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Twelve samples derived from different locations in south central area of China are treated by enrichment and spread-plate
technique for initial screening. Seven chitinase-producing strains are isolated. The chitinase present in the culture supernatant
of strain CS-01 possesses the maximum activity of 0.118 U/mL. Analysis of the morphological feature and the ITS rDNA sequence
reveals that strain CS-01 belongs to Aspergillus fumigatus. Production of the chitinase is regulated by a inducible way and the maximum activity appears at 36 h in colloidal chitin
culture. Purification of the chitinase is carried out by salting out, gel filtrate chromatography and anion exchange chromatography
sequentially. Native-PAGE and SDS-PAGE indicate that the chitinase from A. fumigatus CS-01 is a monomer with the relative molecular mass estimated to be 4.50×104. Its maximum activity appears at pH 5 and 55 °C. The chitinase is stable at pH 4.0–7.5 and below 45 °C.
Foundation item: Projects(50621063, 50674101) supported by the National Natural Science Foundation of China 相似文献
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A new strain named YTW315 was isolated from Dexing area using the double-layer culture technique. The morphological, biochemical and physiological characteristics of YTW315 were studied. Physiological investigation indicates that the strain YTW315 is a strict (obligate) chemolithoautotroph, metabolizing ferrous iron and pyrite. The optimal growth conditions for the strain are 40 ℃ and pH 1.6. A phylogenetic analysis based on 16S rRNA sequences shows that the isolate is clustered to Leptospirillum ferriphilum with 99.8% similarity to Leptospirillum ferriphilum strain Fairview and ATCC 49881. The molar fraction of DNA (G+C) of the isolate is 58.1%. The strain can tolerate high concentration of Fe(Ⅲ) and As(V) (500 mmol/L and 50 mmol/L, respectively). Bioleaching experiment indicates that the strain can oxidize Fe(Ⅱ) efficiently, and after 30 d, 44.56% of copper and 95.31% of iron are extracted from chalcopyrite and pyrite, respectively. 相似文献
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为了校验并解决进线档最小相间距离的工程实际问题,建立进线档相导线的任意一点三维数学模型,通过改进粒子群算法,快速精确计算进线档相邻两相的最小相间距离。运用MATLAB程序仿真分析了相邻相的最小相间距离与档距、相导线张力、挂点高差的关系。仿真结果表明随着档距的增大,相邻两相的最小相间距离增加较快,随后增加趋势变缓;相邻两相的最小相间距离随着某一控制相的导线张力变大而减小;相邻两相的最小相间随挂点高差的增大而迅速减小。最后指出,敏感因素均有一临界值,超过该临界值,相邻两相的最小相间距离不满足合格距离要求。 相似文献
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输电线路的杆塔规划问题是一个由简单不等式约束的多维、非线性最优化问题,且不能保证其目标函数连续或可导,故传统的算法如穷举法、试凑法、解析法等求解均有较大局限性。为了解决上述问题,采用改进单纯形算法结合外点法罚函数求解此类问题,结果表明,算法辅以将约束条件作为指数罚函数的外点法构造增广目标函数,可以方便地处理各项约束条件的限制,计算效率高,鲁棒性强,程序实现简单。同时,文中采用的算法对于可能出现的局部最优解可以根据工程经验加以判别和剔除,适用性强。 相似文献
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