1株链霉菌对几种植物病原真菌抑菌活性的初步研究

为了研究链霉菌1#所产生生物活性物质对5种植物病原真菌的抑菌活性。通过测定其次生代谢产物的抑菌活性,研究其发酵液对5种植物病原真菌的抑制效果。在链霉菌1#的同一批发酵液中,对小麦赤霉病菌的菌丝生长抑制率为60.8%,对棉花黄萎病菌和水稻稻瘟病菌的菌丝生长抑制率为20.0%和4.3%。100℃以下热处理15 min,拮抗成分仍有较强的活性,但随着温度和处理时间的增加,拮抗活性的丧失也就越明显。链霉菌1#粗发酵液活性作用在pH值3.8~9.0基本不变。在接近中性条件下,粗发酵液的拮抗活性最强。这株链霉菌的粗发酵液对几种植物病原真菌有很好的抑制效果,它具有一定的耐热性,抑菌效果在pH值3.8~9.0无明显差异。     

链霉菌702发酵液对水稻种传真菌的抑制效果、种子发芽率的影响

对江西省6个水稻主栽品种种传真菌进行了检测,研究了链霉菌702发酵液对水稻种传真菌的抑制效果及对种子发芽率的影响.结果表明,6个水稻主栽品种不同程度带有稻毛锥孢菌、镰刀菌等真菌,种子带菌率在52%以上.3种药剂处理和链霉菌702发酵液处理后均能有效抑制种传真菌,达到极显著水平,说明链霉菌702发酵液可以有效防治因种传真菌引起的幼苗病害.链霉菌702发酵液处理种子后,种子的发芽率受到一定影响,但没有达到显著水平,说明将链霉菌702发酵液用于水稻种子种传真菌防治的药剂是安全的.     

南昌链霉菌(Streptomyces nanchangensis)固体种子培养的研究

本研究进行了南昌链霉菌孢子培养基和培养条件的筛选。筛选到的培养基和培养条件,使南昌链霉菌每支斜面孢子达5亿多,是高氏培养基产孢量的7.5倍,培养时间缩短了7～10天。同时初步探讨了南昌链霉菌在固体培养基上孢子的消长变化及对摇瓶发酵产素的影响,发现该菌在固体培养基上能周期性地产生多代孢子;摇瓶发酵,接种第一代孢子南昌霉素 A 产量最多,接种第二代孢子则高效杀虫组分 B 的效价最高。     

丰加霉素对黄瓜立枯丝核菌的拮抗作用

采用菌丝生长速率法和盆栽试验法,研究了淀粉酶产色链霉菌Streptomyces diastatochromogenes胞外代谢产物丰加霉素（toyocamycin）对黄瓜立枯丝核菌Rhizoctonia solani的拮抗作用。结果表明：丰加霉素对立枯丝核菌菌丝生长和菌核形成有明显的抑制作用,抑制菌丝生长的EC50值为1.67mg.L-1,浓度为2.20mg.L-1时能完全抑制菌核形成。盆栽试验结果表明,丰加霉素对黄瓜苗立枯病有明显的保护和治疗作用。喷施19.54mg.L-1丰加霉素14d后,对黄瓜苗立枯病的治疗效果为71.91%,显著高于对照霉灵1000倍液的治疗效果（35.83%）;喷施19.54mg.L-1丰加霉素14d后,预防效果为51.06%,与对照无显著差异。施药后21d和14d的治疗效果和保护效果均相当;同时19.54mg.L-1和9.77mg.L-1的丰加霉素对黄瓜立枯病的作用效果相当。     

Temporal association of potato tuber development with susceptibility to common scab and Streptomyces scabiei‐induced responses in the potato periderm

Using hydroponics and novel non‐destructive pot culture systems which enable inoculation at specific tuber development stages, the dynamics of common scab infection patterns in potato were studied in order to provide more precise identification of tuber physiological factors associated with susceptibility. At the whole‐tuber level, infection percentages were greatest when Streptomyces scabiei inoculation occurred early; at 2 weeks after tuberization (WAT) 68% of tubers became infected, contrasting with late inoculation (8 WAT), when only 4% infection occurred. The first‐formed internodes were most susceptible to infection, whilst later‐forming and slower‐expanding internodes were less susceptible. Detailed tuber physiological examination of internode 2 showed that pathogen‐induced changes, including increased phellem (periderm) thickness, cell layers and phellem suberization (key physiological features believed critical to S. scabiei infection) were promoted through S. scabiei inoculation. Sequential harvesting showed enhanced phellem suberization (28% greater than the control) within 7 days of pathogen exposure, while phellem thickness and layer responses were also initiated early in the infection process (10–14 days after pathogen exposure) and these responses were independent of symptom expression. Differences in cultivar response were observed, with greater phellem suberization observed 10 days after tuberization (DAT) in the common‐scab‐tolerant cv. Russet Burbank than in the susceptible cv. Desiree. Likewise, Russet Burbank had thicker and more numerous cell layers in the phellem (up to eight cell layers) during early tuber growth (20–30 DAT) than Desiree (up to six cell layers).     

Cell-Associated Adsorption of Thorium or Uranium from Aqueous System Using Various Microorganisms

The cell-associated adsorption of thorium or uranium from the solution containing each metal only at pH 3.50 using various microorganisms was examined. Among the species tested, high thorium adsorption abilities were exhibited by strains of the gram-positive bacteria Arthrobacter nicotianae IAM12342, Bacillus megaterium IAM1166, B. Subtilis IAM1026, Micrococcus luteus IAM1056, Rhodococcus erythropolis IAM1399, and Streptomyces levoris HUT6156. And high uranium adsorption abilities were found in some gram-positive bacterial strains S. albus HUT6047, S. levoris HUT6156, and A. nicotianae IAM12342. Among these highly efficient thorium and uranium adsorbing microorganisms, S. levoris, which could adsorb the largest amount of uranium from the aqueous solution at pH 3.50, could adsorb about 383 mol thorium and 390 mol uranium per gram dry weight of microbial cells from the solution containing thorium or uranium at pH 3.50. The amount and time course of thorium adsorbed were almost unaffected by co-existing uranium; however, the adsorption of thorium was faster when carried out after the adsorption of uranium. Thorium adsorption also became faster when uranium was added after thorium adsorption. The effect of pH on thorium adsorption was also discussed.     

香兰素的生物转化研究

天然香兰素一直是香精香料行业关注的重点。本文介绍一株链霉菌L1936，它能以阿魏酸和香兰素为唯一碳源生长，且能将阿魏酸转化为香兰素。并发现阿魏酸是生产香兰素的一种非常好的底物，添加量可达12g／L。测试了链霉菌L1936对阿魏酸的转化能力，能够将6g／L阿魏酸转化为2．02g/L香兰素，相应的摩尔转化率为42．97％。而且此株链霉菌具有一种与其它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200mg／L时，就开始积累香兰素作为代谢的主要过量合成产物。流加两次底物阿魏酸后，产物浓度达到4．38g/L，相应的摩尔转化率为44．58％。     

Precise, simple screening for resistance in potato varieties to common scab using paper pots

Resistance to common scab pathogen Streptomyces turgidiscabies of seven potato varieties was compared in the field with a newly developed paper pot method. Seedlings raised in soil in paper pots containing inocula at 1 × 10³ to 10⁷cfu/g soil were transplanted into a scab-free field and grown for 3 months. The disease severity of the seven varieties in the field trials differed in iteration and from year to year, even though their resistance levels were approximately similar at the expected levels. With the paper pot method, the seven varieties had different resistance levels, which were almost completely consistent with the results of the field trials, at more than 1 × 10⁵cfu/g soil. Significant differences in disease severity between resistant and susceptible varieties were observed (P = 0.05) for 2 years, and the resistance level of the varieties was elucidated.     

拮抗球胞链霉菌AM6代谢产物防治烟草赤星病的田间效果测定

 拮抗球胞链霉菌AM6代谢产物田间试验结果表明,以含有AM6拮抗物质的液剂喷雾烟草叶片,可有效防治烟草赤星病。其防效随液剂中拮抗物质的含量的增加而升高,以100倍稀释防效最好,田间防效可达80.3%;施用次数2次为佳,平均防效达64.9%,病害发生严重时,可增施1次。同时,试验过程中发现含有AM6拮抗物质的液剂对烟草无明显药害。     

黄麻链霉菌NF0919菌株发酵培养基的优化

以黄麻链霉菌(Streptomyces corchorusii)NF0919菌株发酵液对草莓炭疽病菌(Glomerella cingulata)的抑菌率为效价指标。通过单因素试验筛选出NF0919菌株发酵用最佳的碳源、无机盐和氮源,在此基础之上,再通过正交试验和二次通用旋转组合设计试验,对NF0919菌株发酵培养基进行优化。结果表明:与发酵初始培养基相比,优化后得到的最佳培养基发酵液对草莓炭疽病菌的相对毒力效价提高了13.77倍。筛选得到的最佳发酵培养基组成为:10.2%马铃薯淀粉、2.6%棉籽蛋白、0.1%CaCO3、0.05%K2HPO4、0.05%MgSO4。