一株白僵菌的分离鉴定及对黄胸散白蚁的室内毒力测定

从罹病的玉米螟(Ostrinia furnacalis G)中分离纯化获得一株新菌株,命名为Bb-1。通过对该菌株的培养性状、形态特征观察,以及ITS基因序列分析,鉴定出Bb-1菌株为白僵菌属的球孢白僵菌(Beauveria bassiana)。用该菌株的5种浓度孢子液对黄胸散白蚁进行毒力试验。结果表明:用浓度为5×10~7孢子/mL的孢子液处理8d,黄胸散白蚁的校正死亡率达95.00%。5~8d的LC_(50)值为2.05×10~4~9.05×10~6孢子/mL。在5×10~3~5×10~7孢子/mL浓度下,菌株的LT_(50)值为4.28~8.59d。     

Combinatorial Mutasynthesis of Scrambled Beauvericins,Cyclooligomer Depsipeptide Cell Migration Inhibitors from Beauveria bassiana

Fungal cyclooligomer depsipeptides such as beauvericin, bassianolide, and enniatins display antibiotic, antifungal, insecticidal, broad‐spectrum cancer cell antiproliferative, and cell migration inhibitory activities. We have identified a gene encoding a novel enzyme, ketoisovalerate reductase (KIVR), which is the sole provider of D ‐hydroxyisovalerate (D ‐Hiv), a common precursor for cyclooligomer depsipeptide biosynthesis in Beauveria bassiana. KIVR and related hypothetical oxidoreductases encoded in fungal genomes are similar to ketopantoate reductases but not to D ‐hydroxycarboxylate dehydrogenases. We demonstrate that a KIVR knockout B. bassiana strain can be used for the efficient mutasynthesis of unnatural beauvericin congeners. Simultaneous feeding of precursor analogues enabled the combinatorial mutasynthesis of scrambled beauvericins, some assembled entirely from unnatural precursors. The effects of the introduced structural changes on the antiproliferative and cell migration inhibitory activities of these analogues were evaluated.     

球孢白僵菌Snf907发酵液对番茄根结线虫病的控病效果及防御酶活性影响

研究球孢白僵菌Snf907不同浓度发酵液对番茄幼苗期南方根结线虫病(Meloidogyne incognita)的室内防效,并测得处理后番茄幼苗根内几种主要寄主防御反应酶系PAL、POD、PPO、SOD和可溶性蛋白PRO活性的动态变化.结果表明:不同浓度的发酵液对根结和卵囊的抑制率均明显高于对照,其中原液和5倍稀释液达到80%以上.不同浓度发酵液处理后番茄幼苗根部的PAL、POD、PPO、SOD活性均高于对照,PRO活性显著增加.显示了球孢白僵菌在促进植物生长方面的潜能.     

球孢虫草(CCordycepa bassiana)活性威分分析

以球孢虫草为材料,采用气相色谱测定了虫草多糖的单糖组成,高碘酸钠比色法测定了D-甘露醇含量,应用HPLC测定了核苷类物质的含量及组成,并与野生冬虫夏草进行了比较.结果表明,球孢虫草胞外多糖(EPS)由甘露糖和半乳糖组成,摩尔比是1.2:1.0;胞内多糖(IPS)由甘露糖、半乳糖和葡萄糖组成,摩尔比为5.4:4.0:1.0.球孢虫草子座与发酵菌丝体中甘露醇的含量分别为4.01%和12.05%;且它们中均含有鸟苷、腺苷和尿苷三种成分,但发酵菌丝体中三者的含量高于子座及野生冬虫夏草.通过三种活性成分测定,为综合评价球孢虫草内在品质和开发球孢虫草提供了科学依据.     

不同湿度下球孢白僵菌对杨毒蛾的致病力

温度在25℃、空气相对湿度分别为(95±5)%、(85±5)%、(75±5)%、(65±5)%时,用球孢白僵菌感染杨毒蛾的2龄幼虫。试验表明,相对湿度越高白僵菌的致病力越高,杨毒蛾幼虫的死亡率也越高,各湿度下幼虫的LT50分别为6.799、8.325、10.672、12.597d。     

6种常用农药与球孢白僵菌和蜡蚧轮枝菌的相容性

测定了3种杀虫剂和3种杀菌剂在田间常规浓度下对球孢白僵菌和蜡蚧轮枝菌孢子萌发和菌丝生长的影响。供试杀虫剂对球孢白僵菌孢子萌发的影响很小,萌发率超过85％,对蜡蚧轮枝菌孢子萌发影响较大,抑制作用最小的吡虫啉,抑制率达到25％。3种杀菌剂几乎完全抑制了孢子的萌发。杀虫剂对球孢白僵菌的菌丝生长有一定抑制作用,抑制率为22．60％-38．39％;对蜡蚧轮枝菌菌丝生长的影响小于对球孢白僵菌的影响,抑制率为10．06％．17．61％。供试杀菌剂对球孢向僵菌和蜡蚧轮枝菌菌丝生长的抑制作用都较大,抑制率都在50％以上。     

4′-Methylflavanone Glycosides Obtained Using Biotransformation in the Entomopathogenic Filamentous Fungi Cultures as Potential Anticarcinogenic,Antimicrobial, and Hepatoprotective Agents

Flavonoid compounds exhibit numerous biological activities and significantly impact human health. The presence of methyl or glucosyl moieties attached to the flavonoid core remarkably modifies their physicochemical properties and improves intestinal absorption. Combined chemical and biotechnological methods can be applied to obtain such derivatives. In the presented study, 4′-methylflavanone was synthesized and biotransformed in the cultures of three strains of entomopathogenic filamentous fungi, i.e., Isaria fumosorosea KCH J2, Beauveria bassiana KCH J1.5, and Isaria farinosa KCH J2.1. The microbial transformation products in the culture of I. fumosorosea KCH J2, flavanone 4′-methylene-O-β-D-(4″-O-methyl)-glucopyranoside, 2-phenyl-(4′-hydroxymethyl)-4-hydroxychromane, and flavanone 4′-carboxylic acid were obtained. Biotransformation of 4′-methylflavanone in the culture of B. bassiana KCH J1.5 resulted in the formation of one main product, i.e., flavanone 4′-methylene-O-β-D-(4″-O-methyl)-glucopyranoside. In the case of I. farinosa KCH J2.6 as a biocatalyst, three products, i.e., flavanone 4′-methylene-O-β-D-(4″-O-methyl)-glucopyranoside, flavanone 4′-carboxylic acid, and 4′-hydroxymethylflavanone 4-O-β-D-(4″-O-methyl)-glucopyranoside were obtained. The Swiss-ADME online simulations confirmed the increase in water solubility of 4′-methylflavanone glycosides and analyses performed using the Way2Drug Pass Online prediction tool indicated that flavanone 4′-methylene-O-β-D-(4″-O-methyl)-glucopyranoside and 4′-hydroxymethylflavanone 4-O-β-D-(4″-O-methyl)-glucopyranoside, which had not been previously reported in the literature, are promising anticarcinogenic, antimicrobial, and hepatoprotective agents.     

球孢白僵菌几丁质酶基因chit1真核表达

采用PCR方法从球孢白僵菌的DNA中克隆出几丁质酶基因chit1,并将该序列构建到酿酒酵母(Saccharomyces cerevisiae)诱导型表达载体pYES2上,转化到酿酒酵母H158菌株中,通过Northern检验确定该基因在酿酒酵母中成功表达.经过酶活检测该转化子在培养48 h达到酶活高峰,达0.47 U/mL.     

A laboratory assessment of the potential of different strains of the entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae (Metschnikoff) to control Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) in stored cowpea

Twelve indigenous and exotic isolates of Beauveria bassiana and Metarhizium anisopliae were evaluated for their virulence and their ability to suppress populations of Callosobruchus maculatus in stored cowpea. LT₅₀ values ranged from 3.11 to 6.12 days following immersion in aqueous suspensions containing 1×10⁸ conidia ml⁻¹. Indigenous isolates that had been recovered from C. maculatus were more virulent in laboratory bioassays than exotic isolates from other insects. The two isolates with the shortest LT₅₀ values were compared in dose-response assays by immersion and by exposure to cowpea grains treated with dry conidia. In both assays B. bassiana 0362 was consistently more virulent than M. anisopliae 0351. By immersion, LC₅₀ values on day 6 post-treatment were 9.10×10⁴ and 7.10×10⁵ conidia ml⁻¹ for B. bassiana 0362 and M. anisopliae 0351, respectively. Exposure to treated grains gave LC₅₀ values of 1.15×10⁷ and 4.44×10⁷ conidia g⁻¹ grain for B. bassiana 0362 and M. anisopliae 0351, respectively. In 1 kg batches of cowpea stocked with 50 adult C. maculatus, B. bassiana 0362 at both 1×10⁷ and 1×10⁸ conidia g⁻¹ grain led to significant adult mortality and reduced F₁ emergence relative to untreated populations. At 1×10⁸ conidia g⁻¹ the effect of the fungus persisted into the F₁ generation. The net reproductive rates, R₀, measured 26 days after insects were released were 5.16 and 7.32 for the high and low doses compared to 9.52 for the untreated control.     

球孢白僵菌催化合成R-(+)-2-(4-羟基苯氧基)丙酸的菌种选育

[目的]为采用生物转化法合成R-(+)-2-(4-羟基苯氧基)丙酸(D-HPPA)提供优良菌株及理论基础。[方法]针对球孢白僵菌,先采用紫外(UV)诱变筛选高耐受R-(+)-2-苯氧基丙酸(D-PPA)的突变株,再使用等离子体(ARTP)诱变、N-甲基-N′-硝基-N-亚硝基胍(MNNG)诱变及ARTP和MNNG复合诱变提高突变株底物转化率。[结果]得到突变株UA1052,其底物转化率为98.5%、平均每天产物积累速率为6.93 g/(L·d)(较出发菌提高了796.6%),且遗传性稳定。[结论]ARTP诱变可大幅提高球孢白僵菌催化合成D-HPPA的能力。