聚乙烯醇（PVA）降解菌的筛选、鉴定和降解特性研究

在有聚乙烯醇（PVA）污染的环境中分离到一株能降解PVA的放线菌。该菌能在以PVA为惟一碳源的无机盐培养基中生长。采用16SrDNA序列分析法，并结合常规生理生化鉴定方法对该菌进行鉴定。16SrDNA序列分析结果表明，该菌与委内瑞拉链霉菌（Streptomyces venezuelae）、砖红链霉菌（Streptomyces lateritius）和脱叶链霉菌（Streptornyc exfoliatus）有最高同源性，达到99％；通过进一步的菌株培养特征及生理生化鉴定表明该菌株与Streptomyces venezudae最接近。因此，初步判定该菌株属于Streptomyces venezuelae，并将其命名为Streptomyces sp PVA。     

蓝莓溃疡病生防链霉菌CX3的抑菌效果及其鉴定

[目的]为了明确从吉林省长白山保护区池西保护站马鞍山云杉人工林林下土壤分离,所获得1株拮抗菌株(编号记为CX3)的生防效果及分类地位。[方法]分别采用平板对峙法和杯碟法测定该菌株活菌及其发酵液的抑菌活性和抑菌谱;并通过形态学、生理生化特征、16S rRNA序列分析等方法研究了其分类地位。[结果]该菌株对13种供试植物病原菌均有抑制作用,抑菌谱广,其中对蓝莓溃疡病菌有极强的抑制作用,抑菌带达25.91 mm,发酵液的抑菌圈直径达31.73 mm;根据其菌株形态、生理生化特性、16S rRNA序列比对,最终鉴定菌株为链霉菌属Streptomyces sp.。[结论]该菌株对蓝莓溃疡病菌有显著的抑制效果,应用开发前景良好,此次是国内首次报道该菌株杀真菌活性。     

采用紫外线连续诱变方法选育阿维菌素高产菌株

以除虫链霉菌（Streptomyces avermitilis）为出发菌株,采用连续3次紫外诱变,同时使用D-脱氧葡萄糖进行定向筛选,选育得到阿维菌素高产菌株,较出发菌株提高了34.4%。     

轮丝链霉菌(Streptomyces Ys.03)代谢产物的抗植物病毒活性及其分类鉴定

[目的]1株从土壤中分离得到的放线菌的抗植物病毒活性及其分类鉴定。[方法]室内对峙培养、枯斑和系统寄主的保护及治疗试验,菌株形态观察并结合培养特征、生理生化性状及16S rDNA序列测定。[结果]菌株Ys.03对蜡状芽孢杆菌有稳定的拮抗作用;发酵液与烟草花叶病毒(TMV)混合后接种枯斑和系统寄主,对TMV抑制率分别为95.01%和88.67%;接种前、后叶面分别喷施发酵液抑制率均较高;菌株孢子链轮生,16S rDNA测序与师岗轮丝链霉菌(Streptomyces mormookaensis)同源性达100%。[结论]菌株Ys.03代谢产物对TMV有显著的抑制作用,鉴定为链霉菌属轮生类群师岗轮丝链霉菌。     

利用前体物质定向选育阿维菌素高产菌株

以除虫链霉菌(Streptomyces avermitilis)AV-0105为出发菌株,采用紫外线诱变处理,并结合前体抗性定向选育阿维菌素高产菌株. 通过对致死率的考察,确定了紫外线诱变的最适剂量. 在分离培养基中分别加入不同体积分数的缬氨酸和D -脱氧葡萄糖作为前体物质进行正突变株的定向筛选,选育得到阿维菌素高产菌株 AV-03-35,其摇瓶发酵效价达到4 695 u/mL,较出发菌株提高15.5%. 采用该菌株在2 t罐进行生产验证,平均发酵效价达4 592 u/mL,较出发菌株提高了13%.     

藤黄灰链霉菌099生产麦拓莱霉素与脂肪酸酯的关系

为确定藤黄灰链霉菌099经聚酮途径合成麦拓莱霉素与初级代谢产物脂肪酸酯间的关系,利用柱层析,对发酵液中的脂肪酸酯加以分离纯化,用核磁共振谱、电喷雾电离质谱鉴定其结构,构建该菌株合理的代谢关系,并通过添加脂肪酸的发酵实验加以验证. 结果表明该菌株中不仅存在聚酮合成途径,而且存在脂肪酸酯代谢途径.     

植物病原菌拮抗放线菌的分离筛选与鉴定

从杭州地区采集的11份土样中共分离到99株放线菌.筛选出9株对产核黄素的无名假丝酵母Candida famata有拮抗作用.采用平板对峙法复筛到1株对供试的多种植物病原菌抑制效果较强的菌株W04,该菌株对西瓜枯萎病原菌的抑菌率达到79.1%;生长速率法测得其发酵滤液对西瓜枯萎病原菌的抑制率为82.6%.根据形态特征、生理生化特性及16S rDNA序列分析,鉴定该菌株为淡紫灰链霉菌Streptomyces lavendulae Waksman ＆ Curtis.     

利用组合抗药性突变选育秦岭霉素高产菌株

以秦岭链霉菌为出发菌株,采用链霉素和庆大霉素对其进行抗药性诱变.通过对致死率和活性最大提高率的测定,确定了链霉素和庆大霉素对出发菌株的最小抑制质量浓度(MIC),并在最小抑制质量浓度下筛选抗药性突变菌株.结合对诱变菌株的传代稳定性测定,获得了3株抗药性突变的高产菌株GS-4-04、GS-4-05和GS-4-06,其发酵液对5种细菌和4种病原真菌的抗菌活性比原始菌株显著提高.     

农用抗生素产生菌Streptomyce SN03菌株的诱变选育

以链霉菌SN03菌株为出发菌株,采用紫外线诱变结合微波诱变的处理方法,通过对致死率、正负突变率和活性最大提高率的测定,确定了紫外线和微波诱变的最适时间,结合对诱变菌株的传代稳定性测定,获得了高效菌株UV-1-W3,其发酵液的抑菌圈直径达到33.2mm,抗菌活性比出发菌株提高了30.20%。     

拮抗放线菌F-15的生防作用及其初步分类鉴定

从沈阳东陵区蔬菜大棚土壤中分离到1株拮抗放线菌,编号为F-15.采用平板对峙培养法和温室盆栽防治法测定了其抑菌活性,并通过形态学、化学的方法初步研究了其分类地位.结果表明:该菌株对供试的多种植物病原菌均有抑制作用,其中对瓜类枯萎病菌和番茄叶霉病菌抑制作用较强,平均抑菌带宽度达到14.8～15.0 mm.温室防病实验结果表明:其发酵上清液对番茄叶霉病具有良好的生防作用,防治效果可以达到73.2%.根据其菌株形态、培养特征、生理生化特性、细胞壁化学组分等分析,将菌株F-15归人链霉菌属,并初步鉴定为不吸水链霉菌的金色类群Streptomyces aureus.     

链霉素抗性诱变筛选阿维菌素高产菌株

以Y 0909-12为原始菌株,经过亚硝基胍诱变后,采用链霉素进行抗性筛选,得到一株高产菌株Y 0910-67,其效价较对照高出16.9%。     

微生物源黄酮类化合物的除草活性

菌株SPIR 94166是从广西采集的土壤样品中分离得到的具有产除草活性物质菌株，根据其形态学特征、生理生化特性和分子生物学特性等，认为菌株SPIR 94166是属于淡紫灰链霉菌。通过对菌种发酵液中除草活性物质的分离，得到3个活性组分，经NMR、红外、质谱等手段分析，这些除草活性物质分别鉴定为染料木素、黄烷酮以及槲皮素。     

Characterization of new class III lantibiotics--erythreapeptin, avermipeptin and griseopeptin from Saccharopolyspora erythraea, Streptomyces avermitilis and Streptomyces griseus demonstrates stepwise N-terminal leader processing

Lantibiotics are a large group of ribosomally synthesized peptides post-translationally modified to incorporate the amino acid lanthionine. They are classified, according to their biosynthetic pathway and bioactivity, into three major subtypes. Of Actinomycetes type III lantibiotics, only four peptides (SapB, SapT, LabA1, and LabA2) have been described and structurally characterized, although homologous gene clusters are abundant in other Actinomycetes. All these gene clusters share a similar architecture with a characteristic Ser/Ser/Cys motif in precursor peptides, which has previously been suggested to act as a precursor for lanthionine (SapB) and labionin (LabA2) rings. Mass spectrometry screening led to the discovery and characterization of three new representatives of type III lantibiotics: Avermipeptin (Avi), Erythreapeptin (Ery), and Griseopeptin (Gri) from Streptomyces avermitilis DSM 46492, Saccharopolyspora erythraea NRRL 2338, and Streptomyces griseus DSM 40236, respectively. Apart from the assignment of these peptides to their corresponding gene clusters, additional investigations on Avi, Ery and Gri peptides indicate stepwise leader processing by putative aminopeptidase-like protease(s), thus yielding mixtures of differently N-terminal-processed lantibiotic peptides. Similar peptide processing was observed for a heterologously expressed eryth biosynthetic gene cluster expressed in a Streptomyces host system. Remarkably, all isolates of the new type III lantibiotics contain both the amino acids lanthionine and labionin, thus implying dual-mode cyclase activity of the processing lyase-kinase-cyclase enzymes. These findings have implications for the structures and maturation of other type III lantibiotics from Actinomycetes.     

The butenolide signaling molecules SRB1 and SRB2 induce lankacidin and lankamycin production in Streptomyces rochei

New signaling molecules that induce lankacidin and lankamycin production in Streptomyces rochei were extracted from the culture filtrate and purified by Sephadex LH20 and silica gel chromatography with the help of bioassay. Chiral HPLC and ESI-MS analyses indicated the presence of two active components--SRB1 and SRB2--and their molecular formulas were established to be C15H24O5 and C16H26O5, respectively. By extensive NMR analysis, SRB1 and SRB2 were determined to be 2-(1'-hydroxy-6'-oxo-8'-methylnonyl)-3-methyl-4-hydroxybut-2-en-1,4-olide and 2-(1'-hydroxy-6'-oxo-8'-methyldecyl)-3-methyl-4-hydroxybut-2-en-1,4-olide, respectively. These structures were finally confirmed by chemical synthesis and the absolute configuration at C-1' was determined to be R in each case. The synthetic 1'R isomers induced production of lankacidin and lankamycin at around 40 nM concentrations. SRB1 and SRB2 are therefore distinct from the well-known 2,3-disubstituted γ-butyrolactone molecules such as A-factor, virginia butanolide, and SCB1 and and belong, like avenolide, recently isolated from Streptomyces avermitilis, to the γ-butenolide family.     

链霉菌菌株4903抑菌除草活性的研究

从士样中分离筛选的链霉菌4903菌株的代谢产物同时具有抑菌、除草活性。链霉菌4903对荔枝炭疽病菌（Glomerella cingulata）和荔枝霜疫霉菌（Peronophythora litchii）的抑菌圈透明,抑菌圈直径达到和超过25mm。除草活性生测结果表明：在固体培养条件下,链霉菌4903菌株对小麦（Triticum aestivum）和油菜（Brassica campestris）有强烈的抑制作用,链霉菌4903菌株对小麦苗的抑制率为94%.对油菜根和苗的抑制率分别为97％和83％。     

ARTP-DES复合诱变结合前体耐受性选育达托霉素高产菌株

为提高玫瑰孢链霉菌（Streptomyces roseosporus）AN-126的达托霉素（Daptomycin）产量，对菌株AN-126进行ARTP-DES复合诱变，并结合癸酸钠耐受性筛选，最终获得一株达托霉素高产菌株RR-447，摇瓶产量为101.41 mg/L，是出发菌株的2.44倍。传代实验表明，该菌株高产性能稳定遗传。对突变前后菌株的形态特征以及基因指纹图谱进行分析，结果显示突变菌株与出发菌株在形态学特征有明显差异，且高产菌株RR-447 基因组DNA在1.5 kb~2.0 kb之间存在一条特异性条带。通过在5L发酵罐中流加前体物质癸酸钠，菌株RR-447达托霉素产量达到521.39 mg/L。研究结果表明，ARTP-DES复合诱变结合癸酸钠耐受性是选育达托霉素高产菌株的一种有效育种手段，为达托霉素工业微生物育种以及其他菌株改良提供了技术参考。     

Pheromone-mediated copulatory responses of the screwworm fly,Cochliomyia hominivorax

A bioassay based on male copulatory responses occurring on contact with dead decoy insects was used to confirm the existence of a sex pheromone in the screwworm fly,Cochliomyia hominivorax. Males responded to female but not male decoys. Mated and virgin females were equally stimulatory. Activity was abolished when females were washed with hexane but partially restored by treatment with crude hexane extract of females. Responses decreased when extracts were diluted and when the number of females extracted per milliliter of hexane was decreased from 20 to 1 in the preparation of extracts concentrated to 0.4 female/l. Sexually mature female decoys of the 009 strain, the most laboratory-adapted of three strains examined in intrastrain tests, produced few copulatory attempts compared with those of Aricruz or DE-9 strains. However, newly emerged 009 as well as Aricruz females elicited responses from about 80% of sexually mature males. Those of the DE-9 strain stimulated fewer than 1%. The observation that 009 females were maximally stimulatory before becoming receptive to mating suggests that these strain differences resulted from laboratory colonization.