DNA cleavage by aromatic amines.

A series of aryl amines was found to induce cleavage of DNA. Subsequent refinement led to an efficient family of dimeric derivatives capable of cleavage at low concentration. Initial investigations suggest this is an unprecedented mode of DNA cleavage, which may be ultimately applied to the development of sequence-specific agents.     

Enzymology of cellulose degradation

In the last few years there has been a considerable improvement in the understanding of the mechanisms involved in the microbial degradation of cellulose, but there are still many uncertainties. As presently understood, it would appear that different mechanisms may operate in the various types of microorganism. Thus degradation of crystalline cellulose is effected by anaerobic bacteria by large Ca-dependent and thiol-dependent multicomponent endoglucanase-containing complexes (cellulosomes) located on concerted action of endo- and exo-glucanases which act some distance from the cell which renders cellulose soluble. All of the endo- and exo-glucanases possess a bifunctional domain structure: one contains the catalytic site, the other is involved in binding the enzyme to crystalline cellulose.     

Formation of trichothecenes by Fusarium solani var. coeruleum and Fusarium sambucinum in potatoes.

Fusarium solani var. coeruleum can form deoxynivalenol in potato tubers and in liquid medium, although concentrations observed in the rot were highly variable; acetyldeoxynivalenol and HT-2 toxin were detected in 1 to 3 tubers only (of 57). Trichothecenes were also detected in a very few (3 of 20) cultures of Fusarium sambucinum in potato tubers.     

Fungal Assciations: I. Synergistic Relation between Rhizoctonia solani Kuhn and Fusarium solani Snyder and Hansen in causing a Potato Tuber Rot

Rhizoctonia solani, Fusarium solani, and Phoma foveata werechosen for the study of disease caused by these fungi in differentcombinations in potato tubers. An initial Rhizoctonia infection,when followed by a Fusarium infection, gave an extensive rottingwith external pimple-like formations in some cases. This typeof rotting could not be brought about by individual infectionswith either of the two fungi, or jointly by them when Fusariumwas inoculated first. Microscopic observations of infected matureand young potato tubers showed that Rhizoctonia grew intracellularlywhen infected alone, whereas it grew inter- as well as intra-cellularlyin the successive double infection. Fusarium formed more haustorium-likestructures when inoculated alone that when it followed Rhizoctonia.The length of these structures in the double infection was greaterin mature than in young tubers. Atmospheric humidity affectedthe amount of rotting, the shape and colour of the rot, andthe morphology of the fungus in the tissue.     

Enzymatic degradation of nitriles by Klebsiella oxytoca

Klebsiella oxytoca, isolated from cyanide-containing wastewater, was able to utilize many nitriles as sole source of nitrogen. The major objective of this study was to explore the ability of K. oxytoca to utilize some nitriles and then further evaluate the pathways of transformation of cyanide compounds by K. oxytoca. Results from this study indicate that succinonitrile and valeronitrile were the most optimal sources of nitrogen for the growth of K. oxytoca. The biodegradation of acetonitrile proceeded with the formation of acetamide followed by acetic acid. The production of ammonia was also detected in this biodegradation experiment. Similar results were observed in the propionitrile biodegradation experiments. Collectively, this study suggests that the breakdown of acetonitrile or propionitrile by this bacterium was via a two-step enzymatic hydrolysis with amides as the intermediates and organic acids plus with ammonia as the end products.     

The Control of Fusarium solani f. sp. phaseoli by Fungicide Mixtures

Six fungicides were used either alone or in binary combination to control Fusarium solani f. sp. phaseoli. Of the three methods of application used, seed treatments and soil drenches were the best, although phytotoxicity was evident in some instances. Application as a seed soak for 1 h proved to be the worst method with most treatments showing signs of phytotoxicity. The results are discussed with reference to the use of fungicide mixtures to control foot rot of beans.     

Hydrolytic Activities of Fusarium solani and Fusarium solani f. sp. eumartii Associated with the Infection Process of Potato Tubers

The development of dry rot caused by Fusarium solani f. sp. eumartii was evaluated in susceptible (Huinkul) and resistant (Spunta) potato cultivars. Fungal proteolytic and polygalacturanase activities were measured at different days postinoculation either with the pathogenic F. solani f. sp. eumartii, isolate 3122 or with the non‐pathogenic F. solani, isolate 1042. After inoculation with the pathogenic fungus, proteolytic and polygalaturonase activities were higher in the susceptible than in the resistant cultivar. In addition, we found a correlation between the levels of proteolytic activity detected in the intercellular washing fluids with the size of the lesion area caused by F. solani f. sp. eumartii in Huinkul tubers. The action of the proteolytic activity over cell wall proteins of both potato cultivars was assayed. An extracellular potato protein with homology to proteinase inhibitors of the Kunitz family was identified as a substrate of the proteolytic activity in the susceptible cultivar. A microscopic study revealed differences between the potato genotypes in the rate of response to infection by F. solani f. sp. eumartii. In addition, the cell wall alteration caused by F. solani f. sp. eumartii in cortical cells of susceptible tubers was evaluated. The data with respect to the correlation between the course of cyto‐ and biochemical events of the two host–pathogen interactions were discussed.     

Addition of water to acyclic terpenoids by Fusarium solani

Summary Fusarium solani strains DSM 62416 and 62413 were found to hydrate trans-nerolidol or geranylacetone at the inner double bond. The stereochemical requirements for the substrate are rather narrow. Only E-configurated double bonds were accepted by the hydratases and no hydration was observed at the terminal isoprenyl unit of various substrates. The hydratases differ in their substrate specificity. While trans-nerolidol is accepted by the hydratase of strain DSM 62416 and geranylacetone is not, the contrary is found for the hydratase of strain DSM 62413. Higher yields of hydrated products under anaerobic conditions revealed that oxygen is not required as a cofactor.Dedicated to Professor Dr. Klaus Kieslich on the occasion of this 60th birthday     

14例茄病镰刀菌所致角膜溃疡临床分析

目的探讨真菌性角膜溃疡的病原学特点、临床表现及抗真菌综合治疗的方法。方法对2004年10月-2006年10月送检的疑似感染的角膜标本进行镜检、培养及菌种鉴定。对其中14例病历资料完整的茄病镰刀菌所致角膜溃疡患者进行临床分析。结果在33例送检标本中分离出茄病镰刀菌24株（72．7％）。上述14例患者中,有3例角膜穿孔合并眼内炎行眼球内容物除去术,3例行结膜瓣或羊膜移植,1例角膜移植,7例经非手术治疗保留较好视力。结论茄病镰刀菌是我国北方真菌性角膜炎的主要致病菌,可导致视力严重受损且治愈困难。早期诊断配合以抗真菌为主的综合治疗可阻止病情进展,明显改善视力。     

Soil factors influencing chlamydospore formation by Fusarium solani f. sp. phaseoli

Gel filtration and chromatographic separation of soil extracts gave three fractions which induced formation of chlamydospores by Fusarium solani f. sp. phaseoli. Depletion of nutrients had a similar effect.     

Root Rot of Trifolium subterraneum Induced by Fusarium solani

A fungus disease of Trifolium subterraneum, previously unknown in South Africa, was identified as Fusarium root rot caused by F. solani (Mart.) Sacc. Diseased plants were severely stunted. The characteristic internal root discolouration observed in the field, is described. The disease occurred mainly between Swellendam and Humansdorp in the southern and south-eastern Cape Province. The subterranean clover fields inspected were between 95 and 100 % infected with the root rot disease. T. repens and T. pratense were also susceptible.     

Mild hydrolysis of nitriles byFusarium solani strain O1

High levels of an aromatic nitrilase (about 37 microkat/L culture) were induced in Fusarium solani O1 after transfer of the mycelium from a rich medium into a medium with 20 mmol/L picolinonitrile. The mycelium was entrapped in lense-shaped particles consisting of a polyvinyl alcohol/polyethylene glycol copolymer (LentiKats). The cell-free extract was immobilized by hydrophobic binding onto a Butyl Sepharose column. The enzyme was useful for the mild hydrolysis of nicotinonitrile, isonicotinonitrile and benzonitrile.     

Pyrene degradation and copper and zinc uptake by Fusarium solani and Hypocrea lixii isolated from petrol station soil

Aims: This study aimed to isolate and identify potential polycyclic aromatic hydrocarbon (PAH)‐degrading and/or metal‐tolerant fungi from PAH‐contaminated and metal‐contaminated soils. Methods and Results: Pyrene‐degrading fungi were isolated from contaminated soil and tested for metal (Cu, Zn and Pb) compound solubilization and metal accumulation. Three strains of Fusarium solani and one of Hypocrea lixii were able to degrade more than 60% of initial supplied pyrene (100 mg l^?1) after 2 weeks. The isolates were grown on toxic metal (Cu, Pb and Zn)‐containing media: all isolates accumulated Cu in their mycelia to values ranging from c. 5·9 to 10·4 mmol per kg dry weight biomass. The isolates were also able to accumulate Zn (c. 3·7–7·2 mmol per kg dry weight biomass) from zinc phosphate‐amended media. None of the isolates accumulated Pb. Conclusions: These fungal isolates appear to show promise for use in bioremediation of pyrene or related xenobiotics and removal of copper and zinc from wastes contaminated singly or in combination with these substances. Significance and Impact of the Study: Microbial responses to mixed organic and inorganic pollution are seldom considered: this research highlights the abilities of certain fungal strains to interact with both xenobiotics and toxic metals and is relevant to other studies on natural attenuation and bioremediation of polluted sites.     

Removal of n-hexane by Fusarium solani with a gas-phase biofilter

A gas-phase biofilter inoculated with the fungus Fusarium solani, isolated from a consortium grown on hexane vapors, was used to degrade this compound. The biofilter, packed with perlite and operated with an empty bed residence time of 60 s, was supplied with hexane concentrations between 0.5 gm(-3) and 11 gm(-3). Biofilter performance was evaluated over 100 days of operation. Several strategies for supplying the nutritive mineral medium were assayed to maintain favorable conditions for the fungal growth and activity. The Fusarium system was able to sustain an average elimination capacity of 90 gm(-3)(reactor) h(-1) with a maximum of 130 gm(-3)(reactor) h(-1) . The mass transfer limitations due to high biomass development in the biofilter were confirmed in batch experiments. Bacterial contamination was observed, but experiments in the biofilter and in batch reactors using selective inhibitors and controlled pH confirmed the predominant role of the fungus. Results indicate that fungal biofilters can be an effective alternative to conventional abatement technologies for treating hydrophobic compounds.     

Removal of n-hexane by Fusarium solani with a gas-phase biofilter

A gas-phase biofilter inoculated with the fungus Fusarium solani, isolated from a consortium grown on hexane vapors, was used to degrade this compound. The biofilter, packed with perlite and operated with an empty bed residence time of 60 s, was supplied with hexane concentrations between 0.5 g m⁻³ and 11 g m⁻³. Biofilter performance was evaluated over 100 days of operation. Several strategies for supplying the nutritive mineral medium were assayed to maintain favorable conditions for the fungal growth and activity. The Fusarium system was able to sustain an average elimination capacity of 90 g m⁻³ _reactor h⁻¹ with a maximum of 130 g m⁻³ _reactor h⁻¹ . The mass transfer limitations due to high biomass development in the biofilter were confirmed in batch experiments. Bacterial contamination was observed, but experiments in the biofilter and in batch reactors using selective inhibitors and controlled pH confirmed the predominant role of the fungus. Results indicate that fungal biofilters can be an effective alternative to conventional abatement technologies for treating hydrophobic compounds.

     

茄病镰刀菌感染致角膜溃疡1例

报告1例由茄病镰刀菌感染引起的角膜溃疡。患者男性,40岁,木工,左眼红、痛、流泪、视力下降10 d。经过角膜清创,系统性及局部抗真菌治疗后好转。致病菌株经真菌学鉴定为茄病镰刀菌,它是真菌性角膜炎的常见致病菌之一。真菌性角膜炎病程进展迅速,能否及早诊治关系预后。真菌学检查是确诊的依据,临床应予重视。     

Degradation of Raspberry Suberin by Fusarium solani f. sp. Pisi and Armillaria mellea

When submers cultures of Fusarium solani f. sp. pisi and Armillaria mellea were grown in a medium supplemented with 0.5 % suberin isolated from raspberry periderm, hydrolytic enzymes were produced and measured by a spectrophotometric assay using p-nitrophenyl butyrate as substrate. The enzymatic activity in the culture fluids reached its peak after 32 to 44 days of incubation. In a gas-chromatographic assay of the enzymatic degradation of suberin, concentrated culture fluids of suberin-grown fungi were incubated with raspberry suberin. The culture fluids of F. solani and A. mellea catalyzed the release of chloroform-soluble products, which were analyzed by gas-liquid chromatography. Suberin monomers like fatty alcohols and acids with chain-lengths from C₁₆ to C₂₆ as well as C₁₆ and C₁₈ω-hy-droxyacids could be identified as products. The suberin-induced enzymes showed catalytic properties similar to cutin-hydrolyzing enzymes previously isolated from different fungi.