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从万古霉素抗性突变体中筛选碱性纤维素酶高产菌株 总被引:2,自引:0,他引:2
以芽胞杆菌 X—6 为出发菌株,经甲基磺酸乙酯( E M S) 和紫外线( U V) 复合诱变,选育万古霉素抗性突变体。研究结果表明,抗药性突变株碱性羧甲基纤维素酶( C M Case) 产量提高的正变率和正变幅度明显高于非抗药性菌株。从抗性突变株中获得 E V23 菌株,其产酶活力比出发株 X—6 提高320 % ,酶活力达353u/ ml。 相似文献
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复合诱变黑曲霉选育β—葡萄糖苷酶高产菌株 总被引:22,自引:0,他引:22
对黑曲霉原生质体进行紫外、LiCl复合诱变,观察诱变后原生质体再生菌落,发现了孢子色变异较大的菌株,且其变化与酶产量相关。经发酵筛选,获得β-葡萄糖苷酶活较高菌株,其酶活由出发菌株的10u/ml提高到14.7u/ml。再对高产突变株进行氮离子注入,酶活又提高20%(达17u/ml)。 相似文献
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对黑曲霉原生质体进行紫外、LiCl复合诱变,观察诱变后原生质体再生菌落,发现了抱子颜色变异较大的菌株,且其变化与酶产量相关。经发酵筛选,获得卜葡萄糖昔酶活较高菌株,其酶活由出发菌株的10u/ml提高到14.7u/ml。再对高产突变株进行氮离子注入,酶活又提高20%(达17u/ml)。 相似文献
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柚苷酶产生菌的选育及发酵条件研究 总被引:17,自引:0,他引:17
根据柚皮苷的物理及化学特性,设计和试验了一种新的柚苷酶产生菌筛选模型。在153株曲霉中筛选到一株产柚苷酶菌株AspergillusnigerZG84,摇瓶发酵酶活力为320u/ml。经自然分离和DES诱变处理,得到ZG86菌株,酶活力达1124u/ml。对其培养条件和产酶条件进行了研究。 相似文献
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高活力碱性淀粉酶菌种的选育及培养条件研究 总被引:2,自引:0,他引:2
通过对产碱性淀粉酶芽胞杆菌B-9545进行紫外线、原生质体亚硝基胍复合诱变等反复处理,获得一株具有较高碱性淀粉酶活力的变异株PN-6。产酶活力从540u/ml提高到780u/ml,确定的最佳培养条件是:pH8-10,30℃培养48h。从变异株和出发菌株的生长及产酶曲线看到,变异株的生长速度低于出发菌株,其产酶高峰与出发菌株相比略拖后一段时间,但是酶活力要远大于出发菌株。 相似文献
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芽孢杆菌x-6菌株经甲基磺酸乙酯(EMS)和紫外线(UV)复合诱变,以其万古霉素抗性突变体中选育获得一突变株EV23,所产生的纤维素酶碱性酶,且酶活力由原来的0.84U/ml提高到3.53U/ml,EV23菌株基本上组成性地合成碱性羧甲基纤维素酶(CMCase)酶合成明显表现出抗降解物阻遏的特点,以葡萄糖为碳源培养,4%浓度时酶合成水平达最高,酶合成与生长几乎同时发生,合成效率受菌体生长速率影响较 相似文献
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在前面研究的基础上,仍采用黑曲霉突变株WMC-15为产酶菌株,对糖化生产和提取工艺进行了较大的改进,提高了菌株的产酶缩短了发酵时间,提高回收率,大幅度降离糖化酶的生产成本,按最佳的培养基配方和发酵工艺条件,采用突变株WMC-15仅发酵96小时左右,酶活力可达25,000u/ml以上,对提高我国的糖化酶活力及设备利用率都具有现实意义。 相似文献
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Patricia Espinoza Eduardo Bárzana Mariano García-Garibay Lorena Gόmez-Ruiz 《Biotechnology letters》1992,14(11):1053-1058
Summary Five strains ofK. marxianus were evaluated for the production of intracellular lactase, intra and extracellular pectinase and intra and extracellular inulinase. The strain NRRL-Y-1109 showed the highest lactase activity, but the strain CDBB-L-278 produced notably higher activities of inulinase and pectinase than the rest of the strains tested. The strain CDBB-L-278 was selected for the simultaneous production of two enzymes. Two enzymes fermentations were achieved with productions of 44% lactase and 53% pectinase, or 26% lactase and 47% inulinase compared to the single enzyme levels. 相似文献
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为了提高游离果胶酶的稳定性,对罗布麻脱胶具有特异性的枯草芽孢杆菌(FM208849)进行产果胶酶发酵时,采用交联酶聚集体(CLEAs)技术制备固定化果胶酶,并对交联果胶酶聚集体的制备条件、酶学性质进行研究。结果表明,游离果胶酶经80%饱和硫酸铵沉淀后,在30℃,经4%的戊二醛溶液交联135 min,所形成的交联果胶酶聚集体的活回收率为61.5%,其最适反应温度45℃和最适pH10,在对交联果胶酶聚集体的热稳定性和有机溶剂稳定性分析中,均显示了比游离酶更高的稳定性。 相似文献
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我国果胶酶制剂使用广泛但专一性不高,高效、专一的果胶酶制剂在市场上仍然匮乏。利用基因工程技术改造果胶酶生产菌株——黑曲霉来生产单一成分的果胶酶成为解决果胶酶应用需求的一种有效方案。构建一种高效的CRISPR-Cas9基因编辑技术,可为构建高产单一性果胶酶的黑曲霉底盘菌株提供有效的基因编辑工具。首先敲除产果胶酶黑曲霉基因组上的pyrG基因构建尿嘧啶营养缺陷型菌株AnΔpyrG,并在AnΔpyrG菌株的pyrG基因位点定点整合Cas9基因表达盒和pyrG基因表达盒,构建组成型表达Cas9基因的黑曲霉菌株AnCas9,再构建含有gpdA启动子、锤头结构核酶、HDV核酶的稳定性表达sgRNA的pLM2-sgRNA质粒,建立CRISPR-Cas9基因编辑体系。利用该技术失活AnCas9菌株中的2个聚半乳糖醛酸酶基因4978020和4983861来检测构建的CRISPR-Cas9基因编辑效率并检测4978020基因功能缺失菌株的表型变化和产酶变化,结果表明果胶酶基因编辑效率大于50%,AnΔ4978020的表型和果胶酶酶活性与出发菌株均无明显变化。在黑曲霉中成功构建了高效的Cas9基因编辑技术,4978020基因功能缺失也不影响菌株表型,为构建高产单一性果胶酶黑曲霉底盘菌株奠定基础。 相似文献
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Genetic diversity of Harpins from Xanthomonas oryzae and their activity to induce hypersensitive response and disease resistance in tobacco 总被引:6,自引:0,他引:6
LI Ping LU Xuzhong SHAO Min LONG Juying & WANG Jinsheng Department of Plant Pathology Nanjing Agricultural University Key Laboratory of Monitoring Management of Plant Disease Pests Ministry of Agriculture Nanjing China 《中国科学:生命科学英文版》2004,47(5):461-469
The hrp (hypersensitive response and patho-genicity) gene clusters in Gram-negative phytopatho-genic bacteria determine hypersensitive response (HR) in non-host plants and pathogenicity in host plants of the bacteria[1—3]. An hrp gene cluster usually contains genes coding for the components of the type Ⅲ se-cretion pathway, effectors and the proteins that regu-late the productions and transportations of effectors[4]. Many effectors such as Harpins and Avr proteins are believed secreted by … 相似文献
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Xanthomonadins are yellow, membrane-bound pigments produced by members of the genus Xanthomonas. We identified an ethyl methanesulfonate-induced Xanthomonas oryzae pv. oryzae mutant (BXO65) that is deficient for xanthomonadin production and virulence on rice, as well as auxotrophic for aromatic amino acids (Pig(-) Vir(-) Aro(-)). Reversion analysis indicated that these multiple phenotypes are due to a single mutation. A genomic library of the wild-type strain was used to isolate a 7.0-kb clone that complements BXO65. By transposon mutagenesis, marker exchange, sequence analysis, and subcloning, the complementing activity was localized to a 849-bp open reading frame (ORF). This ORF is homologous to the aroE gene, which encodes shikimate dehydrogenase in various bacterial species. Shikimate dehydrogenase activity was present in the wild-type strain and the mutant with the complementing clone, whereas no activity was found in BXO65. This clone also complemented an Escherichia coli aroE mutant for prototrophy, indicating that aroE is functionally conserved in X. oryzae pv. oryzae and E. coli. The nucleotide sequence of the 2.9-kb region containing aroE revealed that a putative DNA helicase gene is located adjacent to aroE. Our results indicate that aroE is required for normal levels of virulence and xanthomonadin production in X. oryzae pv. oryzae. 相似文献