The distribution of the NADPH regenerating mannitol cycle among fungal species

The mannitol cycle is an important NADPH regenerating system in Alternaria alternata. The cycle is built up of the following enzymes: mannitol 1-phosphate dehydrogenase, mannitol 1-phosphatase, mannitol dehydrogenase and hexokinase. The net reaction of one cycle turn is: NADH+NADP⁺+ATP NAD⁺+NADPH+ADP+P_i. The enzymes needed for an operating cycle were found in Aspergillus, Botrytis, Penicillium, Pyricularia, Trichothecium, Cladosporium and Thermomyces all genera belonging to Fungi Imperfecti. The only genus of this class lacking the cycle was Candida. No genera from the classes Basidiomycetes and Phycomycetes showed any mannitol 1-phosphate dehydrogenase or mannitol 1-phosphatase activities. The genera investigated, belonging to Ascomycetes, Gibberella, Ceratocystis and Neurospora all lacked mannitol 1-phosphate dehydrogenase. It was concluded that the mannitol cycle is an important and widespread pathway for NADH oxidation and NADP⁺ reduction in the organisms belonging to the class Fungi Imperfecti.     

Aflatoxin contamination caused by natural fungal infection of preharvest corn

Summary Aflatoxin contamination of developing corn (Zea mays L.) kernels caused by natural infection byAspergillus flavus Link ex Fries was studied in hybrids developed for the U.S. corn belt and for the southern U.S. and grown at diverse locations in 1977. Planting dates were staggered to examine the effect of crop maturity on infection by the toxin-producing fungus. A broad range of toxin values was observed at harvest; some levels exceeded the highest that had been previously recorded in corn. The highest concentration of aflatoxin B₁ detected was 8030 ppb. Levels of toxin differed significantly among planting dates in Florida and Georgia; the second planting date at these locations contained the highest toxin levels. Elevated concentrations of toxin were characteristic of kernel samples from southern locations and southeast Missouri; at these locations samples from hybrids developed for the south had significantly lower levels of toxin than hybrids developed for the corn belt. Ears with heavy insect damage had higher toxin levels than ears with less evidence of insect attack.Mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Volatile terpenoids from aeciospores of Cronartium fusiforme

Aeciospores of Cronartium fusiforme isolated from slash pine (Pinus elliottii) trees were analyzed for volatile terpenoids by GLC and GLC-MS. α-Pinene, β-pinene, Δ³-carene, myrcene, linonene, β-phellandrene, and δ-terpinene were the major monoterpenoid hydrocarbons present with only traces of camphene. A number of monoterpenoid alcohols were also present of which terpinen- 4-ol predominated. Among the various acyclic sesquiterpenes present, β-farnesene and β-citronellol were identified. Several aromatic compounds were also observed, including o-cresol.     

Phenylalanine ammonia lyase

The literature concerning the physiology and biochemistry of the enzyme phenylalanine ammonia lyase (PAL) (E.C. 4.1.1.5) from different organisms has been reviewed. Levels of the enzyme are affected by age, light, phytochrome, wounding, infection and growth modifiers. The possibility that PAL is involved in the control of phenolic metabolism has been critically examined.     

真菌B-39与虎杖悬浮细胞的共培养

初步探讨了虎杖来源真菌B-39与虎杖悬浮细胞之间的共培养关系及其白藜芦醇的积累特征。通过肉眼和光学显微镜观察真菌B-39与虎杖悬浮细胞的形态结构及生长情况,并用HPLC检测其白藜芦醇的积累特征,结果表明,两者均能在共培养体系中正常生长,且生长量可达4.908g,但白藜芦醇的含量下降了50μg/mL,而真菌接种量的大小可与虎杖悬浮细胞共培养建立一种动态平衡体系,由此推测真菌B-39与虎杖悬浮细胞可能为共生状态。     

墓室酥碱砖壁画及其环境的真菌多样性分析

【背景】酥碱是威胁古代墓室砖壁画保存的主要病害之一,水分和盐分共同作用下壁画产生酥碱病害,而其中真菌类群、来源及耐盐性鲜有报道。【目的】比较敦煌汉墓、晋墓和嘉峪关五号墓内砖壁画酥碱样品及其赋存环境空气中可培养真菌的群落组成、多样性及耐盐性,为砖壁画的防护提供理论依据。【方法】运用扫描电镜观察酥碱样品微观形貌,并结合能谱、X射线衍射进行成分分析;对样品培养、分离、纯化获得真菌纯菌株,运用形态和分子生物学技术鉴定种属;利用梯度含盐培养基研究菌株的耐盐性。【结果】墓室酥碱样品及环境空气中青霉属(Pencillium)、曲霉属(Aspergillus)和枝孢属(Cladosporium)丰度较高,为优势属;其他菌属包括镰孢菌属(Fusarium)和毛壳菌属(Chaetomium)为稀有属。三座墓室砖壁画酥碱中均存在烟曲霉(A.fumigatus)、花斑曲霉(A.versicolor)以及黄灰青霉(P.aurantiogriseum);酥碱样品与墓室内外空气中分离获得的真菌类群间有一定相似性。多数菌株可在含15%NaCl的培养基上生长,一株产黄青霉(P. chrysogenum)甚至可在30%盐浓度条件下生长。【结论】青霉属和曲霉属为墓室共有优势菌,多数菌株有较强的耐盐性。     

几种简便的木质素降解真菌定性筛选方法

简要介绍几种在前人基础上作了较大改进的木质素降解真菌的定性筛选方法,列出了每种方法的具体步骤并作了讨论。     

真菌异核体不亲和性机理研究进展

异核体不亲和性是普遍存在于真菌中的一种生物学现象,由特定的不亲和性位点所控制。从真菌异核体不亲和性分子机理的研究进展以及不亲和融合细胞死亡过程和相关蛋白的关系展开论述。对真菌异核体不亲和性机理的深入研究,将有助于揭示生物中非己识别系统的演化规律,并为解决原生质体融合子的不稳定性探索出有效的方法和途径。     

利用氯化苄提取适于分子生物学分析的真菌 DNA

随着生物技术的飞速发展,更加需要简便、快速地提取高质量的DNA。以往报导的提取真菌DNA的方法大都采用液氮研磨或酶解破坏细胞壁和膜的方式,从而导致繁琐、复杂和费时的提取过程。根据氯化苄在弱碱条件下与多糖上的羟基反应形成醚从而使多糖长链断裂的事实,我们发展了一种全新的真菌DNA提取方法,该方法使氯化苄在pH9.0时与细胞壁多糖作用,破坏细胞壁,基因组DNA因而得以从细胞中释放出来。新方法具有简便、快速、价廉的优点,得到的DNA蛋白质污染少、质量较高、产量稳定。对该法提取的DNA作进一步的分子生物学分析,如限制性内切酶酶解、RFLP分析、RAPD扩增,都取得了令人满意的结果。利用氯化苄提取真菌DNA的研究,迄今在国际、国内均尚未见报道。     

降解直链烷基苯磺酸钠真菌的分离鉴定及其降解特性

从直链烷基苯磺酸钠(LAS)污染土壤中分离到12株能降解LAS的真菌。经鉴定,它们分属于青霉属(Prnicillium)、曲霉属(Aspergillus)、帚霉属(Scopulariopsis)和头孢霉属(Cephalosporium)。研究了Aspergillus f-11降解LAS酶活诱导生成的条件及降解LAS的特点。还利用液相色谱对真菌和细菌降解LAS的产物进行了比较。