共查询到19条相似文献,搜索用时 203 毫秒
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分别对保加利亚乳杆菌ZS-2(LZS-2)进行紫外线诱变、硫酸二乙酯诱变及复合诱变,测定了突变株无细胞提取物清除DPPH自由基的能力。从诱变后的菌株中筛选出了3株对DPPH自由基清除率较高的乳酸菌UV2—6,UV5—4和D30—UV3—1。结果表明,保加利亚乳杆菌ZS-2分别经过紫外线诱变、DES、复合诱变后,选育出的突变菌株无细胞提取物对DPPH自由基清除率为56.43%,55.77%和55.60%,比出发菌株的清除率都提高了9%以上。 相似文献
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由一株枯草芽孢杆菌作为出发菌株,通过^60Coγ—DES(^60Coγ-硫酸二乙酯)进行物理化学复合诱变,采用平板酪蛋白水解圈法初筛,摇瓶复筛后,得到一株活力较出发菌株产酶活力增大44.5%的突变株。研究了发酵工艺参数对该突变菌体生长及产酶的影响,并确定了接种量1%,最佳初始pH为7.0,发酵温度为30℃的发酵工艺条件,结果证实,经过优化,可以获得较好的酶活,平均产酶能力可达到2135.43U,较原始菌株提高了59.60%。 相似文献
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以一株耐高温α-淀粉酶产生菌DG-4为出发菌株,通过紫外线(UV)诱变,得到菌株DG-4—4,酶活提高了20.4%;通过硫酸二乙酯(DES)诱变,得到菌株DG-4—46,酶活在UV诱变基础上提高了61.9%,比初始出发菌株DG-4提高了95.0%。 相似文献
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采用γ射线(Co60)及亚硝基胍复合诱变的方法对产柠檬酸黑曲霉菌株进行诱变。γ射线(Co60)诱变剂量为1400Gy,亚硝基胍的浓度为1mg/mL,作用时间为4min,在此条件进行复合诱变。经多轮筛选最终获得到一株产酸为15.5g/dL且遗传稳定性高的菌株。并对黑曲霉发酵产柠檬酸的工艺进行优化。确定种子液的最适条件:氮源选取豆饼粉,糖浓度为10%;最适发酵条件:培养温度为35℃,初始pH值5~6,氮源选取豆饼粉且氮源用量为0.8%,在50L发酵罐中进行中试试验,试验结果为周期63h,产酸17.94g/100mL,转化率为99.7%,比出发菌株发酵周期缩短3h,产酸提高10%,转化率提高5%。 相似文献
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以一株耐高温α-淀粉酶产生菌DG-4为出发菌株,通过紫外线(UV)诱变,得到菌株DG-4-4,酶活提高了20.4%;通过硫酸二乙酯(DES)诱变,得到菌株DG-4-46,酶活在UV诱变基础上提高了61.9%,比初始出发菌株DG-4提高了95.0%. 相似文献
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采用紫外、硫酸二乙酯复合诱变的方法对能选择性降解植物甾醇侧链的新金分支杆菌MN2进行诱变处理,利用梯度平板技术筛选高底物耐受性突变株,通过摇瓶发酵实验检测其转化性能,以期筛选出具有较高底物耐受性且转化生成雄烯二酮(androst-4-ene-3,17-dione,AD)能力提高的突变株。最终筛选到1 株能在含高浓度底物平板上生长的AD突变株MN4。在底物甾醇投料量为20 g/L,摇瓶发酵144 h时AD生成率为40.9%,较出发菌株提高了15.1%。经斜面接种连续传代5 次,MN4突变株遗传性状稳定。对突变株MN4的发酵培养基进行优化,通过正交试验确定的最佳培养基配比为:葡萄糖1 g/L,玉米浆25 g/L,磷酸二氢钠0.6 g/L,硝酸钠6.2 g/L,豆油160 g/L。根据该配方进行转化,得到AD的生成率为50.6%。 相似文献
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以分枝杆菌Mycobacterium sp. BD-696 为出发菌株,采用紫外、硫酸二乙酯复合诱变处理,筛选得到两株雄烯二酮高产突变株:Mycobacterium sp. BD-696-3 和Mycobacterium sp. BD-696-6,在底物甾醇添加量为6‰、摇瓶发酵168h 时的雄烯二酮产量分别为2.31g/L 和2.33g/L,得率分别为60.7% 和61.4%,较出发菌株提高了12.8%和13.5%。连续传代实验结果表明,突变株Mycobacterium sp. BD-696-6 的遗传性状稳定。 相似文献
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Recent studies showed that non-hormonal supplements such as vitamins, minerals and amino acids can contain anabolic androgenic steroids not declared on the labels of the products. These undeclared substances (often prohormones of testosterone or 19-nortestosterone) can cause health risks to consumers and might lead to positive results in sports doping control, especially for the nandrolone metabolite norandrosterone. The analysis of nutritional supplements for anabolic steroids has proven to be rather difficult due to the different matrices in the various products. To conduct a broad-based analysis, a few robust methods capable of analysing various matrices are needed. To obtain a sensitive gas chromatography-mass spectrometry (GC-MS) analysis, a method including extraction and purification of the analytes followed by GC-MS analysis of the trimethylsilyl (TMS) derivatives of the steroids was developed. The limit of detection was improved by the addition of a mixture of 1-N,N-diisopropylamino-n-alkanes (DIPAs) to the final extract. In pure creatine monohydrate powder the limits of detection were demonstrated to be 0.1 ng microg (-1) for dehydroepiandrosterone (DHEA) and estr-4-ene-3beta,17beta-diol, 0.7 ng g(-1) for 5alpha-androstane-3beta,17beta-diol and androsta-1,4-diene-3,17-dione, 1 ng g(-1) for estr-5-ene-3beta,17beta-diol, estr-4-ene-3,17-dione, 19-nortestosterone, androst-4-ene-3, 17-dione and testosterone, and 2 ng g(-1) for androst-4-ene-3beta,17beta-diol and androst-5-ene-3beta,17beta-diol. The recovery (determined at 200 ng g(-1)) ranged from 32% for 19-nortestosterone to 92% for androst-5-ene-3beta,17beta-diol. During the investigation of different nutritional supplements, several analytical difficulties occurred. Aspects of homogenization, extraction, separation, derivatization and GC-MS measurement as well as strategies for the solution of problems arising were optimized. For quantitative measurements of the steroids in nutritional supplements, deuterated internal standards of the specific steroids or standard addition are necessary to compensate for matrix effects. 相似文献
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采用紫外线照射和NTG对实验室保存的一株对植物甾醇有降解能力的Mycobacterium sp. SH5进行诱变处理,得到一株雄甾-4-烯-3,17-二酮(Androst-4-end- 3,17-dione, AD)和雄甾-1,4-二烯-3,17-二酮(Androst -1,4-end-3,17-dione, ADD)分解酶 (9α-羟化酶) 缺陷型菌株Mycobacterium sp. SH5-52.对Mycobacterium sp. SH5-52降解植物甾醇侧链得到AD (D) 的培养基组成、接种量、温度、pH值和溶氧等发酵条件进行了研究.在最佳的发酵条件下,投料质量浓度为0.6 g/dL时,AD (D) 的转化率由原来的37.2%提高到47.6%左右. 相似文献
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采用60Coγ射线、硫酸二乙酯(DES)、原生质体紫外3种诱变方法对嗜酸乳杆菌(Lactobacillus acidophilus)NX2-6进行诱变,以期获取高产类细菌素菌株。结果表明,60Coγ射线诱变的最佳辐照剂量为2.0k Gy,DES处理的最佳条件是浓度为0.7%的DES处理菌体10min,原生质体紫外诱变最佳照射时间为20s,分别得到高产菌γ56,D47和UV156,它们的抑菌效价分别为6096.78,5384.98U/m L和6230.79U/m L,是出发菌株抑菌效价(2819.36U/m L)的2.16、1.91、2.21倍。传代表明,突变株γ56、D47、UV156具有稳定的遗传性。 相似文献