利福霉素B产生菌—地中海诺卡氏菌的推理选育

利福霉素Ｂ的生物合成受芳香族氨基酸（Ｔｒｐ、Ｔｙｒ、Ｐｈｅ）的反馈抑制。用紫外线处理Ｎ．ｍｅｄｉｔｅｒｒａｎｅｉ ＸＣ－１０２菌丝悬浮液后，并在含０．１％芳香族氨基酸的琼脂平板上分离芳香族氨基酸抗性变种。结果表明，芳香族氨基酸抗性变种的发酵效价高于自然分离株和紫外线诱变株；色氨酸抗性变种（Ｔｒｐ＾ｒ）的发酵效价又高于酷氨酸抗性变种（Ｔｙｒ＾ｒ）和苯丙氨酸抗性变种（Ｐｈｅ＾ｒ）；０．５％Ｔｒｐ＾ｒ变     

Avermectin产生菌异亮氨酸诱导变种的选育

用紫外线处理ａｖｅｒｍｅｃｔｉｎ（ＡＶＭ）产生菌ＳｔｒｅｐｔｏｍｙｃｅｓａｖｅｒｍｉｔｉｌｉｓＸＣ１－２５，并在含有Ｌ－异亮氨酸（Ｌ－Ｉｌｅ）的平板培养基上筛选Ｌ－Ｉｌｅ诱导变种。结果表明：Ｉｌｅｉ变株发酵产生的ＡＶＭＢ１ａ效价高于自然分离株与紫外线诱变株，其中Ｉｌｅｉ变株ＸＣ２－２６的ＡＶＭＢ１ａ效价较亲株提高２２％。该变株经自然分离获得菌株ＸＣ３－８，其ＡＶＭＢ１ａ效价比出发菌株提高５０％以上，传代试验表明菌株ＸＣ３－８的形态和高产性能稳定，它在７ｍ３发酵罐生产试验，产生ＡＶＭＢ１ａ效价与发酵指数均比出发菌株提高５６％。     

螺旋霉素高产菌种的推理选育

根据螺旋霉素的生物合成途径对螺旋霉素产生菌产二素链霉菌进行推理选育，并获得了高产菌种。首先在紫外线诱变的基础上，筛选豆油耐性变株，得到菌株ＸＣ２－３７，其发酵效价较出发菌株ＸＣ１－２９提高９％。通过培养基优化，菌株ＸＣ２－３７的发酵效价提高６１．８％。再以紫外线处理菌株ＸＣ２－３７，并筛选缬氨酸诱导变株，得到菌株ＸＣ３－１１，其发酵效价较菌株ＸＣ２－３７提高２０％。菌株ＸＣ３－１１经自然分离得到菌株ＸＣ４－１８，发酵效价达到４５００ｕ／ｍｌ，为原始出发菌株ＸＣ１－２９的２．２５倍。传代试验表明菌株ＸＣ４－１８的高产遗传特性稳定。菌株ＸＣ４－１８应用于５０ｍ３发酵罐进行工业化生产，与原始出发菌株ＸＣ１－２９相比，发酵效价和发酵指数分别提高８４．９％和４３．６％。     

吉他霉素高产菌株的选育

以吉他霉素产生菌Ｒ－０１－１０５菌株为出发菌株，经紫外线、Ｃｏ６０、色氨酸、异亮氨酸和２－ＤＯＧ复合处理，获得４株高产突变株，其中Ｔ－１１－１２０的摇瓶效价（１５３０２ｕ／ｍｌ）比出发菌株（８５００ｕ／ｍｌ）提高８０．１％，在１０吨发酵罐上连续８批验证，平均发酵效价１２３８８ｕ／ｍｌ，比原生产水平（７４００ｕ／ｍｌ）提高６７．４％，并且质检全部合格，对生产实际具有重要意义     

万古霉素产生菌的选育

以东方拟无枝酸菌（Amycolatopsisoriental）05—12为出发菌株,经紫外线（15W。253．7nm,距离18cm,照射5m）诱变处理,在含庆大霉素1000μg·mL^-1的浓度梯度平板上筛选庆大霉素抗性变株,得到一株万古霉素高产交株（Amyeolatopsisoriental）06-4。其摇瓶效价较出发菌株提高23％．对万古霉素的抗性提高200％。传代试验表明该变株的高产性能遗传特性较稳定。用正交试验法对万古霉素发酵培养基进行了优化,与原发酵培养基相比,万古霉素的摇瓶发酵效价提高了13．4%。     

万古霉素产生菌的选育与发酵培养基优化

万古霉素产生菌东方拟无枝酸菌（Amycolatopsis orientalis）5－13经紫外线（30W，253.7nm，距离30cm，照射50s）诱变后，在含万古霉素1000μg/ml的浓度梯度平板上筛选万古霉素抗性变株，得到一株万古霉素抗性变株A.orientalis 6-21，其摇瓶效价较出发菌株提高23％，对万古霉素的抗性提高200％。传代试验表明该变株的高产性能遗传特性较稳定。用正交试验法对万古霉素发酵培养基进行了优化，与原发酵培养基相比，万古霉素的摇瓶发酵效价提高了14.3%。     

原生质体再生与诱变在硫霉素产生菌选育中的应用

以硫霉素产生菌卡特利链霉菌３５８（Ｓｔｒｅｐｔｏｍｙｃｅｓｃａｔｌｅｙａ３５８）为原始菌株,用原生质体形成与再生结合物理、化学诱变的方法进行菌种选育。在最适条件下原生质体释放浓度和再生率分别为１．６×１０９／ｍｌ和２９．５％。原生质体再生处理后,硫霉素产量变异向正方向移动,筛选到１株ＰＲ－１１７,相对效价提高６０％。分别以菌株ＰＲ－１１７的孢子和原生质体进行紫外线及亚硫酸氢钠诱变,原生质体对诱变剂的敏感性强于孢子,致死率增加,效价分布更分散。原生质体与孢子紫外线诱变正变率分别为１６．５％和９％,亚硫酸氢钠诱变的正变率都为４％。从原生质体紫外线诱变株中筛选到１株ＰＲｕ－３３６,相对效价比原始菌株提高９０％。     

应用环丙沙星乳剂治疗烫伤大鼠铜绿假单胞菌感染

采用大鼠１５％深Ⅲ度烫伤铜绿假单胞菌感染模型,动态观察了１％磺胺嘧啶银（ＳＤ－Ａｇ）,０．５％环丙沙星（ＣＰＬＸ）及２％ＣＰＬＸ的治疗效果。伤口细菌量和体内白细胞量的检测结果显示,在抵抗铜绿假单胞菌和提高大鼠生存率方面,２％ＣＰＬＸ优于１％ＳＤ－Ａｇ和０．５％ＣＰＬＸ,与对照组比较有显著性差异（Ｐ＜０．００１）。     

L-赖氨酸产生菌钝齿棒杆菌高产突变株 EB_(0.04-14)的选育

以赖氨酸产生菌钝齿棒杆菌（ｃｏｒｙｎｅｂａｃｔｅｒｉｕｍｃｒｅｎａｔｕｍ）Ｅ０．８－２６（ＨＳ＋，ＡＥＣｒｒ，Ｍｅｔｒ，ＴＡｒ，ＥＳｒ）为出发菌种，对菌体进行氯化锂加紫外线、博来霉素三重复合处理，经初筛、复筛，获得一株高产菌株ＥＢ０．０４－１４，其发酵液中Ｌ－赖氨酸含量较出发菌株提高１７．７％．在发酵至２８ｈ时，加入０．２％的吐温８０或０．３％的二甲基亚砜，分别又使Ｌ－赖氨酸产量提高１６．５％和１６．３％．通过使用表面活性剂来改变细胞质膜透性，可使产酸量大幅度提高．     

多粘菌素E高产菌株的选育

以多粘类芽胞杆菌（Paenibacillus polymyxa）18－3为出发菌株，采用紫外线诱变，并以重金属Cu^2 作为筛选因子，获得一株遗传稳定且多粘菌素E发酵效价比出发菌株提高45％的菌株。对该菌株再采用亚硝基胍（NTG）诱变，以缬氨酸结构类似物α－氨基丁酸作为筛选因子时得到一株产量提高34％的菌株。     

螺旋霉素产生菌螺旋霉素链霉菌遗传育种

本文是利用抗生素抗性与产量之间的相关性来进行螺旋霉素产生菌螺旋霉素链霉菌的遗传育种,旨在获得高效价菌株,从而提高螺旋霉素的生产水平。首先用正交试验法确定出发菌株最佳发酵培养基,并在此基础上通过紫外线诱变,和在螺旋霉素浓度梯度平板上筛选螺旋霉素抗性菌株。按上述方法理性化筛选得到的菌株多为正突变株。从本实验得到一株螺旋霉素抗性菌株SPM~r-248,其抗性较出发菌株提高300％,生产能力较出发菌株提高81.3％。菌株SPM~r-248的高效价生产性能遗传特性稳定。在7m~3罐做发酵放大,与出发菌株相比,发酵效价提高31.4％,发酵指数提高18.8％,具有一定的学术意义和经济价值。     

A genetic approach to the biosynthesis of the rifamycin-chromophore in Nocardia mediterranei. I. Isolation and characterization of a pentose-excreting auxotrophic mutant of Nocardia mediterranei with drastically reduced rifamycin production

The mutant under study, designated A8, is derived from a Nocardia mediterranei strain, N813, which is a high rifamycin B producer. A8 is auxotrophic for aromatic amino acids and produces much less rifamycin B than the parent. A mixture of pentoses with D (--) ribulose as the main product is accumulated in the fermentation broth of this mutant. It was shown to be affected in its transketolase activity as no formation of D-sedoheptulose -7P from pentose-phosphates could be detected in vitro using crude extracts. The only pathway so far known which is derived from D-sedoheptulose-7P is the shikimate pathway leading to aromatic amino acids and vitamins. Biochemical and genetic investigations with mutant A8, which is defective in both the biosynthesis of rifamycins and the biosynthesis of shikimate pathway products, show that the seven-carbon amino unit of the rifamycin-chromophore must be derived from an intermediate of the shikimate pathway.     

A genetic approach to the biosynthesis of the rifamycin-chromophore in Nocardia mediterranei. II. Isolation and characterization of a shikimate excreting auxotrophic mutant of Nocardia mediterranei with normal rifamycin-production

The mutant under study, designated A10, is derived from a Nocardia mediterranei strain, N813, which is a high rifamycin B producer. A10 is auxotrophic for aromatic amino acids but unlike A8 (see preceding paper) produces the same amount of rifamycin B as the parent. Shikimic acid and 3-dehydroshikimic acid are accumulated in the fermentation broth of this mutant. It was shown to be blocked in one of the enzymes leading from shikimate to chorismate. No formation of shikimate-3-phosphate from shikimate and ATP could be detected in vitro using crude extracts of this mutant and of the parent. As mutant A10 is only defective in the biosynthesis of aromatic amino acids and not in the biosynthesis of rifamycins it would appear that the seven-carbon amino unit of the rifamycin-chromophore must be derived from an intermediate of the shikimate pathway not behind shikimate. By referring to the results of the preceding paper it can be seen that the origin of this moiety can definitely be localized between 3-deoxy-D-arabinoheptulosonic acid-7-phosphate and shikimate.     

组合链霉素和利福平抗性突变去甲基万古霉素高产菌株的选育

在去甲基万古霉寨生产菌株东方拟无枝酸菌的菌种选育中。利用核糖体工程育种方法，筛选得到的新菌株在发酵水平以及改善气丝及孢子生长贫瘠方面均有较大提高。首轮采用链霉素抗性筛选，得到突变株3．30，斜面外观丰满程度明显好于原对照株，发酵效价提高11．9％；第二轮组合链霉素和利福平抗性结合高能电子诱变育种，进一步巩固了育种成效，得到一系列代谢特点呈多样性的菌株，其中04-102发酵水平较原出发菌株提高45．8％，代谢速度加快，传代稳定性亦得到显著改善。     

头孢菌素C产生菌顶头孢霉理性化筛选的研究

顶头孢霉82-128菌株改良过程中,除常规的随机筛选外,还采用了理性化筛选,以提高头孢菌素C的产量,方法为筛选营养缺陷型回复突变株及抗重金属离子变株.试验结果表明理化筛选优于随机筛选.正突变频率前者为50.87%,后者为38.25%.变株幅度,前者产量高于亲株200%的占6.16%,高于亲株300%的占2.84%;后者产量高于亲株200%的占0.258%,高于亲株300%的未出现.     

庆大霉素生物合成基因簇中抗性基因gmrB及gmrA的功能研究

目的 研究绛红色小单孢菌(Micromonospora purpurea)G1008中抗性基因gmrB与gmrA功能,为阐明庆大霉素生物合成机制奠定基础。方法 以红霉素抗性基因ermE分别置换gmrB和gmrA基因,构建突变株GerB102和GerA102。借助TLC和MS分析突变株代谢产物是否变化,同时检测突变株耐受自身代谢产物的能力是否发生变化。结果 突变株GerB102代谢产物没有发生明显变化,仍主要积累庆大霉素C化合物,而GerA102代谢产物发生变化。庆大霉素耐受性试验结果显示,GerB102和G1008耐庆大霉素浓度达到6000U/mL以上,而GerA102不足50U/mL。结论 gmrB既非庆大霉素生物合成的关键基因,也非关键的抗性基因,而gmrA是庆大霉素抗性的关键基因。     

复合诱变法选育普那霉素高产菌株

以始旋链霉菌(Streptomyces pristinaespiralis)ZP2为出发菌株,经紫外线(UV)、亚硝基胍(NTG)复合诱变,并结合普那霉素抗性突变株的理化筛选,选育到一株高产突变菌株UN2056,其普那霉素产量达到1490 mg/L,比出发菌株提高了45.7%.传代试验表明该高产突变菌株的高产性能遗传特性稳定.高产突变株UN2056在5 L发酵罐中进行发酵试验,其平均发酵产量达到1645 mg/L,比出发菌株提高了60.8%.     

Effect of methionine on cephalosporin C and penicillin N production by a mutant of Cephalosporium acremonium.

A mutant with enhanced potential to utilize sulfate for cephalosporin C production was isolated from a strain of Cephalosporium acremonium. The mutant displayed potency levels more than twofold that of the parent in the presence of sulfate but its productivity was severely inhibited by more than 0.5% of methionine which gave high cephalosporin C production with the parent. In a complex medium norleucine stimulated cephalosporin C production by the mutant in the presence of sulfate, whereas it showed no effect on the parent. In an incubation system with sulfur-starved cells of the mutant, L-methionine, but not the D-isomer, gave lower cephalosporin C production and a delayed production of penicillin N. However, it exhibited a stimulatory effect in the presence of valine or alpha-aminoadipic acid, the constituent amino acids of the antibiotic. Norleucine showed a similar effect to that of L-methionine in the presence of sulfate. On the basis of these results, characteristics of the mutant are discussed in connection with the effect of methionine.     

利福霉素B产生菌的推理选育

利福霉素B由地中海拟分枝酸菌产生，本文对工业生产菌株A.mediterraneiX1－02进行进一步筛选。采用推理选育的方法使产生菌减轻由芳香族氨基酸（色氨酸（tup）、苯丙氨酸、酪氨酸)和对羟基苯甲酸（PHBA，pbh）引起的对利福霉素B生成合成的反馈抑 制作用，并提高对前体丙酸（prp）的耐受量。通过UV诱变提高诱变株的耐受性，获得了高产菌株A.mediterraneiXC9－25（trp′，phb′，prp′），其生产能力达到10000u/ml，较原始出发菌株A.mediterraneiX1－02提高了1．385倍。动力学试验结果利用福霉素B的生物合成与菌体生长不同步，属于非生长偶联型。