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1.
The effect of Fe3(+) treatment on weak cation exchange column chromatography was demonstrated for monoclonal antibody (MAb) analysis. Fe3(+)-exposed columns showed lowered relative peak areas of the parent MAb peak as well as both acidic and basic variant peaks that could lead to erroneous conclusions. Accurate measurement of relative amounts of variants to the parent MAb is essential for demonstrating the safety and efficacy of therapeutic molecules such as MAbs. Complete reversal of the compromised MAb analysis performance was observed after washing the column with chelating agents, confirming that metal contamination was responsible for the compromised column performance. 相似文献
2.
Maria Augusta HortaFernando Masarin Jaime RodriguezAndré Ferraz 《International biodeterioration & biodegradation》2011,65(1):164-171
This work evaluates linoleic acid peroxidation reactions initiated by Fe3+-reducing compounds recovered from Eucalyptus grandis, biotreated with the biopulping fungus Ceriporiopsis subvermispora. The aqueous extracts from biotreated wood had the ability to reduce Fe3+ ions from freshly prepared solutions. The compounds responsible for the Fe3+-reducing activity corresponded to UV-absorbing substances with apparent molar masses from 3 kDa to 5 kDa. Linoleic acid peroxidation reactions conducted in the presence of Fe3+ ions and the Fe3+-reducing compounds showed that the rate of O2 consumption during peroxidation was proportional to the Fe3+-reducing activity present in each extract obtained from biotreated wood. This peroxidation reaction was coupled with in-vitro treatment of ball-milled E. grandis wood. Ultraviolet data showed that the reaction system released lignin fragments from the milled wood. Size exclusion chromatography data indicated that the solubilized material contained a minor fraction representing high-molar-mass molecules excluded by the column and a main low-molar-mass peak. Overall evaluation of the data suggested that the Fe3+-reducing compounds formed during wood biodegradation by C. subvermispora can mediate lignin degradation through linoleic acid peroxidation. 相似文献
3.
4.
Ozkaya B Sahinkaya E Nurmi P Kaksonen AH Puhakka JA 《Bioprocess and biosystems engineering》2008,31(2):111-117
The performance of a biological Fe2+ oxidizing fluidized bed reactor (FBR) was modeled by a popular neural network-back-propagation algorithm over a period of
220 days at 37 °C under different operational conditions. A method is proposed for modeling Fe3+ production in FBR and thereby managing the regeneration of Fe3+ for heap leaching application, based on an artificial neural network-back-propagation algorithm. Depending on output value,
relevant control strategies and actions are activated, and Fe3+ production in FBR was considered as a critical output parameter. The modeling of effluent Fe3+ concentration was very successful, and an excellent match was obtained between the measured and the predicted concentrations. 相似文献
5.
The toxic effect of the Fe2+ and Fe3+ ions on the luminescent recombinant Escherichia coli strain with the luxCDABE operon was studied in short- and long-term experiments. At 30-min exposure of bacteria to the iron ions, the effective concentrations of Fe2+ and Fe3+ resulting in acute toxicity (EC50) were 8.5 and 1.3 mg/L, respectively. In the long-term (24 h) experiment, during active bacterial growth, the toxicity index for Fe2+ and Fe3+ was 65.5 and 62.8, respectively. Addition of the iron ions into the medium did not suppress growth, although it inhibited luminescence. Comparative analysis of the short- and long-term experiments made it possible to assess iron toxicity at the concentrations from 0.5 to 20 mg/L (as calculated for the Fe2+ and Fe3+ ions). Iron ions were found to affect only the reactions that were not vitally important for the cell. At the same time, they had no negative effect on the genetic mechanisms and protein synthesis, thus indicating non-specific toxicity of Fe2+ and Fe3+. 相似文献
6.
M J MacDonald 《Biochemical and biophysical research communications》1979,90(3):741-749
3-Mercaptopicolinic acid is known to be an inhibitor of phosphoenolpyruvate carboxykinase and 3-aminopicolinic acid permits Fe2+ to activate the enzyme. The potency of mercaptopicolinate is increased by incubating the enzyme with Fe2+ prior to assaying for activity. In the present work, the average combining ratio of either pyridine carboxylate with Fe2+ at pH 7.5 was determined to be 2:1 when measured by the method of continuous variation of Job or by elemental analysis of the isolated pyridine carboxylate-Fe2+ complexes. The ratio of 3-mercaptopicolinate or 3-aminopicolinate to Fe2+ that caused the greatest inhibition or activation of purified phosphoenolpyruvate carboxykinase was 2:1. In the absence of Fe2+, neither pyridine carboxylate altered the activity of the enzyme. These results indicate that the two pyridine carboxylates can interact with phosphoenolpyruvate carboxykinase as Fe2+ coordination complexes. 相似文献
7.
Matthew Kennedy Lian Yu Maria João Lima Carla S. Ascenso Christopher Czaja Isabel Moura Jose J. G. Moura F. Rusnak 《Journal of biological inorganic chemistry》1998,3(6):643-649
Desulforedoxin and the N-terminus of desulfoferrodoxin share a 36 amino acid domain containing a (Cys-S)4 metal binding site. Recombinant forms of desulforedoxin, an N-terminal fragment of desulfoferrodoxin, and two desulforedoxin
mutant proteins were reconstituted with Fe3+, Cd2+, and Zn2+ and relative metal ion affinities assessed by proton titrations. Protons compete with metal for protein ligands, a process
that can be followed by monitoring the optical spectrum of the metal-protein complex as a function of pH. For all polypeptides,
Fe3+ bound with the highest affinity, whereas the affinity of Zn2+ was greater than Cd2+ in desulforedoxin and the N-terminal fragment of desulfoferrodoxin, but this order was reversed in desulforedoxin mutant
proteins. Metal binding in both mutants was significantly impaired. Furthermore, the Fe3+ complex of both mutants underwent a time-dependent bleaching process which coincided with increased reactivity of cysteine
residues to Ellman's reagent and concomitant metal dissociation. It is hypothesized that this results from an autoredox reaction
in which Fe3+ is reduced to Fe2+ with attendant oxidation of ligand thiols.
Received: 17 June 1998 / Accepted: 3 September 1998 相似文献
8.
《Biochimica et Biophysica Acta (BBA)/General Subjects》2002,1571(1):45-54
Formation of 7,8-dihydro-8-oxo-2′-deoxyguanosine (8-oxo-dG) in solutions of free 2′-deoxyguanosine (dG) and calf thymus DNA (DNA) was compared for the diffusion-dependent and localised production of oxygen radicals from phosphate-mediated oxidation of ferrous iron (Fe2+) to ferric iron (Fe3+). The oxidation of Fe2+ to Fe3+ was followed at 304 nm at pH 7.2 under aerobic conditions. Given that the concentration of Fe2+ ≥phosphate concentration, the rate of Fe2+ oxidation was significantly higher in DNA-phosphate as compared for the same concentration of inorganic phosphate. Phosphate catalysed oxidation of ferrous ions in solutions of dG or DNA led through the production of reactive oxygen species to the formation of 8-oxo-dG. The yield of 8-oxo-dG in solutions of dG or DNA correlated positively with the inorganic-/DNA-phosphate concentrations as well as with the concentrations of ferrous ions added. The yield of 8-oxo-dG per unit oxidised Fe2+ were similar for dG and DNA; thus, it differed markedly from radiation-induced 8-oxo-dG, where the yield in DNA was several fold higher.For DNA in solution, the localisation of the phosphate ferrous iron complex relative to the target is an important factor for the yield of 8-oxo-dG. This was supported from the observation that the yield of 8-oxo-dG in solutions of dG was significantly increased over that in DNA only when Fe2+ was oxidised in a high excess of inorganic phosphate (50 mM) and from the lower protection of DNA damage by the radical scavenger (hydroxymethyl)aminomethane (Tris)–HCl. 相似文献
9.
Ashraf F. Elbaz Ahmed Sobhi Ahmed ElMekawy 《Bioprocess and biosystems engineering》2015,38(4):767-776
The discovery of novel bacterial cyclodextrin glucanotransferase (CGTase) enzyme could provide advantages in terms of its production and relative activity. In this study, eight bacterial strains isolated from soils of a biodiversity-rich vegetation in Egypt based on their hydrolyzing activity of starch, were screened for CGTase activity, where the most active strain was identified as Bacillus lehensis. Optimization process revealed that the using of rice starch (25 %) and a mixture of peptone/yeast extract (1 %) at pH 10.5 and 37 °C for 24 h improved the bacterial growth and enzyme activity. The bacterial CGTase was successively purified by acetone precipitation, gel filtration chromatography in a Sephadex G-100 column and ion exchange chromatography in a DEAE-cellulose column. The specific activity of the CGTase was increased approximately 274-fold, from 0.21 U/mg protein in crude broth to 57.7 U/mg protein after applying the DEAE-cellulose column chromatography. SDS-PAGE showed that the purified CGTase was homogeneous with a molecular weight of 74.1 kDa. Characterization of the enzyme exhibited optimum pH and temperature of 7 and 60 °C, respectively. CGTase relative activity was strongly inhibited by Mg2+, Zn2+, Al3+ and K+, while it was slightly enhanced by 5 and 9 % with Cu2+ and Fe2+ metal ions, respectively. 相似文献
10.
Yong Ran Shaoyu Wang Qianye Yin Aoli Wen Xiaoxiao Peng Yunfei Long Shu Chen 《Luminescence》2020,35(6):870-876
Water‐soluble carbon dots (CDs) were synthesized using a one‐step hydrothermal treatment of chloroplast dispersions extracted from fresh leaves as a green carbon source. The CD solution showed an emission peak centred at 445 nm when excited at 300 nm. The synthesized CDs were uniform and monodispersed with an average size of 5.6 nm. When adding ferric(III) ions (Fe3+) to the solution of the original CDs, the fluorescence intensity decreased significantly. Based on the linear relationship between fluorescence intensity and concentration of Fe3+ ions, an effective method for rapid, sensitive and selective Fe3+ sensing in aqueous solution could be established. Under optimum conditions, the extent of the fluorescence quenching of prepared CDs strongly depended on the Fe3+ ions over a wide concentration range 1.0–100.0 μM with a detection limit (3σ/k) of 0.3 μM. Furthermore, the quantitative determination of Fe3+ ions in environmental water samples was realized. 相似文献
11.
To increase the antimicrobial activities of chitosan, chitosan nanoparticles loaded with Fe2+ or Fe3+ were prepared by surfactant‐assisted chitosan chelating Fe2+, Fe3+ and ionic gelation chitosan. Their chelating rates were determined by spectrophotometry. The particle sizes and zeta potentials of chitosan nanoparticles loaded with Fe2+ or Fe3+ were measured by size and zeta potential analysis. The nanoparticles antimicrobial activities were evaluated by different concentration against Escherichia coli, Staphylococcus aureus, Candida albicans in vitro. Results showed that the mean diameter of chitosan nanoparticles loaded with Fe2+ or Fe3+ were 206.4 and 195.2 nm, respectively. Their zeta potentials were +28.82 and +28.26 mV, respectively. The chelating rate of chitosan nanoparticles loaded with Fe2+ was greatly higher than with Fe3+. Their antimicrobial activity was showed greatly higher at lower concentrations compared to chitosan, and the antibacterial effect of chitosan nanoparticles loaded with Fe2+ or Fe3+ was preliminary observed. 相似文献
12.
铁是好氧微生物生长所必需的元素,而铁污染土壤环境中的根瘤菌是否对高浓度铁具有耐受性和钝化能力尚不清楚。以攀枝花钒钛磁铁尾矿土壤作为基质进行水黄皮共生根瘤菌捕获实验,获得水黄皮共生根瘤并从中分离纯化出根瘤菌39株。通过Fe~(2+)/Fe~(3+)耐受性和钝化能力测试筛选出耐受性和钝化能力均强的优势菌株PZHS20、PZHS90、PZHS87,其对Fe~(2+)的最大耐受质量浓度为1 600 mg/L,其中PZHS20在200 mg/L Fe~(2+)溶液中钝化效率最大,为73.54%;PZHS90对Fe~(3+)的最大耐受质量浓度为1 600 mg/L,而PZHS20和PZHS87对Fe~(3+)的最大耐受质量浓度为1 800 mg/L,其在200 mg/L Fe~(3+)溶液中钝化效率分别为84.25%和81.95%。16S rRNA基因系统进化分析将PZHS20鉴定为苍白杆菌(Ochrobactrum),将PZHS90和PZHS87鉴定为慢生根瘤菌(Bradyrhizobium)。研究结果表明,钒钛磁铁尾矿土壤中的水黄皮根瘤菌具有不同程度的Fe~(2+)/Fe~(3+)耐受性和钝化能力,筛选出的优势菌株为进一步利用水黄皮-根瘤菌联合修复高浓度铁污染土壤提供可利用的菌株资源。 相似文献
13.
Anatoly F. Vanin Xiaoping Liu Alexandre Samouilov Reonald A. Stukan Jay L. Zweier 《Biochimica et Biophysica Acta (BBA)/General Subjects》2000,1474(3):365-377
While the Fe2+–dithiocarbamate complexes have been commonly used as NO traps to estimate NO production in biological systems, these complexes can undergo complex redox chemistry. Characterization of this redox chemistry is of critical importance for the use of this method as a quantitative assay of NO generation. We observe that the commonly used Fe2+ complexes of N-methyl-D-glucamine dithiocarbamate (MGD) or diethyldithiocarbamate (DETC) are rapidly oxidized under aerobic conditions to form Fe3+ complexes. Following exposure to NO, diamagnetic NO–Fe3+ complexes are formed as demonstrated by the optical, electron paramagnetic resonance and gamma-resonance spectroscopy, chemiluminescence and electrochemical methods. Under anaerobic conditions the aqueous NO–Fe3+–MGD and lipid soluble NO–Fe2+–DETC complexes gradually self transform by reductive nitrosylation into paramagnetic NO–Fe2+–MGD complexes with yield of up to 50% and the balance is converted to Fe3+–MGD and nitrite. In dimethylsulfoxide this process is greatly accelerated. More efficient transformation of NO–Fe3+–MGD into NO–Fe2+–MGD (60–90% levels) was observed after addition of reducing equivalents such as ascorbate, hydroquinone or cysteine or with addition of excess Fe2+–MGD. With isotope labeling of the NO–Fe3+–MGD with 57Fe, it was shown that these complexes donate NO to Fe2+–MGD. NO–Fe3+–MGD complexes were also formed by reversible oxidation of NO–Fe2+–MGD in air. The stability of NO–Fe3+–MGD and NO–Fe2+–MGD complexes increased with increasing the ratio of MGD to Fe. Thus, the iron–dithiocarbamate complexes and their NO derivatives exhibit complex redox chemistry that should be considered in their application for detection of NO in biological systems. 相似文献
14.
Copper toxicity has been studied in three nickel-resistant strains ofNeurospora crassa (NiR1, NiR2, and NiR3). NiR1 and NiR2, but not NiR3, were two-to threefold more sensitive than the parent wild strain (N. crassa EM 5297a) to Cu2+ on a normal N medium. On a nitrate N medium, Cu2+ was 16-fold more toxic to NiR3 because of reduced synthesis of nitrite reductase; NiR1 and NiR2 were only fivefold more sensitive to Cu2+, and nitrite reductase synthesis was unaffected. Mn2+ reversed Cu2+ toxicity on normal N medium only, in all strains. Fe3+ counteracted Cu2+ toxicity on nitrate N medium also. It was shown that Cu2+ affected Fe3+ utilization for nitrite reductase synthesis in NiR3 only and that in these Ni2+-resistant strains, Fe3+ antagonized effects of Cu2+, but not of other toxic metal ions. 相似文献
15.
P. Nurmi B.
zkaya A.H. Kaksonen O.H. Tuovinen M.-L. Riekkola-Vanhanen J.A. Puhakka 《Process Biochemistry》2009,44(12):1315-1322
Iron has a central role in bioleaching and biooxidation processes. Fe2+ produced in the dissolution of sulfidic minerals is re-oxidized to Fe3+ mostly by biological action in acid bioleaching processes. To control the concentration of iron in solution, it is important to precipitate the excess as part of the process circuit. In this study, a bioprocess was developed based on a fluidized-bed reactor (FBR) for Fe2+ oxidation coupled with a gravity settler for precipitative removal of ferric iron. Biological iron oxidation and partial removal of iron by precipitation from a barren heap leaching solution was optimized in relation to the performance and retention time (τFBR) of the FBR. The biofilm in the FBR was dominated by Leptospirillum ferriphilum and “Ferromicrobium acidiphilum.” The FBR was operated at pH 2.0 ± 0.2 and at 37 °C. The feed was a barren leach solution following metal recovery, with all iron in the ferrous form. 98–99% of the Fe2+ in the barren heap leaching solution was oxidized in the FBR at loading rates below 10 g Fe2+/L h (τFBR of 1 h). The optimal performance with the oxidation rate of 8.2 g Fe2+/L h was achieved at τFBR of 1 h. Below the τFBR of 1 h the oxygen mass transfer from air to liquid limited the iron oxidation rate. The precipitation of ferric iron ranged from 5% to 40%. The concurrent Fe2+ oxidation and partial precipitative iron removal was maximized at τFBR of 1.5 h, with Fe2+ oxidation rate of 5.1 g Fe2+/L h and Fe3+ precipitation rate of 25 mg Fe3+/L h, which corresponded to 37% iron removal. The precipitates had good settling properties as indicated by the sludge volume indices of 3–15 mL/g but this step needs additional characterization of the properties of the solids and optimization to maximize the precipitation and to manage sludge disposal. 相似文献
16.
Henrique de Santana Andrea Paesano Jr. Antonio C. S. da Costa Eduardo di Mauro Ivan G. de Souza Flávio F. Ivashita Cláudio M. D. de Souza Cássia T. B. V. Zaia Dimas A. M. Zaia 《Amino acids》2010,38(4):1089-1099
The present study examined the adsorption of cysteine, thiourea and thiocyanate on bentonite and montmorillonite at two different pHs (3.00, 8.00). The conditions used here are closer to those of prebiotic earth. As shown by FT-IR, Mössbauer and EPR spectroscopy and X-ray diffractometry, the most important finding of this work is that cysteine and thiourea penetrate into the interlayer of the clays and reduce Fe3+ to Fe2+, and as consequence, cystine and c,c′-dithiodiformamidinium ion are formed. This mechanism resembles that which occurs with aconitase. This is a very important result for prebiotic chemistry; we should think about clays not just sink of molecules, but as primitive vessels of production of biomolecules. At pH 8.00, an increasing expansion was observed in the following order for both minerals: thiourea > thiocyanate > cysteine. At pH 3.00, the same order was not observed and thiourea had an opposite behavior, being the compound producing the lowest expansion. Mössbauer spectroscopy showed that at pH 8.00, the proportion of Fe2+ ions in bentonite increased, doubling for thiourea, or more than doubling for cysteine, in both clays. However, at pH 3.00, cysteine and thiourea did not change significantly the relative amount of Fe2+ and Fe3+ ions, when compared to clays without adsorption. For thiocyanate, the amount of Fe2+ produced was independent of the pH or clay used, probably because the interlayers of clays are very acidic and HSCN formed does not reduce Fe3+ to Fe2+. For the interaction of thiocyanate with the clays, it was not possible to identify any potential compound formed. For the samples of bentonite and montmorillonite at pH 8.00 with cysteine, EPR spectroscopy showed that intensity of the lines due to Fe3+ decreased because the reaction of Fe3+/cysteine. Intensity of EPR lines did not change when the samples of bentonite at pH 3.00 with and without cysteine were compared. These results are in accordance with those obtained using Mössbauer and FT-IR spectroscopy. 相似文献
17.
Jian Qu Qiaoling Hu Kai Shen Ke Zhang Youliang Li Hao Li Qirong Zhang Jieqiong Wang Wenqi Quan 《Carbohydrate research》2011,(6):822
Chitosan composite rods (CS–Fe3+) were prepared via an in situ precipitation method. The relationships among the preparation, structures, and properties of the CS–Fe3+ composite rods have been investigated. The results of Fourier-transform infrared spectroscopy (FTIR) and core electron X-ray photoelectron spectroscopy (XPS) indicate that the CS and Fe3+ are coordinated via a chelation mechanism. The content of Fe3+ in the complex was determined by atomic absorption spectrometry (AAS) and elemental analysis (EA), the results of which suggested that the content of Fe3+ in the complex can be controlled by the concentration of the ferric salts during coordination. The changes in thermal stability and crystallization properties were measured by thermogravimetric analysis (TGA) and X-ray diffraction (XRD) patterns, respectively. Scanning electron microscopy (SEM) was used to observe the morphological change of the CS–Fe3+ complex rod. After coordination with Fe3+, the CS rod had a denser, layered structure. However, the layered structure cannot remain intact when the ratios of –NH2/Fe3+ are 100/15 and 100/20. Moreover, its thermal stability decreased, and its bending strength was improved significantly (from 86 MPa to more than 210 MPa), despite the remarkable decrease in the degree of crystallinity. 相似文献
18.
Elisabeth M. Froschauer Rudolf J. Schweyen Gerlinde Wiesenberger 《生物化学与生物物理学报:生物膜》2009,1788(5):1044-1050
The yeast proteins Mrs3p and Mrs4p are two closely related members of the mitochondrial carrier family (MCF), which had previously been implicated in mitochondrial Fe2+ homeostasis. A vertebrate Mrs3/4 homologue named mitoferrin was shown to be essential for erythroid iron utilization and proposed to function as an essential mitochondrial iron importer. Indirect reporter assays in isolated yeast mitochondria indicated that the Mrs3/4 proteins are involved in mitochondrial Fe2+ utilization or transport under iron-limiting conditions. To have a more direct test for Mrs3/4p mediated iron uptake into mitochondria we studied iron (II) transport across yeast inner mitochondrial membrane vesicles (SMPs) using the iron-sensitive fluorophore PhenGreen SK (PGSK). Wild-type SMPs showed rapid uptake of Fe2+ which was driven by the external Fe2+ concentration and stimulated by acidic pH. SMPs from the double deletion strain mrs3/4Δ failed to show this rapid Fe2+ uptake, while SMPs from cells overproducing Mrs3/4p exhibited increased Fe2+ uptake rates. Cu2+ was transported at similar rates as Fe2+, while other divalent cations, such as Zn2+ and Cd2+ apparently did not serve as substrates for the Mrs3/4p transporters. We conclude that the carrier proteins Mrs3p and Mrs4p transport Fe2+ across the inner mitochondrial membrane. Their activity is dependent on the pH gradient and it is stimulated by iron shortage. 相似文献
19.
Two light sources differentially affected ferric iron reduction and growth of cotton 总被引:1,自引:0,他引:1
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In growth chambers, low pressure sodium (LPS) plus incandescent (Inc) lamps and fluorescent cool-white (FCW) plus Inc lamps were used to determine their effects on growth of cotton (Gossypium hirsutum L.) and on the reduction of Fe3+ to Fe2+. Cotton plants grown under LPS + Inc light developed chlorosis and grew poorly, whereas plants grown under FCW + Inc lights were green. The chlorophyll concentration and top and root weights of cotton grown under LPS + Inc were lower than those under FCW + Inc. In solution, FCW + Inc lamps reduced about eight times more Fe3+ to Fe2+ than did LPS + Inc lamps. Fe3+ is transported to plant tops as Fe3+ citrate and if we assume that FCW + Inc light reduces Fe3+ to Fe2+ in plant foliage as it did in the solutions, then reduction of Fe3+ by the light environment will make Fe2+ in the tops more available for biochemical reactions. 相似文献
20.
The effect of ferrous (added as FeCl2) on the anaerobic co-digestion of Phragmites straw and cow dung was studied by investigating the biogas properties, pH values, organic matter degradation (COD) and enzyme activities (cellulase, protease and dehydrogenase) at different stages of mesophilic fermentation. The results showed that Fe2+ addition increased the cumulative biogas yields by 18.1 % by extending the peak period with high daily biogas yields. Meanwhile, the methane (CH4) contents in the Fe2+ added groups were generally higher than the control group before the 15th day. The pH values were not significantly impacted by Fe2+ concentrations during the fermentation process. The COD concentrations, cellulase, protease and dehydrogenase activities varied with the added Fe2+ concentrations and the stages of the fermentation process. At the beginning stage of fermentation (4th day), Fe2+ addition increased the biogas production by improving the cellulase and dehydrogenase activities which caused a decline in COD. At the peak stage of fermentation (8th day), Fe2+ addition enhanced the cellulase and protease activities, and resulted in lower COD contents than the control group. When the biogas yields decreased again (13th day), the COD contents varied similar with the protease and dehydrogenase activities, whilst cellulase activities were not sensitive to Fe2+ concentrations. At the end of fermentation (26th day), Fe2+ addition decreased the cellulase activities, led to lower COD contents and finally resulted the lower biogas yields than the control group. Taking the whole fermentation process into account, the promoting effect of Fe2+ addition on biogas yields was mainly attributed to the extension of the gas production peak stage and the improvement of cellulase activities. 相似文献