梅岭霉素产生菌抗药性突变标志诱变筛选模型的初步研究

本文通过梅岭霉素 (Meilingmycin)产生菌南昌链霉菌NS 4 1 80菌株孢子对 6种抗生素敏感性测定 ,采用诱变剂EMS四种不同诱变剂量对菌株孢子进行诱变处理 ,诱变处理的孢子涂布在含致死浓度链霉素的高氏平板上。然后从抗药性突变标志菌株中进一步筛选梅岭霉素高产菌株。在 150 0多个抗药性突变株中通过初筛获得了比诱变出发菌株的产素能力提高 50 %以上菌株。通过诱变剂量分别与抗药性突变率和突变株产素产量的变势统计分析表明 ,菌株抗药性突变与产素突变密切相关 ,产素突变的EMS诱变剂量高于抗药性突变诱变剂量 ,在 0 .0 3mol/LEMS剂量作用下 ,菌株致死率为 99.4 3% ,抗药性突变率为 0 .0 4 4 0 % ,建立了梅岭霉素产生菌抗药性突变标志诱变推理性筛选模型。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。     

快中子辐射在抗生素产生菌育种上的应用

自1945年Myers和Hanson用回旋加速器产生的中子处理青霉素产生菌以来,快中子辐射已成为微生物诱变处理的一种手段。本文着重介绍快中子辐射在抗生素产生菌育种上的一些应用及其研究成果。     

紫外诱变选育恩拉霉素高产菌株

本研究采用紫外诱变育种技术对一株产恩拉霉素抗真菌链霉菌(Streptomyces fungicidicus)F110进行了诱变处理,经链霉素抗性、利福霉素B抗性以及双重抗性筛选,共获得了132株抗生素抗性突变株,其中26株突变菌株的恩拉霉素产量与出发菌株相比均有明显提高。摇瓶发酵条件下,突变株SR93的恩拉霉素产量最高可达2 400μg/m L,与出发菌株相比提高了38%。传代结果表明:该突变株产素水平稳定,因此具备较好的开发及工业应用价值。     

农用抗生素产生菌菌种选育的研究进展

农用抗生素产生菌的原始菌株 ,往往产量很低或质量较差 ,不能满足工业生产的需要 ,必须对它的某些性状进行改良。改良菌种的主要手段是通过育种 ,筛选出高产菌株。传统的诱变育种是最广泛的选育方法 ,以基因工程为核心的现代生物技术也应用于农用抗生素产生菌的菌种选育中 ,并逐渐成为农用抗生素菌种选育的主导技术。     

快中子辐射处理卡那霉素产生菌

快中子辐射用于抗生素产生菌的诱变育种已有报道。我们在北京辐射中心的协作下,从1976年开始,用400千电子伏高压倍加器产生的14MEV快中子,处理卡那霉素产生菌,获得一些高产菌株。本文报道这方面的试验结果。     

低能离子注入在CGTase高产菌株选育中的应用

应用能量30keV、剂量为5×1015N /cm2的离子注入对环糊精葡萄糖基转移酶产生菌进行诱变育种,得到液体发酵24h产酶高于出发株50%以上的菌株11株。5代传代试验表明诱变后得到的高产菌株产酶具有较好的传代稳定性。     

L-精氨酸产生菌诱变育种的研究

本文报道了L-精氢酸产生菌诱变育种的研究结果。以谷氨酸产生菌钝齿棒状杆菌AS1．542为出发菌株,经亚硝基胍多次逐级诱变,获得了一株能够积累大量L-精氨酸的菌株971.1。该菌属于组氢酸缺陷型,并具有对磺胺孤的抗药性。在以葡萄糖为碳源、硫酸铵为氮源的培养基中直接发酵四天,产酸最高可达25·2 mg／ml,并具有较高的产酸稳定性。     

支链氨基酸合成调控机制及菌种选育策略研究进展

提高国内支链氨基酸产生菌的高产菌株选育水平有助于缩短与国外生产之间的差距,满足国内市场需求。根据支链氨基酸生物合成途径及代谢调节,重点阐述了合成过程中关键酶的代谢调控,介绍了诱变育种、代谢工程、基因组改组及全局转录机器工程四种育种策略的研究进展。在支链氨基酸选育方面,全局转录机器工程育种目前虽无成功实例,但具有很大的潜力,而其他育种策略在氨基酸的选育中均发挥重要作用,可供国内相关育种工作者参考使用。     

微生物育种物理诱变技术ARTP的应用进展

微生物物理诱变育种技术广泛应用于改善微生物菌种特性、提高微生物产品产量与质量,并且在生物燃料和生物修复方面也具有重要的应用价值。本文重点介绍常压室温等离子体(ARTP)物理诱变技术在微生物诱变育种方面的应用,其对具有重要工农业应用价值的产芽孢菌种具有明显的诱变优越性。进一步分析了微生物物理诱变育种技术未来的发展趋势和重要应用前景,为微生物物理诱变育种工作提供借鉴。     

用快中子法选育细菌脂肪酶高产菌株

研究了从土壤中筛选产脂肪酶的菌株,利用紫外线,快中子,快中子和磁场复合,γ射线,γ射线和磁场复合诱变,以酶活为筛子进行诱变育种,结果,出发菌酶活较低的一株得到了一株酶活为396．22U/mL的诱变株,此酶活比出发菌株高92倍,并发现比菌对紫外线和快中子比较敏感,而出发菌酶活较高的一株得到了酶活为424．60U/mL发酵液的诱变株,此酶活为出发菌株3．0倍,在此基础上,初步探讨了快中子,γ射线及磁场复合处理在产脂肪酶菌种诱变中的作用,并认为,在产脂肪酶菌株的诱变中快中子诱变更为有效。     

微生物技术去除抗生素残留污染的研究进展

抗生素进入环境会对生物造成深远的影响,如何去除抗生素的残留引起许多国家的关注。抗生素在环境中主要发生生物降解,而具有抗性的微生物菌株发挥主要的功效,因此近些年利用微生物技术处理抗生素残留污染成为研究热点。本文对具有抗生素降解功能的微生物资源和利用复合菌系处理抗生素残留的生物技术进行概括总结,并对微生物处理技术的不足和发展方向进行展望。     

Antibacterial activity of rifampicin against the causative agents of suppurative, septic diseases]

The antibacterial activity of rifampicin was studied in comparison with other antibiotics with respect to clinical strains isolated from cases with various purulent inflammatory processes caused by Staphylococcus, E. coli, Ps. aeruginose, Proteus. The aim of the study was to define the role of rifampicin in the treatment of the above infections. No rifampicin resistant strains were found among staphylococci belonging to the phenotype carrying the determinants of resistance to 2-8 antibiotics. Rifampicin was less active against gramnegative organisms. High heterogeneity of the microbial population of rifampicin was shown with respect to all microbial strains tested. The rate of the spontaneous mutants was high. The average rate of the mutants was 1-7.7-10-8. The studies on the dynamics of the rifampicin resistance increase in the strains of Staphylococci, E. Coli, Ps. aeruginosa and Proteus showed that the resistance increased after 1-2 passages, which means that one-stage mutation was characteristic rifampicin.     

重离子诱变微生物育种的研究进展

近年来,重离子束作为一种新的辐射诱变源在微生物育种领域已多有应用。与传统的辐照源相比,重离子束具有更高的传能线密度,可以产生更强的辐射损伤生物效应,因此突变效率高。本文综述了近年来重离子诱变在微生物育种中取得的进展、诱变后突变体菌株的筛选策略、重离子束引起微生物遗传物质改变的直接和间接机制以及突变后的修复机理,并对其在微生物育种中存在的问题进行了探讨。     

微生物脂肪酶的研究进展

详细综述了脂态酶微生物产生菌的选育、诱变育种及发酵生产技术,对微生物脂肪酶的性质、分离、纯化、固定化技术及应用进行了简要概述     

产β-内酰胺酶金黄色葡萄球菌的耐药分析

目的对产β-内酰胺酶金黄色葡萄球菌的标本分布和药物敏感试验进行分析,为临床使用抗生素提供依据。方法按照《全国临床检验操作规程》的要求接种．对分离出的220株金黄色葡萄球菌（Sta phylococcs aureus,Sau）,用头孢菌素显色法测定其β-内酰胺酶。结果220株金黄色葡萄球菌中产β-内酰胺酶171株,产酶率为77．7％,产酶株除对万古霉素、替考拉宁、利福平及复方新诺明敏感外,对其它的抗生素均呈现不同程度耐药,其中青霉素G、氨苄西林耐药率均为99．4％,红霉素为86．1％。结论产β-内酰胺酶株对青霉素类、大环内酯类抗生素呈现高度耐药,临床治疗不宜使用此类抗生素,提示临床选择药物时,应在药敏试验的指导下合理选择抗生素。     

微生物发酵生产5-氨基乙酰丙酸研究进展

5-氨基乙酰丙酸是生物体内吡咯生物合成途径的关键中间产物,具有广泛的应用前景。文中从三方面归纳了国内外关于5-氨基乙酰丙酸的最新研究进展:生产5-氨基乙酰丙酸的微生物筛选分离与诱变;基于C4途径的微生物全细胞生物转化合成5-氨基乙酰丙酸;基于微生物代谢工程改造构建高产5-氨基乙酰丙酸的工程菌株。最后,预测了未来5-氨基乙酰丙酸的研究方向和焦点。     

Effect of intercalating dyes on the production of antibiotics by Micromonospora rosaria and Micromonospora purpurea.

The effect of treatment with various intercalating dyes on the ability to produce antibiotics in Micromonospora rosaria and Micromonospora purpurea was studied. Treatment with acriflavine resulted in a high frequency loss of antibiotic productivity in both species. In M. rosaria, the loss of antibiotic-producing ability appeared to be strain-dependent. In M. purpurea, up to 90% of colonies were found to have lost gentamicin-producing ability when protoplasts were used in the test. These antibiotic-nonproducing strains were further studied. The following observations were made: (1) Unlike the producing ability, the resistance to the antibiotics is a very stable character in both species. (2) Protoplast fusion analysis indicates that rosamicin-nonproducing characteristics of MR 217-AF2 and MR 217-AF3 strains induced by the acriflavine treatment is due to chromosomal mutation or rearrangement but not to loss of a plasmid. (3) Gentamicin-nonproducing strains of M. purpurea responded differently to the supplementation of streptamine or DOS in the culture medium. When supplemented with streptamine or DOS, some of these strains regained the ability to produce antibiotic, showing that the biosynthesis of intermediate was affected in these strains.     

红树林样品不经分离的微生物群体培养物生物活性研究

从海南、广西与广东三省的红树林区采集了181个样品,不进行微生物分离而直接作发酵剂接种到发酵培养基进行发酵,取发酵上清液进行抗细菌、抗真菌与肿瘤细胞毒活性的测定。同时对样品进行可培养微生物的分离与生物活性测定。结果显示:不同样品类型的生物活性差异较大。在15个具有强抗活性的样品中,有5个样品分离到的单株菌均无任何生物活性,说明这5个样品的生物活性可能是由微生物的群体作用产生的,也可能是某种没有培养出的微生物产生的。初步表明了探索微生物混合培养获得生物活性代谢产物的可能性。     

Resistance to antibacterial drugs of Enterobacteriaceae isolated from healthy children and from those with Salmonella infections

A total of 2329 Enterobacteriaceae strains in bacterial associations isolated from healthy children and children with salmonellosis were tested for their resistance to antimicrobial drugs. It was shown that the aerobic microbial associations isolated from the healthy children contained higher numbers of strains sensitive or resistant to 1-3 antibiotics while the microbial associations from the children patients with salmonellosis treated with antibiotics contained higher numbers of strains resistant to 6-8 antibiotics. Resistance of the aerobic bacterial associations was mainly defined by resistance of E. coli and K. pneumoniae. The feces of the healthy children never treated with antimicrobial drugs contained strains resistant to them. The use of the antibiotics in the treatment led to increasing numbers of the resistant bacteria and changing species composition of the bacterial associations.     

Insecticidal Bacillus thuringiensis silences Erwinia carotovora virulence by a new form of microbial antagonism, signal interference

It is commonly known that bacteria may produce antibiotics to interfere with the normal biological functions of their competitors in order to gain competitive advantages. Here we report that Bacillus thuringiensis suppressed the quorum-sensing-dependent virulence of plant pathogen Erwinia carotovora through a new form of microbial antagonism, signal interference. E. carotovora produces and responds to acyl-homoserine lactone (AHL) quorum-sensing signals to regulate antibiotic production and expression of virulence genes, whereas B. thuringiensis strains possess AHL-lactonase, which is a potent AHL-degrading enzyme. B. thuringiensis did not seem to interfere with the normal growth of E. carotovora; rather, it abolished the accumulation of AHL signal when they were cocultured. In planta, B. thuringiensis significantly decreased the incidence of E. carotovora infection and symptom development of potato soft rot caused by the pathogen. The biocontrol efficiency is correlated with the ability of bacterial strains to produce AHL-lactonase. While all the seven AHL-lactonase-producing B. thuringiensis strains provided significant protection against E. carotovora infection, Bacillus fusiformis and Escherichia coli strains that do not process AHL-degradation enzyme showed little effect in biocontrol. Mutation of aiiA, the gene encoding AHL-lactonase in B. thuringiensis, resulted in a substantial decrease in biocontrol efficacy. These results suggest that signal interference mechanisms existing in natural ecosystems could be explored as a new version of antagonism for prevention of bacterial infections.