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排序方式: 共有145条查询结果,搜索用时 31 毫秒
61.
Ainon Hamzah Chia-Wei Phan Pek-Hoon Yong Nurul Hayati Mohd Ridzuan 《Soil & Sediment Contamination》2014,23(7):751-762
Contamination of soil by petroleum hydrocarbons is becoming prevalent in Malaysia. Infiltration of soil contamination into groundwater poses a great threat to the ecosystem and human health. Bioremediation can occur naturally or can be enhanced with supplementation of microorganisms and fertilizers. However, fertilizers are expensive and therefore alternative nutrient-rich biomaterials are required. In this study, two organic wastes from agricultural industry (i.e., sugarcane bagasse and oil palm empty fruit bunch) were investigated for possible enhanced bioremediation of soil contaminated with Tapis crude oil. Two bacterial strains isolated and characterized previously (i.e., Pseudomonas aeruginosa UKMP-14T and Acinetobacter baumannii UKMP-12T) were used in this study. Sugarcane bagasse (5% and 15%, w/w) and oil palm empty fruit bunch (20%, w/w) were mixed with soil (500 g) spiked with Tapis crude oil (3%, v/w). The treated soils as well as controls were incubated for 20 days under controlled conditions. Sampling was carried out every four days to measure the number of bacterial colonies (CFU/g) and to determine the percentage of oil degradation by gas chromatography. The two biostimulating agents were able to maintain the soil moisture holding capacity, pH, and temperature at 38-40% volumetric moisture content (VMC), 7.0, and 29–30°C; respectively. The growth of bacteria consortium after 20 days in the treatment with sugarcane bagasse and oil palm empty fruit bunch had increased to 10.3 CFU/g and 9.5 CFU/g, respectively. The percentage of hydrocarbon degradation was higher in the soil amended with sugarcane bagasse (100%) when compared to that of oil palm empty fruit bunch (97%) after 20 days. Our results demonstrated the potential of sugarcane bagasse and oil palm empty fruit bunch as good substrates for enhanced bioremediation of soil contaminated with petroleum crude oil. 相似文献
62.
Mário A. Alves da Cunha Attilio Converti Júlio C. dos Santos Silvio S. da Silva 《World journal of microbiology & biotechnology》2006,22(1):65-72
Summary A new PVA-hydrogel matrix for yeast cell immobilization for xylitol bioproduction from sugarcane bagasse was studied. Five
repeated-batch fermentation runs were carried out in medium based on sugarcane bagasse hemicellulosic hydrolysate with reuse
of the entrapped biocatalyst. The system performance as well as the metabolic behaviour of cells entrapped into the matrix
were evaluated. The biocatalyst remained stable and exhibited a similar fermentative profile in all the successive batches,
demonstrating the viability of the system. At the end of the run, an average xylitol production was observed of 35.1 g l−1 and average xylitol yield and productivity of 0.58 g g−1 and 0.49 g l−1 h−1, respectively. 相似文献
63.
João Paulo L. Franco Cairo Leandro C. Oliveira Cristiane A. Uchima Thabata M. Alvarez Ana Paula da S. Citadini Júnio Cota Flávia Costa Leonardo Ana M. Costa-Leonardo Marcelo F. Carazzolle Fernando F. Costa Gonçalo A.G. Pereira Fabio M. Squina 《Insect biochemistry and molecular biology》2013,43(10):970-981
Termites can degrade up to 90% of the lignocellulose they ingest using a repertoire of endogenous and symbiotic degrading enzymes. Termites have been shown to secrete two main glycoside hydrolases, which are GH1 (EC 3.2.1.21) and GH9 (EC 3.2.1.4) members. However, the molecular mechanism for lignocellulose degradation by these enzymes remains poorly understood. The present study was conducted to understand the synergistic relationship between GH9 (CgEG1) and GH1 (CgBG1) from Coptotermes gestroi, which is considered the major urban pest of São Paulo State in Brazil. The goal of this work was to decipher the mode of operation of CgEG1 and CgBG1 through a comprehensive biochemical analysis and molecular docking studies. There was outstanding degree of synergy in degrading glucose polymers for the production of glucose as a result of the endo-β-1,4-glucosidase and exo-β-1,4-glucosidase degradation capability of CgEG1 in concert with the high catalytic performance of CgBG1, which rapidly converts the oligomers into glucose. Our data not only provide an increased comprehension regarding the synergistic mechanism of these two enzymes for cellulose saccharification but also give insight about the role of these two enzymes in termite biology, which can provide the foundation for the development of a number of important applied research topics, such as the control of termites as pests as well as the development of technologies for lignocellulose-to-bioproduct applications. 相似文献
64.
An extracellular alkaline carboxymethycellulase (CMCase) from Bacillus subtilis was purified by salt precipitation followed by anion-exchange chromatography using DEAE-Sepharose. The cell-free supernatant containing crude enzyme had a CMCase activity of 0.34 U/mg. The purified enzyme gave a specific activity of 3.33 U/mg, with 10-fold purification and an overall activity yield of 5.6%. The purified enzyme displayed a protein band on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) with an apparent molecular size of 30 kDa, which was also confirmed by zymogram analysis. The enzyme displayed multisubstrate specificity, showing significantly higher activity with lichenan and β-glucan as compared to carboxymethylcellulose (CMC), laminarin, hydroxyethylcellulose, and steam-exploded bagasse, and negligible activity with crystalline substrate such as Avicel and filter paper. It was optimally active at pH 9.2 and temperature 45°C. The enzyme was stable in the pH range 6–10 and retained 70% activity at pH 12. Thermal stability analysis revealed that the enzyme was stable in temperature range of 20°C to 45°C and retained more than 50% activity at 60°C for 30 min. The enzyme had a Km of 0.13 mg/ml and Vmax of 3.38 U/mg using CMC as substrate. 相似文献
65.
J. J. Muso Cachumba R. Terán Hilares L. P. Brumano P. R. F. Marcelino F. A. F. Antunes J. C. Santos 《Preparative biochemistry & biotechnology》2013,43(4):328-333
AbstractL-asparaginase is an important enzyme used in the pharmaceutical and food industry, which can be produced by different microorganisms using low cost feedstocks. In this work, sugarcane bagasse (SCB) was used as support for enzyme production in solid-state fermentation (SSF) by A. terreus. Initially, the influence of the variables carbon and nitrogen sources on the enzyme production was studied following an experimental design carried out in Erlenmeyer flasks. Statistical analysis indicated the use of 0.54% of starch, 0% of maltose, 0.44% of asparagine, and 1.14% of glutamine in the medium, resulting in enzyme activity per volume of produced extract of 120.723?U/L. Then, these conditions were applied in a horizontal column reactor filled with SCB, producing 105.3?U/L of enzyme activity. Therefore, the potential of extracellular L-asparaginase enzyme production in the column reactor using sugarcane bagasse as support was demonstrated and it represents a system that can favor large scale production. 相似文献
66.
AbstractBioethanol production from agro-industrial residues is gaining attention because of the limited production of starch grains and sugarcane, and food–fuel conflict. The aim of the present study is to maximize the bioethanol production using cassava bagasse as a feedstock. Enzymatic liquefaction, by α-amylase, followed by simultaneous saccharification and fermentation (SSF), using glucoamylase and Zymomonas mobilis MTCC 2427, was investigated for bioethanol production from cassava bagasse. The factors influencing ethanol production process were identified and screened for significant factors using Plackett–Burman design. The significant factors (cassava bagasse concentration (10–50?g/L), concentration of α-amylase (5–25% (v/v), and temperature of fermentation (27–37?°C)) were optimized by employing Box–Behnken design and genetic algorithm. The maximum ethanol concentrations of 25.594?g/L and 25.910?g/L were obtained from Box–Behnken design and genetic algorithm, respectively, under optimum conditions. Thus, the study provides valuable insights in utilizing the cost-effective industrial residue, cassava bagasse, for the bioethanol production. 相似文献
67.
In this study, the production of sugar monomers from sugarcane bagasse (SCB) by sono-assisted acid hydrolysis was performed. The SCB was subjected to sono-assisted alkaline pretreatment. The cellulose and hemicellulose recovery observed in the solid content was 99% and 78.95%, respectively and lignin removal observed during the pretreatment was about 75.44%. The solid content obtained was subjected to sono-assisted acid hydrolysis. Under optimized conditions, the maximum hexose and pentose yield observed was 69.06% and 81.35% of theoretical yield, respectively. The hydrolysate obtained was found to contain very less inhibitors, which improved the bioethanol production and the ethanol yield observed was 0.17 g/g of pretreated SCB. 相似文献
68.
This study aimed to determine the effect of moisture content of three different feedstocks on overall ethanol yield. Switchgrass and sugarcane bagasse from two sources were either soaked in water (∼80% moisture) or left dry (∼12% moisture), and half each of these were impregnated with 3% w/w SO2 and all were steam pretreated. The twelve resulting substrates were compared based on overall sugar recovery after pretreatment, cellulose conversion following enzymatic hydrolysis, and ethanol yield following simultaneous saccharification and fermentation. The overall ethanol yield after simultaneous saccharification and fermentation of hexoses was 18-28% higher in samples that were soaked prior to SO2 addition than in SO2-catalyzed samples that were not soaked. In samples that were uncatalyzed, soaking made little difference, indicating that the positive effect of increased moisture content may be related to increased permeability of the biomass to SO2. 相似文献
69.
The chemical characteristics, enzymatic saccharification, and ethanol fermentation of autohydrolyzed lignocellulosic material
that was exposed to steam explosion were investigated using bagasse as the sample. The effects of the steam explosion on the
change in pH, organic acids production, degrees of polymerization and crystallinity of the cellulose component, and the amount
of extractive components in the autohydrolyzated bagasse were examined. The steam explosion decreased the degree of polymerzation
up to about 700 but increased the degree of crystallinity and the micelle width of the cellulose component in the bagasse.
The steam explosion, at a pressure of 2.55 MPa for 3 mins, was the most effective for the delignification of bagasse. 40 g/L
of glucose and 20 g/L of xylose were produced from 100 g/L of the autohydrolyzed bagasse by the enzymatic saccharification
using mixed cellulases, acucelase and meicelase. The maximum ethanol concentration, 20 g/L, was obtained from the enzymatic
hydrolyzate of 100 g/L of the autohydrolyzed bagasse by the ethanol fermentation usingPichia stipitis CBS 5773; the ethanol yield from sugars was 0.33 g/g sugars. 相似文献
70.