In planta production of indole-3-acetic acid by Colletotrichum gloeosporioides f. sp. aeschynomene

The plant pathogenic fungus Colletotrichum gloeosporioides f. sp. aeschynomene utilizes external tryptophan to produce indole-3-acetic acid (IAA) through the intermediate indole-3-acetamide (IAM). We studied the effects of tryptophan, IAA, and IAM on IAA biosynthesis in fungal axenic cultures and on in planta IAA production by the fungus. IAA biosynthesis was strictly dependent on external tryptophan and was enhanced by tryptophan and IAM. The fungus produced IAM and IAA in planta during the biotrophic and necrotrophic phases of infection. The amounts of IAA produced per fungal biomass were highest during the biotrophic phase. IAA production by this plant pathogen might be important during early stages of plant colonization.     

Bio-synthesis and applications of silver nanoparticles onto cotton fabrics

Recently, biosynthesis of metal nanoparticles has drawn considerable attention due to environment-ecofriendly and sustainable methods. Herein, fungus Fusarium solani was selected as candidate for biosynthesis of silver nanoparticles (AgNPs). Factors affecting the biomass concentration, pH of the reaction medium, AgNO(3) concentration and the ratio of AgNO(3) to biomass concentration on the production of AgNPs were extensively studied. Optimum conditions for biosynthesis of AgNPs could be attained using biomass of F. solani (10g/100ml); AgNO(3) (0.078g/100ml); pH, 12; temperature, 25°C and duration, 24h. Under these conditions, the maximum concentration of well stabilized AgNPs obtained was 2000ppm with a mean diameter range of 8-15nm. Such solution is unequivocally feasible for industrial applications. A diluted solution containing 50ppm AgNPs was applied to cotton fabrics which imparts antibacterial activity to the fabric with 97% and 91% reduction of Staphylococcus aureus and Escherichia coli, respectively.     

Kinetic and equilibrium studies on the biosorption of reactive black 5 dye by Aspergillus foetidus

An isolated fungus, Aspergillus foetidus had the ability to decolourize growth unsupportive medium containing 100 mg L(-1) of reactive black 5 (RB5) dye with >99% efficiency at acidic pH (2-3). Pre-treatment of fungal biomass by autoclaving or exposure to 0.1M sodium hydroxide facilitated more efficient uptake of dye as compared to untreated fungal biomass. Pre-equilibrium biosorption of RB5 dye onto fungus under different temperatures followed pseudo-second-order kinetic model with high degree of correlation coefficients (R(2)>0.99). Biosorption isotherm data fitted better into Freundlich model for lower concentrations of dye probably suggesting the heterogeneous nature of sorption process. Based on the Langmuir isotherm plots the maximum biosorption capacity (Q(0)) value was calculated to be 106 mg g(-1) at 50 degrees C for fungal biomass pre-treated with 0.1M NaOH. Thermodynamic studies revealed that the biosorption process was favourable, spontaneous and endothermic in nature. Recovery of both adsorbate (dye) and adsorbent (fungal biomass) was possible using sodium hydroxide. Recovered fungal biomass could be recycled number of times following desorption of dye using 0.1M NaOH. Fungal biomass pre-treated with NaOH was efficient in decolourizing solution containing mixture of dyes as well as composite raw industrial effluent generated from leather, pharmaceutical and dye manufacturing company.     

An enzyme-linked immunosorbent assay for monitoring of Aspergillus ochraceus growth in coffee powder, chilli powder and poultry feed

AIMS: The work was carried out to develop an immunoassay for estimation of Aspergillus ochraceus biomass on solid substrate. METHODS AND RESULTS: An indirect noncompetitive enzyme-linked immunosorbent assay (ELISA) was developed for determination of fungal biomass in food commodities using antibody raised against A. ochraceus mycelial antigen. The sensitivity of the assay was linear in the range of 10-160 microg fungal biomass per millilitre extract of coffee (R(2)=0.989), poultry feed (R(2)=0.987) and chilli (R(2)=0.989). The growth of A. ochraceus in the food commodities like chilli, coffee beans and poultry feed, under the influence of two levels of moisture (20% and 30%) were monitored by the ELISA. The maximum fungal colonization was observed in poultry feed (9.8 and 11.8 mg g(-1)) followed by coffee beans (6.8 and 11.3 mg g(-1)) and chilli (5.1 and 6.3 mg g(-1)) at 20% and 30% moisture after 20 days of incubation. Similarly the fungus produced maximum ochratoxin A in poultry feed (25 and 120 microg g(-1)) followed by coffee beans (8 and 24 microg g(-1)) and chilli (0.2 and 0.45 microg g(-1)) at 20% and 30% moisture after 20 days of incubation. CONCLUSIONS: The method can be used for quantitative estimation of fungal biomass and comparison of fungal colonization in food substrates varying in composition. SIGNIFICANCE AND IMPACT OF THE STUDY: The method can be adapted for studying the fungal colonization in different solid substrates under different culture condition. The method is sensitive to mould colonization of >or=0.02% (w/w) and can be used for early detection of specific fungal infestation in food commodities.     

Stimulation of astaxanthin formation in the yeast Xanthophyllomyces dendrorhous by the fungus Epicoccum nigrum

A fungal contaminant on an agar plate containing colonies of Xanthophyllomyces dendrorhous markedly increased carotenoid production by yeast colonies near to the fungal growth. Spent-culture filtrate from growth of the fungus in yeast-malt medium also stimulated carotenoid production by X. dendrorhous. Four X. dendrorhous strains including the wild-type UCD 67-385 (ATCC 24230), AF-1 (albino mutant, ATCC 96816), Yan-1 (beta-carotene mutant, ATCC 96815) and CAX (astaxanthin overproducer mutant) exposed to fungal concentrate extract enhanced astaxanthin up to approximately 40% per unit dry cell weight in the wild-type strain and in CAX. Interestingly, the fungal extract restored astaxanthin biosynthesis in non-astaxanthin-producing mutants previously isolated in our laboratory, including the albino and the beta-carotene mutant. The fungus was identified as Epicoccum nigrum by morphology of sporulating cultures, and the identity confirmed by genetic characterization including rDNA sequencing analysis of the large-subunit (LSU), the internal transcribed spacer, and the D1/D2 region of the LSU. These E. nigrum rDNA sequences were deposited in GenBank under accesssion numbers AF338443, AY093413 and AY093414. Systematic rDNA homology alignments were performed to identify fungi related to E. nigrum. Stimulation of carotenogenesis by E. nigrum and potentially other fungi could provide a novel method to enhance astaxanthin formation in industrial fermentations of X. dendrorhous and Phaffia rhodozyma.     

In Planta Production of Indole-3-Acetic Acid by Colletotrichum gloeosporioides f. sp. aeschynomene

The plant pathogenic fungus Colletotrichum gloeosporioides f. sp. aeschynomene utilizes external tryptophan to produce indole-3-acetic acid (IAA) through the intermediate indole-3-acetamide (IAM). We studied the effects of tryptophan, IAA, and IAM on IAA biosynthesis in fungal axenic cultures and on in planta IAA production by the fungus. IAA biosynthesis was strictly dependent on external tryptophan and was enhanced by tryptophan and IAM. The fungus produced IAM and IAA in planta during the biotrophic and necrotrophic phases of infection. The amounts of IAA produced per fungal biomass were highest during the biotrophic phase. IAA production by this plant pathogen might be important during early stages of plant colonization.     

Mycelium cultivation, chemical composition and antitumour activity of a Tolypocladium sp. fungus isolated from wild Cordyceps sinensis

AIMS: To examine and illustrate the morphological characteristics and growth kinetics of Cs-HK1, a Tolypocladium fungus, isolated from wild Cordyceps sinensis in solid and liquid cultures, and the major chemical constituents and antitumour effects of Cs-HK1 mycelium. METHODS AND RESULTS: The Cs-HK1 fungus was isolated from the fruiting body of a wild C. sinensis and identified as a Tolypocladium sp. fungus. It grew rapidly at 22-25 degrees C on a liquid medium containing glucose, yeast extract, peptone and major inorganic salts, with a specific growth rate of 1.1 day(-1), reaching a cell density of 23.0 g dw l(-1) in 7-9 days. Exopolysaccharides accumulated in the liquid culture to about 0.3 g l(-1) glucose equivalent. In comparison with natural C. sinensis, the fungal mycelium had similar contents of protein (11.7-microg) and carbohydrate (654.6-microg) but much higher contents of polysaccharide (244.2 mg vs 129.5 mg), adenosine (1116.8-microg vs 264.6 microg) and cordycepin (65.7 microg vs 20.8 microg) (per gram dry weight). Cyclosporin A, an antibiotic commonly produced by Tolypocladium sp., was also detected from the mycelium extract. The hot water extract of mycelium showed low cytotoxic effect on B16 melanoma cells in culture (about 25% inhibition) but significant antitumour effect in animal tests, causing 50% inhibition of B16 cell-induced tumour growth in mice. CONCLUSIONS: The Tolypocladium sp. fungus, Cs-HK1, can be easily cultivated by liquid fermentation. The mycelium biomass contained the major bioactive compounds of C. sinensis, and the mycelium extract had significant antitumour activity. SIGNIFICANCE AND IMPACT OF THE STUDY: The Cs-HK1 fungus may be a new and promising medicinal fungus and an effective and economical substitute of the wild C. sinensis for health care.     

Effect of phenolic monomers on biomass and hydrolytic enzyme activities of an anaerobic fungus isolated from wild nil gai (Baselophus tragocamelus)

AIMS: To test the anaerobic fungus, Piromyces sp. FNG5, for its tolerance to phenolic monomers released in the rumen by degradation of lignocellulosic poor-quality feeds. METHODS AND RESULTS: Effects of phenolic monomers on biomass and fibrolytic enzyme activities of a pure culture of lignocellulolytic anaerobic fungus (Piromyces sp. FNG5) isolated from faeces of wild nil gai (blue bull, Baselophus tragocamelus) were evaluated. There was a reduction in fungal biomass at 1 mm concentration of catechol with complete inhibition at 10 mm. p-Coumaric acid caused a reduction in biomass at 10 mm and no growth was observed above 20 mm concentration. The fungal isolate could tolerate up to 5 mm of ferulic acid without any reduction in biomass level, and was able to grow to some extent up to the highest level of ferulic acid tested (20 mm). Vanillic acid had no effect on biomass of the fungus even up to 50 mm level. The phenolic monomers varied in their potential to inhibit the secretion of carboxymethyl cellulase, xylanase, beta-glucosidase and acetyl esterase activities with catechol being the most inhibitory and vanillic acid being the least inhibitory. After 14 days of incubation, 38.49-65.14%p-Coumaric acid, 65.22-74.10% ferulic acid and 34.13-66.78% vanillic acid disappeared from the medium under anaerobic conditions. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY: It is concluded that the anaerobic fungus Piromyces sp. FNG5 is tolerant to phenolic monomers and has ability to degrade them. Therefore, such anaerobic fungi may play an important role in fibre degradation in the rumen.     

Effect of culture conditions on antifouling compound production of a sponge-associated fungus

Microorganisms associated with invertebrate hosts have long been suggested to be a source for bioactive metabolites. In this study, we reported that a sponge-associated fungus, Letendraea helminthicola, produced two antifouling compounds: 3-methyl-N-(2-phenylethyl) butanamide and cyclo(D-Pro-D-Phe). To optimize the production of these antifouling compounds, we then examined the production of compounds under different culture conditions (temperature, salinity, pH, and carbon and nitrogen sources). This fungus grew well and produced more compounds at temperatures between 18 and 30°C; the fungus grew well at 75 parts per thousand (ppt) salinity but produced the highest amount of antifouling compounds at 30 and 45 ppt. The optimal initial pH value for mycelial growth was 5.5 to 6.5, whereas the production of the antifouling compounds was maximized at pH 3.5 and 4.5. Glucose and xylose (as carbon sources) increased the production of antifouling compounds. Yeast extract and peptone (as nitrogen sources) maximized the production of mycelial biomass and antifouling compounds. Our results indicate that culture conditions greatly affect the production of bioactive compounds from mycelial fungal cultures as exemplified by strain L. helminthicola and that the conditions favorable for fungal growth may not be the best conditions for bioactive compound production.     

紫杉醇合成相关候选基因A02725的克隆及转基因菌株的构建

真菌紫杉醇合成相关基因的功能研究是揭示真菌紫杉醇合成机制的关键。为了揭示产紫杉醇内生真菌枝状枝孢霉MD2的候选基因A02725对宿主紫杉烷类合成的作用,本研究克隆了候选基因A02725的DNA全长序列(1 524 bp);生物信息学预测结果表明该基因编码蛋白为亲水蛋白,含508个氨基酸,无信号肽和跨膜结构,与牻牛儿基牻牛儿基焦磷酸合成酶(geranylgeranyl pyrophosphate synthase,GGPPS)具有79%的一致性;进一步构建该基因的超表达载体并转化枝状枝孢霉MD2,通过抗性筛选以及Southern blot检测,共获得27株转基因菌株,其中5株转基因菌株的外源基因是以单拷贝方式整合。该结果为深入分析超表达候选基因A02725对宿主紫杉烷类合成的影响奠定了基础。     

Biosynthesis of silver nanoparticles using aqueous extract from the compactin producing fungal strain

In the present study, an eco-friendly process for the synthesis of nanomaterials using a fungus, Penicillium brevicompactum WA 2315 has been attempted. The fungus has been previously utilized for compactin production. Supernatant of seed culture was used for the biosynthesis of silver nanoparticles. The aqueous silver ions were reduced to silver metal nanoparticles when treated with the fungal supernatant. After 72 h of treatment, silver nanoparticles obtained were in the range of 23–105 nm as obtained from TEM. The nanoparticles were characterized by UV, FTIR, SEM, TEM and XRD. The use of supernatant of the seed media of the said fungus opens up the exciting possibility of rational strategy of biosynthesis of nanomaterials.     

Interaction between a dark septate endophytic isolate from Dendrobium sp. and roots of D. nobile seedlings

Interactions between an isolate of dark septate endophytas (DSE) and roots of Dendroblum nobile Lindl.seedlings are reported in this paper.The isolate was obtained from orchid mycorrhizas on Dendrobium sp.in subtropical forest.The fungus formed typical orchid mycorrhiza in aseptic co-culture with D.nobile seedlings on modified Murashige-Skoog (MMS)medium.Anatomic observations of the infected roots showed that the DSE hyphae invaded the velamen layer,passed through passage cells in exodermis,entered the cortex cells,and then formed fungal pelotons of orchid mycorrhiza.D.nobile seedlings' plant height,stem diameter,new roots number and biomass were greatly enhanced by inoculating the fungus to seedlings.The fungus was identified as Leptodontidium by sequencing the polymerase chain reaction-amplified rDNA ITSt-5.8S-ITS2 (internal transcribed spacer (ITS)) regions and comparison with similar taxa.     

The effect of copper on the growth of wood-rotting fungi and a blue-stain fungus

The effect of copper (II) ions on the growth of three brown-rot fungi, six white-rot fungi and one blue-stain fungus in solid medium was evaluated. The fungi were grown in malt extract agar with different concentrations of copper added, and the radial growth rate was determined. At the end of the incubation period, the mycelial biomass and the media pH were determined. The white-rot and blue-stain fungus grew up to 3 mM and 6 mM copper, respectively and the brown-rot fungi were the only ones that grew up to 10 mM, with higher growth rates than those shown by the other fungi. In general, the brown-rot fungi produced greater acidification in the culture media than the white-rot fungi and blue-stain fungus, and the acidification increased when the amount of copper was increased. The biomass production for the different species, in the absence or presence of copper, was not related to the radial growth rate, and the fungal species that produced the greatest biomass amounts did not correspond to those that presented the highest growth rates. The brown-rot fungi Wolfiporia cocos and Laetiporus sulfureus and blue-stain fungus Ophiostoma sp. demonstrated greater tolerance to high copper concentrations in solid medium than the white-rot fungi, determined as radial growth rate. On the other hand, the highest biomass producers in solid medium with copper added were the white-rot fungi Ganoderma australe and Trametes versicolor and the brown-rot fungus Gloeophyllum trabeum.     

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.     

Contribution of fungal biomass to the diet of a freshwater isopod (Lirceus sp.)

SUMMARY. 1. The direct contribution of fungal biomass to the carbon needs of a freshwater isopod (Lirceus sp.) was measured using 14C-labelled fungi on leaf material. 14C-glucose was added to fungus-inoculated leaf discs periodically throughout the growth of the fungus. Amount of label incorporated into fungal biomass, radioactivity appearing in Lirceus after feeding on labeled fungus and the standing stock of fungus were used to calculate incorporation of fungal C by the consumer.
2. Incorporation rates ranged from 0.06 to 70 ng fungal C mg wet wt isopod-1h-1. These rates of incorporation represent from 0.05 to 57% of C respired by the isopod.
3. Fungal C does not meet the carbon needs of this consumer and the role of fungi as modifiers of the leaf substrate may be more significant than their role as a food source.     

Synthesis and antifungal activity of two novel spermidine analogues

Two spermidine analogues were synthesised and examined for antifungal activity. Both compounds used as 1 mM post-inoculation sprays reduced infection of barley seedlings by the powdery mildew fungus, Erysiphe graminis f.sp. hordei, infection of broad bean seedlings by the rust fungus, Uromyces viciae-fabae, and infection of apple seedlings by the powdery mildew fungus, Podosphaera leucotricha. Since these fungal pathogens cannot be cultured axenically, the effects of the two spermidine analogues on mycelial growth in vitro, as well as preliminary investigations on polyamine biosynthesis, were undertaken using the oat stripe pathogen, Pyrenophora avenae. Although neither compound affected radial growth of the fungus on plates, both analogues reduced fungal biomass in liquid culture substantially. The two spermidine analogues, used at a concentration of 1 mM, had no significant effect on the conversion of labelled ornithine into polyamines in P. avenae.     

Extra and Intracellular Synthesis of Nickel Oxide Nanoparticles Mediated by Dead Fungal Biomass

The use of dead biomass of the fungus Hypocrea lixii as a biological system is a new, effective and environmentally friendly bioprocess for the production and uptake of nickel oxide nanoparticles (NPs), which has become a promising field in nanobiotechnology. Dead biomass of the fungus was successfully used to convert nickel ions into nickel oxide NPs in aqueous solution. These NPs accumulated intracellularly and extracellularly on the cell wall surface through biosorption. The average size, morphology and location of the NPs were characterized by transmission electron microscopy, high-resolution transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The NPs were mainly spherical and extra and intracellular NPs had an average size of 3.8 nm and 1.25 nm, respectively. X-ray photoelectron spectroscopy analysis confirmed the formation of nickel oxide NPs. Infrared spectroscopy detected the presence of functional amide groups, which are probable involved in particle binding to the biomass. The production of the NPs by dead biomass was analyzed by determining physicochemical parameters and equilibrium concentrations. The present study opens new perspectives for the biosynthesis of nanomaterials, which could become a potential biosorbent for the removal of toxic metals from polluted sites.     

Mineralization of chlorpyrifos by co-culture of <Emphasis Type="Italic">Serratia</Emphasis> and <Emphasis Type="Italic">Trichosporon</Emphasis> spp.

A bacterial strain (Serratia sp.) that could transform chlorpyrifos to 3,5,6-trichloro-2-pyridinol (TCP) and a TCP-mineralizing fungal strain (Trichosporon sp.) were isolated from activated sludge by enrichment culture technique. The fungus could also degrade 50 mg chlorpyrifos l(-1) within 7 days. Co-cultures completely mineralized 50 mg chlorpyrifos l(-1) within 18 h at 30 degrees C and pH 8 using a total inocula of 0.15 g biomass l(-1).     

Fungal egg-parasites of plant-parasitic nematodes from Spanish soils

We have investigated the presence of fungal egg-parasites in Spanish soils with plant endoparasitic nematodes. Nine out of 68 samples (13%) yielded fungal parasites. The most common (seven strains) was Pochonia chlamydosporia var. chlamydosporia (= Verticillium chlamydosporium var. chlamydosporium), but Lecanicillium lecanii (= Verticillium lecanii) and Paecilomyces lilacinus were also found. Most strains were from cyst nematodes (Heterodera avenae or Heterodera schachtii). Biological factors related with the development and performance of these fungi as biocontrol agents were assessed in laboratory tetsts. Germination for most strains was around 90-100%. Higher biomass values were obtained, for most fungal strains, with complete or yeast extract peptone-glucose liquid media. P. lilacinus and L. lecanii showed the highest sporulation rates (1.0 x 10(9); and 1.5 x 10(10); conidia/g mycelium). All strains had optimum growth at 25 degrees C. High temperature (40 degrees C) was lethal to all fungi but low temperature (5 degrees C) allowed growth of L. lecanii. Most strains showed best growth close to pH 7. Several P. chlamydosporia strains produced diffusible pigments close to pH 3. Lack of moisture (aw = 0.887) in growth medium reduced but never arrested fungus growth. Proteolytic activity was, for all strains, the earliest and highest enzymatic activity. Amylolytic and pectinolytic activities showed the lowest values and the latter was undetectable for most strains. Pathogenicity (70-100percnt; egg infection) and severity (35-40 penetrating hyphae/egg) on Meloidogyne javanica were high for most strains tested. Our results show that agricultural soils in Spain contain fungal parasites susceptible to be biocontrol agents for plant-parasitic nematodes.