In this study, a xylanase-produeing Aspergillus niger strain, NS-1, was screened and isolated from agricultural and forestry wastes. Based on single-fac- tor experiments, the effects of different carbon sources, compo...In this study, a xylanase-produeing Aspergillus niger strain, NS-1, was screened and isolated from agricultural and forestry wastes. Based on single-fac- tor experiments, the effects of different carbon sources, composite carbon sources, nitrogen sources, calcium carbonate concentrations, initial pH and surfactants on xylanase production by A. niger NS-1 were investigated. The results indicated that the most appropriate carbon source was corncobs ; the best composite carbon source was corncobs ＋ xylan, which was conducive to xylanase secretion; the most suitable nitrogen source was ammonium sulfate. Xylanase activity reached the highest in the medium added with 1.5% calcium carbonate and SDS as a surfactant with an initial pH of 5.0. This study provided the basis for the production of high-activity xylanase.展开更多
Objective: To study the optimal medium composition for xylanase production by Aspergillus niger XY-1 in solid-state fermentation (SSF). Methods: Statistical methodology including the Plackett-Burman design (PBD) and t...Objective: To study the optimal medium composition for xylanase production by Aspergillus niger XY-1 in solid-state fermentation (SSF). Methods: Statistical methodology including the Plackett-Burman design (PBD) and the central composite design (CCD) was employed to investigate the individual crucial component of the medium that significantly affected the enzyme yield. Results: Firstly, NaNO3, yeast extract, urea, Na2CO3, MgSO4, peptone and (NH4)2SO4 were screened as the significant factors positively affecting the xylanase production by PBD. Secondly, by valuating the nitrogen sources effect, urea was proved to be the most effective and economic nitrogen source for xylanase production and used for further optimization. Finally, the CCD and response surface methodology (RSM) were applied to determine the optimal concentration of each sig-nificant variable, which included urea, Na2CO3 and MgSO4. Subsequently a second-order polynomial was determined by multiple regression analysis. The optimum values of the critical components for maximum xylanase production were obtained as follows: x1 (urea)=0.163 (41.63 g/L), x2 (Na2CO3)=?1.68 (2.64 g/L), x3 (MgSO4)=1.338 (10.68 g/L) and the predicted xylanase value was 14374.6 U/g dry substrate. Using the optimized condition, xylanase production by Aspergillus niger XY-1 after 48 h fermentation reached 14637 U/g dry substrate with wheat bran in the shake flask. Conclusion: By using PBD and CCD, we obtained the optimal composition for xylanase production by Aspergillus niger XY-1 in SSF, and the results of no additional expensive medium and shortened fermentation time for higher xylanase production show the potential for industrial utilization.展开更多
Cassava (Manihot esculenta, Crantz) is one of the most important food plants in West Africa. Its peels are made up of cellulose, hemicellulose and lignin. This lignocellulolytic biomass can be converted using microbia...Cassava (Manihot esculenta, Crantz) is one of the most important food plants in West Africa. Its peels are made up of cellulose, hemicellulose and lignin. This lignocellulolytic biomass can be converted using microbial enzymes to fermentable sugars which have wide range of biotechnological relevance in many fermentation processes. The aim of this study is to screen filamentous fungi from decaying cassava peels that are good producers of xylanases and cellulases. Decaying parts of cassava peels were obtained and brought to the laboratory for further work. Fungi were isolated, identified and screened for cellulase and xylanase production. Isolate with highest frequency of occurrence and enzyme production was identified using phenotypic and molecular method. Optimisation of growth conditions for enzymes production was monitored using the DNSA method, also saccharification of cassava peel were carried out using the enzymes obtained from the isolate. Aspergillus terreus KJ829487 was the predominant fungus. It produces cellulases and xylanases optimally at 40°C, pH 6 and 8, utilising carboxymethylcellulose (CMC) or xylose and yeast extracts as its carbon and nitrogen sources respectively. Saccharification of the peels yielded 584 mg/L glucose, 78 mg/L xylose and 66 mg/L rhamnose. Aspergillus terreus KJ829487 obtained from cassava peels have the ability to produce high concentration cellulases and xylanases which effectively hydrolysed the lignocelluloses’ biomass to fermentable sugars.展开更多
With the high availability of agricultural wastes in Malaysia, green energy is practical to be conducted. Thus, a research on the modification of the physical conditions of the solid state culture system, specifically...With the high availability of agricultural wastes in Malaysia, green energy is practical to be conducted. Thus, a research on the modification of the physical conditions of the solid state culture system, specifically different initial moisture content, fermentation temperature, inoculums size and different percentage of carbon and nitrogen sources were conducted to compare the usage of two different lignocellulosic materials which were oil palm frond and banana petiole respectively. After using a conventional method （one factor at a time）, the optimum fermentation conditions would be a combination of 70% initial moisture content （v/w）, at 28 ~C fermentation temperature with supplementation of 1% sucrose （w/w） and 1% peptone using 1 mL of inoculum in order to achieve highest xylanase production which was 1,711.87 U/mL and 1,579.60 U/mL for oil palm frond and banana petiole respectively. It was suggested that oil palm frond showed higher xylanase production compared to banana petiole.展开更多
As a new mutagenetic method, low-energy ion implantation has been used widely in many research areas in recent years. In order to obtain some industrial strains with high xylanase yield, the wild type strain Aspergill...As a new mutagenetic method, low-energy ion implantation has been used widely in many research areas in recent years. In order to obtain some industrial strains with high xylanase yield, the wild type strain Aspergillus niger A3 was mutated by means of nitrogen ions implantation （10 keV, 2.6× 10^14 ～ 1.56 × 10^15 ions/cm^2） and a mutant N212 was isolated subsequently. However, it was found that the initial screening means of the high-yielding xylanase strains such as transparent halos was unfit for first screening. Compared with that of the wild type strain, xylanase production of the mutant N212 was increased from 320 IU/ml to 610 IU/ml, and the optimum fermentation temperature was increased from 28 ℃ to 30 ℃.展开更多
With ion implantation (N+, energy 10 keV and dosage 1.56×1015 N+cm-2), a high xylanase-producing strain Aspergillus niger N212 was selected. Based on an orthogonal experiment, an optimal fermentation condition wa...With ion implantation (N+, energy 10 keV and dosage 1.56×1015 N+cm-2), a high xylanase-producing strain Aspergillus niger N212 was selected. Based on an orthogonal experiment, an optimal fermentation condition was designed for this high-yield strain. The suitable medium was composed of 8% corncob; 1.0% wheat bran; 0.1%TWEEN20; 0.5% (NH4)2SO4; 0.5%NaNO3; 0.5%FeSO4, 7.5 × 10-4; MnSO4·H2O, 2.5 × 10-4; ZnSO4, 2.0 × 10-4; CoCl2, 3.0 × 10-4. At present, under our experiment condition, xylanase activity of Aspergillus niger N212 reached a level of 600 IU/ml, almost increased by 100% in xylanase production and the time of yielding xylanase was largely reduced to 12 h at 28℃.展开更多
基金Supported by Project of Taizhou Science and Technology Bureau(TS019)
文摘In this study, a xylanase-produeing Aspergillus niger strain, NS-1, was screened and isolated from agricultural and forestry wastes. Based on single-fac- tor experiments, the effects of different carbon sources, composite carbon sources, nitrogen sources, calcium carbonate concentrations, initial pH and surfactants on xylanase production by A. niger NS-1 were investigated. The results indicated that the most appropriate carbon source was corncobs ; the best composite carbon source was corncobs ＋ xylan, which was conducive to xylanase secretion; the most suitable nitrogen source was ammonium sulfate. Xylanase activity reached the highest in the medium added with 1.5% calcium carbonate and SDS as a surfactant with an initial pH of 5.0. This study provided the basis for the production of high-activity xylanase.
基金Project (No. 2004C32049) supported by the Science and Technology Department of Zhejiang Province, China
文摘Objective: To study the optimal medium composition for xylanase production by Aspergillus niger XY-1 in solid-state fermentation (SSF). Methods: Statistical methodology including the Plackett-Burman design (PBD) and the central composite design (CCD) was employed to investigate the individual crucial component of the medium that significantly affected the enzyme yield. Results: Firstly, NaNO3, yeast extract, urea, Na2CO3, MgSO4, peptone and (NH4)2SO4 were screened as the significant factors positively affecting the xylanase production by PBD. Secondly, by valuating the nitrogen sources effect, urea was proved to be the most effective and economic nitrogen source for xylanase production and used for further optimization. Finally, the CCD and response surface methodology (RSM) were applied to determine the optimal concentration of each sig-nificant variable, which included urea, Na2CO3 and MgSO4. Subsequently a second-order polynomial was determined by multiple regression analysis. The optimum values of the critical components for maximum xylanase production were obtained as follows: x1 (urea)=0.163 (41.63 g/L), x2 (Na2CO3)=?1.68 (2.64 g/L), x3 (MgSO4)=1.338 (10.68 g/L) and the predicted xylanase value was 14374.6 U/g dry substrate. Using the optimized condition, xylanase production by Aspergillus niger XY-1 after 48 h fermentation reached 14637 U/g dry substrate with wheat bran in the shake flask. Conclusion: By using PBD and CCD, we obtained the optimal composition for xylanase production by Aspergillus niger XY-1 in SSF, and the results of no additional expensive medium and shortened fermentation time for higher xylanase production show the potential for industrial utilization.
文摘Cassava (Manihot esculenta, Crantz) is one of the most important food plants in West Africa. Its peels are made up of cellulose, hemicellulose and lignin. This lignocellulolytic biomass can be converted using microbial enzymes to fermentable sugars which have wide range of biotechnological relevance in many fermentation processes. The aim of this study is to screen filamentous fungi from decaying cassava peels that are good producers of xylanases and cellulases. Decaying parts of cassava peels were obtained and brought to the laboratory for further work. Fungi were isolated, identified and screened for cellulase and xylanase production. Isolate with highest frequency of occurrence and enzyme production was identified using phenotypic and molecular method. Optimisation of growth conditions for enzymes production was monitored using the DNSA method, also saccharification of cassava peel were carried out using the enzymes obtained from the isolate. Aspergillus terreus KJ829487 was the predominant fungus. It produces cellulases and xylanases optimally at 40°C, pH 6 and 8, utilising carboxymethylcellulose (CMC) or xylose and yeast extracts as its carbon and nitrogen sources respectively. Saccharification of the peels yielded 584 mg/L glucose, 78 mg/L xylose and 66 mg/L rhamnose. Aspergillus terreus KJ829487 obtained from cassava peels have the ability to produce high concentration cellulases and xylanases which effectively hydrolysed the lignocelluloses’ biomass to fermentable sugars.
文摘With the high availability of agricultural wastes in Malaysia, green energy is practical to be conducted. Thus, a research on the modification of the physical conditions of the solid state culture system, specifically different initial moisture content, fermentation temperature, inoculums size and different percentage of carbon and nitrogen sources were conducted to compare the usage of two different lignocellulosic materials which were oil palm frond and banana petiole respectively. After using a conventional method （one factor at a time）, the optimum fermentation conditions would be a combination of 70% initial moisture content （v/w）, at 28 ~C fermentation temperature with supplementation of 1% sucrose （w/w） and 1% peptone using 1 mL of inoculum in order to achieve highest xylanase production which was 1,711.87 U/mL and 1,579.60 U/mL for oil palm frond and banana petiole respectively. It was suggested that oil palm frond showed higher xylanase production compared to banana petiole.
基金the National Key Technologies R & D Program of China during the 10th Five-Year Plan(No.2001BA302B)
文摘As a new mutagenetic method, low-energy ion implantation has been used widely in many research areas in recent years. In order to obtain some industrial strains with high xylanase yield, the wild type strain Aspergillus niger A3 was mutated by means of nitrogen ions implantation （10 keV, 2.6× 10^14 ～ 1.56 × 10^15 ions/cm^2） and a mutant N212 was isolated subsequently. However, it was found that the initial screening means of the high-yielding xylanase strains such as transparent halos was unfit for first screening. Compared with that of the wild type strain, xylanase production of the mutant N212 was increased from 320 IU/ml to 610 IU/ml, and the optimum fermentation temperature was increased from 28 ℃ to 30 ℃.
文摘With ion implantation (N+, energy 10 keV and dosage 1.56×1015 N+cm-2), a high xylanase-producing strain Aspergillus niger N212 was selected. Based on an orthogonal experiment, an optimal fermentation condition was designed for this high-yield strain. The suitable medium was composed of 8% corncob; 1.0% wheat bran; 0.1%TWEEN20; 0.5% (NH4)2SO4; 0.5%NaNO3; 0.5%FeSO4, 7.5 × 10-4; MnSO4·H2O, 2.5 × 10-4; ZnSO4, 2.0 × 10-4; CoCl2, 3.0 × 10-4. At present, under our experiment condition, xylanase activity of Aspergillus niger N212 reached a level of 600 IU/ml, almost increased by 100% in xylanase production and the time of yielding xylanase was largely reduced to 12 h at 28℃.
