Effects of butylated hydroxyanisole,butylated hydroxytoluene and tertiary butylhydroquinone on growth and luteoskyrin production byPenicillium islandicum

Butylated hydroxyanisole (BHA), Butylated hydroxytoluene (BHT) and tertiary butylhydroquinone (TBHQ) alone in cultural media were tested for the inhibition of growth and luteoskyrin production by two toxigenic strains ofPenicillium islandicum UST-11 andP. islandicum HLT-6. In potato dextrose agar, the concentrations of BHA and TBHQ from 0.2 mg/disc, BHT from 5.0 mg/disc did affect the growth of both tested strains, but the initial concentrations of these antioxidants to reduced luteoskyrin production by UST-11 strain were BHA 0.5 mg/disc, BHT 1.0 mg/disc and TBHQ 0.4 mg/disc, while for HLT-6, BHA 0.4 mg/disc, BHT and TBHQ were 0.2 mg/disc, respectively. In grainy and powdery rice media, the effects of BHA, BHT and TBHQ on luteoskyrin production byP. islandicum UST-11 and HLT-6 were clearly demonstrated. The efficiency of the inhibitory effect was not only closely related to the concentration of antioxidants, but also completely inhibited the luteoskyrin production at a concentration of 200 mg/kg or higher. Also, the antioxidants at a concentration higher than 20 mg/kg reduced significantly the growth and luteoskyrin production by both strains ofP. islandicum.     

Inhibition of aflatoxin production by selected insecticides.

The insecticide naled completed inhibition production of aflatoxins B1, B2, G1, and G2 by and growth of Aspergillus parasiticus at a 100-ppm (100 microgram/ml) concentration. The insecticides dichlorvos, Landrin, pyrethrum, Sevin, malathion, and Diazinon significantly (P = 0.05) inhibited production of aflatoxins at a 100-ppm concentration. However, at a concentration of 10 ppm, significant inhibition in production of aflatoxins was found only with naled, dichlorvos, Sevin, Landrin, and pyrethrum. Dichlorvos, Landrin, Sevin, and naled inhibited growth of A. parasiticus by 28.9 , 18.9, 15.7, and 100%, respectively, at 100 ppm. Stimulation of growth was observed when diazinon was added to cultures. Aflatoxin B1 was most resistant to inhibition by insecticides, followed by G1, G2, and B2, respectively.     

Inhibition of aflatoxin production by selected insecticides

The insecticide naled completed inhibition production of aflatoxins B1, B2, G1, and G2 by and growth of Aspergillus parasiticus at a 100-ppm (100 microgram/ml) concentration. The insecticides dichlorvos, Landrin, pyrethrum, Sevin, malathion, and Diazinon significantly (P = 0.05) inhibited production of aflatoxins at a 100-ppm concentration. However, at a concentration of 10 ppm, significant inhibition in production of aflatoxins was found only with naled, dichlorvos, Sevin, Landrin, and pyrethrum. Dichlorvos, Landrin, Sevin, and naled inhibited growth of A. parasiticus by 28.9 , 18.9, 15.7, and 100%, respectively, at 100 ppm. Stimulation of growth was observed when diazinon was added to cultures. Aflatoxin B1 was most resistant to inhibition by insecticides, followed by G1, G2, and B2, respectively.     

Toxic Factors of Mould Origin

The chemistry and effects of mycotoxins associated with human and animal foodstuffs are reviewed. The aflatoxins, metabolites of Aspergillus flavus, have been implicated in fatal diseases of farm stock fed on infected peanut cake. Muscarine and the phalloidins are the causative agents in mushroom poisoning. Lysergic acid alkaloids are involved in ergotism. “Yellow rice” toxicity arises from infection with Penicillium islandicum, the active principles being islanditoxin and luteoskyrin. Various species of Penicillium, Aspergillus and Fusarium have been linked with other mycotoxicoses and their metabolites characterized. Several fungal metabolites are active hepatotoxins or carcinogens, and the possible etiological significance of mouldy foods is briefly considered, especially in relation to the high incidence of tropical liver disease. Better agricultural practices and more stringent testing to control and detect fungal contamination are advocated.     

Regulation of extracellular acid phosphatase biosynthesis by culture conditions in entomopathogenic fungusMetarhizium anisopliae strain CQMa102

Metarhizium anisopliae is an imperfect entomopathogenic fungus. Once invading into its host,M. anisopliae needs to absorb basic nutrients such as phosphorus from the host haemolymph. A large number of phosphorylated compounds in haemolymph cannot be directly utilised by the fungal cell and must be hydrolysed into available form by phosphatase before ingested. Aims of this paper were to investigate optimum fermentation conditions for production of acid phosphatase and phosphatase isoenzymes byMetarhizium anisopliae. The optimum fermentation conditions were: glucose, 20 g/l; (NH₄)₂SO₄, 2 g/l; casein, 4 g/l; MgSO₄, 0.5 g; KCl, 0.5 g; microelement salt solution, 10 ml; inoculum size, 1×10⁷ spores per 100 ml medium; initial medium pH, 6.0. Under these conditions, the highest total acid phosphatase activity was 3.05 U/ml in 4 days at 27 °C and 160 rpm. Synthesis of the acid phosphatase was repressed by 0.01% inorganic phosphate in culture medium. The spectrum of isoenzymes produced byM. anisopliae varied depending on the phosphorus source employed in the culture. A specific isoform with pI 9.45 was induced by casein, and another isoform of pI 8.21 was induced by phytic acid and disodium phenyl phosphate.     

Lipids of filamentous fungi as a material for producing biodiesel fuel

Species of various filamentous fungus taxa were tested for ability to produce lipids suitable as a material for manufacturing biodiesel. The mucoralean fungus Cunninghamella japonica was found to be a promising lipid producer. The inexpensive medium for its growth developed in this study contained ammonium nitrate as a nitrogen source. With its use, up to 16 g/l biomass and over 7 g/l lipids was obtained. The fungal lipids were dominated by oleic acid. It constituted 50% of total fatty acids. The iodine index of the lipid fraction was 86.61. The heat of combustion of the lipids, 37.13 MJ/kg, was close to the value for rapeseed oil.     

Parasitic and mutualistic associations between a mycorrhizal fungus and soybean: The effect of phosphorus on host plant-endophyte interactions

Soybean [ Glycine max (L.) Merr. cv. Kent] plants were colonized by the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus fasciculatum (Thaxt. sensu Gerd.) Gerd. and Trappe in pot cultures using an inert medium and a nutrient solution. Phosphorus was provided initially as 0, 25,50, 100 or 200 mg hydroxyapatite [HAP, Ca₁₀(PO₄)₆(OH)₂] per pot. Under the low (0 mg HAP) and high (100 and 200 mg HAP) P regimes, VAM plants showed 20, 25 and 38% growth retardation, respectively, relative to non-colonized controls. At 50 mg HAP, VAM plant growth was significantly enhanced (14%). Dry weight and P content of both VAM and control plants increased with increased P availability throughout the HAP gradient. Intraradical VAM fungal biomass increased linearly with increasing P availability. Extraradical VAM fungal biomass was smaller than the intraradical component of the fungus at the lowest and highest levels of P addition in the growth medium. The ratio of extra- to intraradical mycelium, a suggested index of VAM fungal effectiveness, was greatest for the 50 mg HAP treatment, coinciding with growth enhancement of the host plant. This enhanced growth of the host at an intermediate P level was apparently a result of increased P uptake by the endophyte.     

Decreased mineral availability enhances rock phosphate solubilization efficiency in <Emphasis Type="Italic">Aspergillus niger</Emphasis>

Microbial solubilization of rock phosphate (RP) is mainly achieved by the production of organic acids and medium acidification through H⁺ release. During RP solubilization, mineral nutrient availability is likely to be critical for determining how much carbon is channeled either for metabolite synthesis or for microbial growth, influencing organic acid release by microorganisms. Thus, the objective of this work was to study the relationships between the concentration of mineral nutrients in the growth medium and the efficiency of RP solubilization by Aspergillus niger FS1. For this, the fungus was grown in Czapek medium containing 0, 1, 2, 10, 50, and 100 % of its original concentration of mineral nutrients. Decreasing mineral availability in the growth medium led to decreases in fungal biomass and solubilized P, and increases in titratable acidity and solubilization efficiency as expressed by mg solubilized P per g fungal biomass (Y_P/B), indicating a shift in fungal metabolism from biomass production to organic acid release. The transfer of pre-grown biomass to media with or without added minerals confirmed that lower mineral availability increases Y_P/B and led to the solubilization of 76 % of P present in Patos RP. These observations open new perspectives on improving RP solubilization systems by manipulating mineral nutrient availability in the medium, with consequent gains in cost reduction.     

Biotechnological production of lactic acid integrated with fishmeal wastewater treatment by <Emphasis Type="Italic">Rhizopus oryzae</Emphasis>

Fishmeal wastewater, a seafood processing waste, was utilized for production of lactic acid and fungal biomass by Rhizopus oryzae AS 3.254 with the addition of sugars. The 30 g/l exogenous glucose in fishmeal wastewater was superior to starch in view of productivities of lactic acid and fungal biomass, and COD reduction. Fishmeal wastewater can be a replacement for peptone which was the most suitable nitrogen source for lactic acid production among the tested organic or inorganic nitrogen sources. Exogenous NaCl (12 g/l) completely inhibited the production of lactic acid and fungal growth. In the medium of COD 5,000 mg/l fishmeal wastewater with the addition of 30 g/l glucose, the maximum productivity of lactic acid was 0.723 g/l h corresponding to productivity of fungal biomass 0.0925 g/l h, COD reduction 84.9% and total nitrogen removal 50.3% at a fermentation time of 30 h.     

Physiological and genetic factors for process development of cyclosporine fermentations

Summary The new immunosuppressive agent cyclosporine (Cyclosporin A, Cy) is the most prominent member of a group of cyclic peptide fungal metabolites (cyclosporins) produced byTolypocladium inflatum in submerged fermentations. In the present study, kinetics and physiology of mycelial growth and Cy production byT. inflatum were examined. A new semi-synthetic medium was formulated, consisting of a single carbon/energy source, Bacto-peptone, potassium phosphate and potassium chloride. A wide variety of carbon sources supported growth and Cy production. 3% (w/v) sorbose gave the highest final Cy titer (105.5 mg/l), based on 10-day fermentations. The best specific Cy production was observed with 2% sorbose (14.3 mg Cy/g biomass) followed by 5%myo-inositol (13.4 mg Cy/g biomass). A feeding strategy consisting of sequential addition of two carbon sources such as sorbose and maltose was developed in order to reach higher volumetric production. Genetic studies were also conducted, focussing on the development of mutants for increased Cy production and for the synthesis of novel cyclosporins. In the course of these studies, viable protoplasts ofT. inflatum have been isolated and regenerated.     

雪腐格氏霉选择性培养基研究

以尿素作氮源,甘油作碳源,对雪腐格氏霉(Gerlachia nivalis)有较强的选择加富作用,Fe-Na-EDTA和生物素对其分生孢子萌发和菌落生长有促进作用,五氯硝基苯、敌克松、瑞毒霉是较好的选择抑制剂。据此,提出了雪腐格氏霉选择性培养基配方:KH_2PO_4 1.0g,MgSO_4·7H_2O 0.5g,Fe-Na-EDTA 0.01g,尿素0.5g,甘油2.0g,生物素0.005mg,五氯硝基苯20ppm,敌克松14PPm瑞毒霉5PPm,硫酸链霉素100单位/ml,氨苄青霉素50μg/ml,琼脂18g,蒸馏水1000ml。该培养基可促进雪腐格氏霉孢子萌发和菌落生长,可抑制多种常见土壤真菌生长。     

Studies on toxigenic fungi in roasted foodstuff (Salted seed) and halotolerant activity of emodin-producingAspergillus wentii

Commercial roasted salted peanuts (3% NaCl), popcorn (1% NaCl), summer-squash (9% NaCl), sunflower (3% NaCl) and wild-melon (3% NaCl) seeds are polluted with fungi, mostlyAspergillus flavus, A. niger, Penicillium chrysogenum, P. corylophilum andRhizopus stolonifer. Contamination of popcorn with the fungi is about 10 times higher than in the other foods. These fungi, common also on unsalted seeds, are significantly inhibited in seeds (30% moisture content) treated with 9–21% NaCl. The halotolerantA. wentii represents the main fungus recovered from seeds treated by 15–21% NaCl. 9% NaCl stimulated emodin production byA. wentii on peanut and citrinin production byP. chrysogenum on popcorn and sunflower. Aflatoxin, citrinin and emodin production on popcorn persisted up to 15% NaCl. Popcorn is thus strongly susceptible to fungal invasion and toxin pollution. The halotolerance ofA. wentii was confirmed by its strong permanent growth in liquid medium at up to 15% NaCl. At 3% NaCl the mycelial growth and nitrogen content increased while the level of emodin and lipid production decreased. CO₂ evolution strongly increased at 9–15% NaCl as a characteristic ofA. wentii salt tolerance. Emodin inhibited seed viability and the inhibition dose for 50% reduction (LD₅₀) was 65 mg/L for popcorn and 45 mg/L for sunflower.     

Production of alternarioi and alternariol monomethyl ether in natural substrates in comparison with semisynthetic culture medium

The comparison In toxins production and growth byAlternarla strains in liquid, solid culture media and natural substrates (rice and sunflower) was evaluated. Ground rice- corn steep liquor medium (GRCS) was the more suitable medium for production of alternariol (AOH) and alternariol monomethyl ether(AME). The maximum levels produced were 676 μg/50ml AOH and 1570/50ml AME. Rice was better than sunflower In supporting toxins production. Different ratios AOH/AME were found according to the substrate evaluated.     

Induced Resistance to Pathogenic Fungi in Norway Spruce

Norway spruce (Picea abies) trees (approximately 16 m high) of a single clone were used to study the effects of fungal infection and wounding on induction of resistance to the bark beetle-associated bluestain fungus Ceratocystis polonica. A dose-response experiment was designed involving three different dosages of fungal (fungus and wound) and sterile agar (wound) pretreatment inoculations (10, 50, or 100 inoculations/m² on the stem between 0.8 and 2.0 m high). Three weeks after pretreatment, trees were challenged with a massive C. polonica inoculation (400 inoculations/m²). Control trees that received no pretreatment were heavily colonized and killed by the challenge inoculation. The high and medium fungal pretreatments reduced subsequent fungal colonization success by 76% to 97% relative to the control, and fungal pretreatments protected the trees much more efficiently than sterile agar pretreatments. The protection was demonstrated to be local and not systemic in a subsequent experiment, where trees were pretreated with the medium fungal dosage on the lower bole and challenge inoculated further up the stem. Protection was also demonstrated to be pathogen nonspecific, as trees that had been pretreated with a medium dosage of the root rot fungus Heterobasidion annosum showed enhanced resistance to challenge inoculation with C. polonica.     

Stimulation of Tentoxin Synthesis by Aged-Culture Filtrates and Continued Synthesis in the Presence of Protein Inhibitors

Tentoxin, a cyclic tetrapeptide produced by Alternaria alternata (Fries) Keissler, induces chlorosis in certain seedling plants. It can be extracted from culture filtrates of the fungus. Tentoxin production is stimulated and increased by using a mixture of aged culture filtrates and modified Richards solution. Aged culture filtrates can be obtained from 3-week-old or older cultures of A. alternata in modified Richards solution or Pratts solution. A mixture of aged culture filtrate and fresh medium in the ratio 2:3 gives the maximal enhancement of tentoxin production. This growth system provided us with a model for studying the effects of protein synthesis inhibitors on tentoxin production. Two antibiotics which inhibit protein synthesis at the ribosomal level were tested on growth, protein synthesis, and tentoxin production in A. alternata cultures. Cycloheximide at concentrations of 500 μg/ml or emetine at concentrations of 250 μg/ml did not inhibit tentoxin synthesis, although they stopped mycelial growth and protein synthesis of the fungus at the logarithmic growth stage in the enhancement medium. These results led us to conclude that tentoxin, like certain other bioactive cyclic peptides, is synthesized by a nonribosomal peptide synthesis mechanism.     

Benomyl: A broad spectrum fungicide for use in plant cell and protoplast culture

The systemic fungicide methyl-1-(butylcarbamoyl)-2-benzimidazole carbamate (benomyl), is a broad spectrum fungicide. Benomyl at concentrations up to 50 mg/l does not inhibit the growth of suspension cultures ofNicotiana tabacum, Datura innoxia, Daucus carota, Glycine canescens, andSolanum tuberosum nor growth ofN. tabacum orN. plumbaginifolia protoplasts if benomyl is dissolved by autoclaving or boiling. Addition of benomyl dissolved in dimethyl sulfoxide results in a visible toxicity. Benomyl, at 6.25–50 mg/l preventsPenicillium spp. growth in both protoplast and cell cultures and can be used to remove fungal contaminates after one to three transfers without visibly retarding plant cell growth. Due to the broad spectrum of fungicidal activity, and nontoxicity at high concentrations when dissolved by boiling or autoclaving, benomyl can be used effectively to control or prevent fungal contamination in plant cell and protoplast cultures.     

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.     

Persistence and Viability of Lecanicillium lecanii in Chinese Agricultural Soil

The entomopathogenic fungus L. lecanii has been developed as biopesticides and used widely for biological control of several insects in agricultural practice. Due to the lack of isolation/count methods for L. lecanii in soil, the persistence of this fungus in soil appears to have attracted no attention. A selective medium and count method for L. lecanii in soil based on cetyl trimethyl ammonium bromide (CTAB) was developed, and then the persistence and viability of this fungus in soil were investigated under field conditions between 2012 and 2014. The results showed that the rate of recovery for L. lecanii in soil on the selective CTAB medium was satisfactory. The minimum CFUs for L. lecanii on the selective medium (0.5 g/L CTAB) was about 10² conidia/g soil. The L. lecanii density in soil declined quickly in the first month after inoculation with fungal conidia, kept stable for 6 to 10 months, and then decreased gradually until undetectable. L. lecanii could persist for at least 14 months in the agricultural soil of northern China. The colony growth, conidia yield and germination rate on plates, as well as the median lethal concentration or times (LC₅₀ or LT₅₀) to aphids, mycelium growth in aphids and sporulation on aphids of L. lecanii did not change significantly during the persistence in soil. In general, the count method developed here was a very useful tool for monitoring the dynamics of natural or introduced L. lecanii populations in soil, and the data on the persistence of L. lecanii in soil reported here were helpful for biological control and environmental risk assessment.