橄榄绿链霉菌木聚糖酶组对面包品质的改善

本文研究了橄榄绿链霉菌(Streptomyces olivaceovirdis)E-86产生的分子量约1200kDa木聚糖酶组对面包品质的影响。焙烤试验结果表明，添加20ppm木聚糖酶组的面包比容增加了38．8％，新鲜面包芯硬度降低了1／3，面包老化速率也明显减小。该木聚糖酶组具有内切酶和切枝酶的活性，在面粉中水溶性和水不溶性阿拉伯木聚糖组成比例范围内，对水不溶性阿拉伯木聚糖的降解作用比水溶性阿拉伯木聚糖快。因此，该酶组能够改善面包的品质。     

响应面法优化链霉菌HD-010 发酵产抗辣椒根腐病菌活性物质条件

用Plackett-Burman 和中心复合(central composite design)试验设计对影响拮抗链霉菌HD-010 菌株发酵生产抗辣椒根腐病菌活性物质的9 个因素进行筛选优化。结果表明：葡萄糖、蔗糖、玉米粉是发酵培养基中影响抗菌活性物质产量的主要因素。以发酵液效价值为响应值,对3 个因素进行中心复合设计,并经响应面法优化分析得到影响抗菌活性物质效价值的二阶模型,确定最优发酵培养基3 个关键因素的水平为：葡萄糖质量浓度10g/L,蔗糖质量浓度10.2g/L,玉米粉质量浓度25.8g/L,采用此优化配方,发酵液效价值比原始发酵培养基发酵液提高了55.28%,为进一步生产提供参考。     

产克拉维酸的棒状链霉菌突变株的选育

以棒状链霉菌(Streptomyces clavuligerus),B71为出发菌株,通过紫外线诱变育种,采用琼脂块法初筛和摇瓶发酵复筛,选育出2株甘油耐受性正向突变株S.clavuligerus B71—14和S.clavuligerus B71-49,在摇瓶条件下,其克拉维酸产量与出发菌株S.davuligerus B71相比,分别提高了90.6%和88.8%,并具有良好的遗传稳定性。     

微生物转化法生产香兰素

实验室保藏的一株链霉菌L1 93 6,能以阿魏酸和香兰素为唯一碳源生长 ,并能将阿魏酸转化为香兰素。研究中发现 ,阿魏酸是生产香兰素的较佳底物 ,添加量可达每升数克。发酵至 1 6h后添加阿魏酸 ,此时链霉菌L1 93 6对阿魏酸的转化能力最强。此株链霉菌不仅能耐受高浓度的香兰素 ,而且具有一种与其他菌株完全不同的代谢流。在转化阿魏酸时 ,当香草酸的积累量达到 2 0 0mg/L时 ,就开始积累香兰素作为代谢的主要过量合成产物。流加 2次底物阿魏酸使之浓度达 1 3g/L ,产物浓度达到 7 1 2g/L。相应的摩尔转化率为 69 9%。     

响应曲面设计法优化Streptomyces mediolani降解纤维素生成乙醇的培养基

选用梅久兰链霉菌（Streptomyces mediolani）K7-2进行培养,利用minitab15软件进行Plack-ett-Burman设计和响应曲面设计与回归分析,确定了影响乙醇生产的培养基成分中的3个主要效应因子是CMC-Na、尿素和pH,同时得到乙醇产量和各因素间的回归方程,通过计算,最终优化后的培养基成分是：CMC-Na10.3g/L,尿素0.2g/L、pH7.5、氯化铵10g/L、KH2PO42g/L、MgSO4·7H2O0.3g/L、CaCl20.3mg/L、（NH4）2SO41.4g/L、FeSO4·7H2O5mg/L、MnSO4.H2O1.56mg/L、ZnSO41.4mg/L、CoCl20.2mg/L。按照这个培养基成分培养菌株,发酵后得到的乙醇产量是0.3954g/L,乙醇产率是3.84%.     

1株具有高产木二糖的产木聚糖酶马特链霉菌的鉴定

对1株具有高产木二糖的产木聚糖酶马特链霉菌进行了鉴定。从土壤中新分离得到1株具有产木聚糖酶活性的链霉菌sp.67,对该菌株进行了形态特征、培养特征、生理生化特性及16S rDNA序列分析等方面的鉴定。PCR扩增得到其16s rDNA序列为1481 bp,通过在NCBI上BLAST比对,并运用ClustalX 1.8和MEGA 3.1软件绘制系统发育树,分析结果表明,sp.67与S.matensis AB 184221菌株同源性为99.52%。结合与生理生化实验结果一致,初步鉴定sp.67为马特链霉菌(Streptomyces matensis)。该菌株所产木聚糖酶水解碱处理棉籽饼的主要产物为木二糖,在生产高纯度木二糖中具有潜在的应用价值。     

金褐链霉菌SYAU0709中AURJ3M基因的克隆和序列分析

以金褐链霉菌SYAU0709的DNA为模板,根据GenBank中公布的PimM的序列设计引物,通过PCR扩增方法从金褐链霉菌中扩增出约579bp的目的片段。将PCR产物克隆至PMD19-T Vector中,通过PCR扩增及测序分析发现,金褐链霉菌SYAU0709来源的AURJ3M基因和纳塔尔链霉菌PimM基因的序列具有95%的相似性。通过摇瓶发酵显示AURJ3M基因能促进金褐霉素的生物合成。     

High yield antibiotic producing mutants of Streptomyces erythreus induced by low energy ion implantation

Conidia of Streptomyces erythreus, an industrial microbe, were implanted by nitrogen ions with energy of 40–60 keV and fluence from 1 × 10¹¹ to 5 × 10¹⁴ ions/cm². The logarithm value of survival fraction had good linear relationship with the logarithm value of fluence. Some mutants with a high yield of erythromycin were induced by ion implantation. The yield increment was correlated with the implantation fluence. Compared with the mutation results induced by ultraviolet rays, mutation effects of ion implantation were obvious having higher increasing erythromycin potency and wider mutation spectrum. The spores of Bacillus subtilis were implanted by arsenic ions with energy of 100 keV. The distribution of implanted ions was measured by Rutherford Backscattering Spectrometry (RBS) and calculated in theory. The mechanism of mutation induced by ion implantation was discussed.     

Biosynthesis of [14C]-11-De-O-Methyltomaymycin,a Precursor of Radiolabelled Antibody Drug Conjugates

Antibody drug conjugates (ADCs) are one of the most promising technologies to treat cancer as they combine the specificity of an antibody with the high potency of a cytotoxic molecule such as tomaymycin derivatives, which are DNA-interactive antitumor antibiotics previously isolated from bacterial broth. The multistep chemical synthesis of some tomaymycin derivatives is complicated because their structures contain a reactive imine bond. Therefore, we turned to biosynthesis to obtain ¹⁴C radiolabelled tomaymycin derivative to support ADME studies. Following Hurley's work (J. Antibiotics 1977 , 30, 349–370; Antimicrob. Agents Chemother. 1979 , 15, 42–45; Acc. Chem. Res. 1980 , 13, 263–269), the ¹⁴C radiolabel was incorporated efficiently in one step from radiolabelled tyrosine using the strain Streptomyces sp. FH6421. This process has been further optimized by using anthranilic acid as radiolabelled precursor, leading to one of the highest incorporation levels of radiochemical precursors published to date. This biosynthetic strategy is the fastest way to access such radiolabelled precursors.     

链霉菌DDE转座酶基因的克隆及生物信息学分析

从实验室保藏的菌株中筛选出一株产DDE转座酶的菌,经形态及生理生化、16S rDNA及建树分析比对,该菌株属链霉菌属灰褐类群,暂将其命名为Streptomyces labedae sp. X1。从Streptomyces labedae sp. X1基因组DNA扩增一401 bp的DDE转座酶基因,通过Blast和ISfinder数据库进行序列比对,结果显示其与ISAzo13家族转座酶的基因有88%的相似度。通过对其进行生物信息学分析,发现该基因可编码133个氨基酸,且该DDE转座酶的保守的氨基酸三联体分别位于Asp43、Asp49、Glu91上,理化性质结果显示编码产物为稳定的亲水蛋白;二级结构以α-螺旋和无规则卷曲为主,不存在信号肽和跨膜结构域,为非分泌蛋白;有14个磷酸化位点且仅有一个糖基化位点;高级结构以α-螺旋为主;通过SDS-聚丙烯酰胺凝胶电泳,结果显示在27 ku处出现条带。该研究结果为研究链霉菌DDE转座酶基因的表达机制提供了重要信息,对以后鉴定DDE转座酶活性以及它的结构和功能奠定基础。