role in anthracene degradation efficiency. The metabolites detected through the degradation pathway were anthraquinone, phthalic acid, benzoic acid and catechol.     

Functional guild classification predicts the enzymatic role of fungi in litter and soil biogeochemistry

Linking community composition to ecosystem function is a challenge in complex microbial communities. We tested the hypothesis that key biological features of fungi - evolutionary history, functional guild, and abundance of functional genes – can predict the biogeochemical activity of fungal species during decay. We measured the activity of 10 different enzymes produced by 48 model fungal species on leaf litter in laboratory microcosms. Taxa included closely related species with different ecologies (i.e. species in different “functional guilds”) and species with publicly available genomes. Decomposition capabilities differed less among phylogenetic lineages of fungi than among different functional guilds. Activity of carbohydrases and acid phosphatase was significantly higher in litter colonized by saprotrophs compared to ectomycorrhizal species. By contrast, oxidoreductase activities per unit fungal biomass were statistically similar across functional guilds, with white rot fungi having highest polyphenol oxidase activity and ectomycorrhizal fungi having highest peroxidase activity. On the ecosystem level, polyphenol oxidase activity in soil correlated with the abundance of white rot fungi, while soil peroxidase activity correlated with the abundance of ectomycorrhizal fungi in soil. Copy numbers of genes coding for different enzymes explained the activity of some carbohydrases and polyphenol oxidase produced by fungi in culture, but were not significantly better predictors of activity than specific functional guild. Collectively, our data suggest that quantifying the specific functional guilds of fungi in soil, potentially through environmental sequencing approaches, allows us to predict activity of enzymes that drive soil biogeochemical cycles.