利福霉素B的选育及其发酵的研究

目的：寻找新的菌种提高利福霉素B的发酵水平。方法：对菌株AmediterraneiXCl—02进行筛选、诱变,获得新的菌株。结果：获得高产菌株AmediterraneiXC9—25,生产能力较原始出发菌株AmediterraneiXCl—02提高1．385倍,效价达到10000u／ml。结论：通过工业方法产生菌株,并对其进行筛选变种是提高利福霉素B生产能力的有效途径。     

利福霉素B发酵放大I．从摇瓶到15L发酵罐的发酵放大

研究了溶氧和剪切力对地中海拟分枝酸菌XC－925发酵产生利福霉素B的影响，并对利福霉素B从摇瓶到15L发酵罐的发酵放大及15L发酵罐流加补料发酵进行了研究。利用摇瓶研究结果表明地中海拟分枝酸菌XC－925发酵产生利福霉素B时对溶氧要求较高，而对剪切力不太敏感。以溶氧为依据，在15L发酵罐间歇发酵过程中，控制溶氧不低于25％，利福霉素B的发酵效价可达到1000u/ml左右，发酵周期（6d）较摇瓶发酵缩短了1d。15L发酵罐如采用流加补料发酵工艺，利福霉素B的发酵效价还会有较大幅度提高。     

通过获得链霉素抗性基因(str)突变株筛选梅岭霉素高产菌株

本文通过链霉素对梅岭霉素（meilingmycin）产生菌南昌链霉菌NS－41－80菌株孢子致死浓度的测定，采用诱变剂EMS四种不同诱变剂量对菌株的孢子进行诱变处理，诱变处理的孢子涂布在含链霉素致死浓度的高氏平板上，获得了大量的链霉素抗性基因（str）突变株。然后从链霉素抗性基因突变株进一步筛选到梅岭霉素高产菌株80－5．11－221，在摇瓶条件下，只产梅岭霉素不产南昌霉素，梅岭霉素活性效价达1500μg/ml，比出发菌株NS－41－80的摇瓶发酵效价855μg/ml提高了77．9％，该菌株连续传代六代进行摇瓶发酵，其F2代和F3代梅岭霉素发酵效价稳定，F4代至F6代随着传代数增加，其梅岭霉素发酵效价急速下降。通过EMS诱变剂量分别与抗药性突变率和链霉素抗性基因突变株产梅岭霉素产量的产势统计分析表明，菌株抗药性突变与产抗生素突变密切相关，产抗生素突变的EMS诱变剂量高于链霉素抗性基因突变诱变剂量。在0．03mol/L的EMS剂量作用下，菌株致死率为99．43％，而抗药性突变率为0．0440％，建立了梅岭霉素产生菌链霉素抗性基因突变筛选方法，为南昌链霉菌高产菌种选育研究作了有益的尝试，并有助于其它链霉菌属的抗生素产生菌育种研究。     

利福霉素产生菌的推理选育

用超声波处理利福霉素产生菌地中海诺卡氏菌所得的菌丝片断比石英砂处理所得菌丝片断的敏感性高。将超声波处理所得的菌丝片断,经UV诱变处理后,菌株分别经L—色氨酸、氯化铯等类似物做耐受性处理,获得利福霉素SV的高产菌株,产量提高10％左右。     

康乐霉素产生菌─—地中海诺卡氏菌康乐变种的分类鉴定

康乐霉素属于利福霉素族，其Ａ成份是一种新抗生素。康乐霉素产生菌１７４７－６４是从广州康乐县土壤中分离出来的，根据分类研究，菌株应归属于诺卡氏菌，是地中海诺卡氏菌的一新变种，定名为地中海诺卡氏菌康乐变种１７４７－６４（Ｎｏｃａｒｄｉａｍｅｄｉｔｅｒｒａｎｅｉｖａｒ．ｋａｎｇｌｅｎｓｉｓ１７４７－６４）。     

国外利福霉素类抗菌素的发展概况及其衍生物的临床评价

一、概况 1.利福霉素类抗菌素的发现及其微生物来源利福霉素类抗菌素是1957年意大利Lepetit公司从法国土壤中分离的地中海链丝菌(Streptomyces mediterranei)产生得到的抗菌素。他们费了四年时间,收集了世界各地2000只土壤标本,从链丝菌中分离了18,000株,由此选出了产生菌,发现该产生菌的发酵液对革兰氏阳性菌及结核分枝杆菌具有强的杀菌作用。产生菌在含有巴比妥酸衍生物培养基中得到的培养液经纸上层析,分离得到A、B、C、D、E五种成份,仅利福霉素B得到了结晶,是稳定的物质,毒性低。1964年日本找到了产生利福霉素O的产生菌。利福霉素B很容易转变     

利福霉素生物合成的进展

引言利福霉素产生菌于1957年首先由意大利米兰 Leptit 研究室从法国南部拉斐尔植物园的土壤中分离获得。该菌经鉴定为地中海诺卡氏菌(Nocardia mediterranea),在普通的培养基中至少可产生5个组份,称为利福霉素 A、B、C、D 和 E,其中仅 B 可被精制。它的活性较小,但通过化学方法使其“活化”,包括氧化利福霉素 B 为利福霉素 O,然后水解为活性高的利福霉素 S,并继续还原为利福霉素 SV,它们的结构见图1。     

由地中海诺卡氏菌的一株重组体产生新利福霉素

在产生抗生素新衍生物的放线菌研究中,采用遗传操作创造新遗传型的有效法有三种,即突变、重组和质粒转移。已有研究指出,地中海诺卡氏菌(N.mediterranei)突变后得到许多生物合成障碍突变型菌株,这样的菌株只能合成利福霉素B的各种前体物利福霉素SV、W和I,而不能合成利福霉素B,这些前体物被认为是新的利福霉素。地中海诺卡氏菌遗传重组是用两株营养缺陷型进行的,一个亲株产生利福霉素B和另一株产生利福霉素W之间的种内重组,筛选     

无机氮对利福霉素B生物合成的影响

用于生物合成过程培养基的氮的形式,对生物合成抗生素影响很大。有机氮和无机氮对微生物的生长和抗生素的大量合成作用极大。无机氮在培养基中的形式,取决于产生抗生素的微生物特性。所以,铵氮用于链霉素、庆大霉素生产菌,氧化形氮用于albo·mycin和新生霉素生产菌,而无机氮源对林可霉素生产菌则起抑制作用。利福霉素B通常使用的无机氮源为硫酸铵。本文研究各种形式的无机氮源对利福霉素B生物合成的影响。利福霉素B生产菌为Nocardia medite-rranei1536菌株。实验培养基用豆粉作有机氮     

微波诱变及添加氯化镧筛选阿扎霉素B高产菌株

目的 拟通过微波诱变和添加氯化镧对阿扎霉素B产生菌N98-1634进行选育,获得高产菌株.方法 对菌株进行40～240s的微波诱变,采用金黄色葡萄球菌抑菌圈法获得初筛通过株,并进行HPLC复筛获得高产菌株;在高产菌株发酵培养基中加入5～30mg/L的氯化镧考查其对阿扎霉素B合成的影响.结果 通过微波诱变选出l株阿扎霉素B产量达到945.0μg/mL的突变菌株MW-638,较出发菌株N98-1634的752.4μg/mL提高了25.6％,随后经过添加15mg/L氯化镧阿扎霉素B单位最终达到1413.8μg/mL.结论 微波诱变对提高菌株N98-1634阿扎霉素B发酵单位效果明显,诱变菌株添加适量氯化镧可以显著提高其产量.     

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.     

New insights into rifamycin B biosynthesis: isolation of proansamycin B and 34a-deoxy-rifamycin W as early macrocyclic intermediates indicating two separated biosynthetic pathways

Proansamycin B, the formerly postulated intermediate of rifamycin B biosynthesis, was isolated from cultures of the Amycolatopsis mediterranei mutant F1/24. The structure was determined using UV, IR, NMR and MS techniques. Biotransformation studies demonstrate that proansamycin B is an intermediate of a shunt pathway, a 8-deoxy variant, of rifamycin B biosynthesis leading to 8-deoxy-rifamycin B as the final product. In addition, 34a-deoxy-rifamycin W, the direct precursor of rifamycin W, could be isolated representing the earliest macrocyclic intermediate obtained so far in the biosynthetic route to rifamycin B. Furthermore, the new rifamycin W-28-desmethyl-28-carboxy and rifamycin W-hemiacetal, intermediates in the transformation sequence of rifamycin W to rifamycin S, were isolated. Application of proton NMR measurements (double resonance and ROESY experiments) on the latter compound indicated that the stereochemistry at the chiral center C-28 is R.     

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.     

利福霉素产生菌发酵培养基的研究

本文考查了各种无机、有机氮源和黄豆饼粉酶解液对地中海诺卡氏菌(Nocardiamediterranei)C_(?)-8菌株生物合成利福霉素SV的影响。结果以蛋白胨、硝酸钾的效果为最佳。通过均匀设计的实验,获得了最佳发酵培养基的组成,使利福霉素SV的产量提高30%.     

Thioesterases and the premature termination of polyketide chain elongation in rifamycin B biosynthesis by Amycolatopsis mediterranei S699

The role of two thioesterase genes in the premature release of polyketide synthase intermediates during rifamycin biosynthesis in the Amycolatopsis mediterranei S699 strain was investigated. Creation of an in-frame deletion in the rifR gene led to a 30 approximately 60% decrease in the production of both rifamycin B by the S699 strain or a series of tetra- to decaketide shunt products of polyketide chain assembly by the rifF strain. Since a similar percentage decrease was seen in both genetic backgrounds, we conclude that the RifR thioesterase 2 is not involved in premature release of the carbon chain assembly intermediates. Similarly, fusion of the Saccharopolyspora erythraea DEBS3 thioesterase I domain to the C-terminus of the RifE PKS subunit did not result in a noticeable increase in the amount of the undecaketide intermediate formed nor in the amounts of the tetra- to decaketide shunt products. Hence, premature release of the carbon chain assembly intermediates is an unusual property of the Rif PKS itself.     

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．ｍｅｄｉｔｅｒｒａｎｅｉＸＣ－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（Ｔｒｐｒ）的发酵效价又高于酪氨酸抗性变种（Ｔｙｒｒ）和苯丙氨酸抗性变种（Ｐｈｅｒ）；０．５％Ｔｒｐｒ变种比０．１％Ｔｒｐｒ变种更高产。其中０．５％Ｔｒｐｒ变种ＸＣ－５４０的生产能力较出发菌株ＸＣ－１０２增加４２．１６％。传代试验表明ＸＣ－５４０的遗传特性稳定，在７ｍ３罐做发酵放大，与出发菌株相比，发酵效价和发酵指数分别提高５１．１１％和５１．０２％。     

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％。     

微生物来源的Xa因子抑制剂F02-2172的研究

利用一种由本中心建立的Xa因子抑制剂高通量体外筛选模型，从大量真菌菌库及其来源的代谢产物中筛选到了一株可产生阳性活性化合物的菌株F02ZA-2172，该菌株的发酵液经有机溶剂提取、硅胶柱色谱、ODS柱色谱、Sephadex LH-20柱色谱及HPLC制备分离，得到F02-2172A、B和C三个活性化合物。经紫外、质谱、核磁等理化数据分析，确定这三个化合物分别与已知化合物6-epi-ophiobolinK、ophiobolin K和ophiobolin G的结构相同，但该类化合物对Xa因子的抑制活性至今未见报道。