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PubMedDate not supplied

Removal of herbicides from liquid media by fungi isolated from a contaminated soil.

Fungi were isolated from soil samples corresponding to pesticide-contaminated soil (CS) and noncontaminated soil (NCS) in the Annaba vicinity (Algeria) and identified. The number of isolates obtained from CS and NCS were 263 and 288, respectively. The most frequent species (Aspergillus fumigatus, A. niger, A. terreus, Absidia corymbifera, and Rhizopus microsporus var microsporus) were not sensitive to the pesticides. The growth of the genus Trichoderma was inhibited by the pesticides, while genera Absidia and Fusarium were stimulated. The 53 species isolated were assayed for their ability to remove metribuzin from liquid medium. Only Botrytis cinerea from NCS and Sordaria superba and Absidia fusca from CS removed more than 50% of the compound after 5 d. Metamitron was very resistant. Among the 21 species tested, only Alternaria solani (from NCS), Drechslera australiensis (from CS and NCS), and Absidia fusca (from CS) reduced the concentration in the medium more than 10% (10-16%). Twelve species were grown with linuron, seven of them were inefficient in removing this compound. The two strains of Sordaria macrospora yielded 22 to 25% depletion, while Botrytis cinerea depleted linuron almost completely. Among the 31 species assayed for their ability to eliminate metobromuron, Botrytis cinerea (from CS and NCS) depleted almost completely the chemical from the medium. Rhizopus oryzae and Absidia fusca from CS removed 40 and 47% of the compound, respectively. No systematic relationships were observed between the soil contamination and herbicide elimination capacities of soil fungi. Absidia fusca and Botrytis cinerea were particularly interesting for bioremediation purposes because they were able to transform efficiently three of the four compounds assayed.

Biodegradation, Environmental↗
PubMed2003

Plants, mycorrhizal fungi and endobacteria: a dialog among cells and genomes.

This review focuses on mycorrhizas, which are associations between fungi and the roots of 90% of terrestrial plants. These are the most common symbioses in the world; they involve about 6000 species of fungi distributed through all the fungal phyla and about 240000 species of plants, including forest and crop plants. Thanks to mycorrhizal symbiosis and nutrient exchanges, regulated by complex molecular signals, the plant improves its vegetative growth, while the fungus accomplishes its life cycle. Molecular and cellular analyses demonstrate that during colonization the cellular organization of the two eukaryotes is completely remodeled. For example, in cortical cells, structural modifications involve both the host and the microbiont. Recent studies revealed that in arbuscular mycorrhizas (AM), system complexity is increased by the presence of a third symbiont: a bacterium living inside the fungus. The presence of this resident genome makes the investigation of the molecular dialogues among the symbiotic partners even more complex. Molecular analysis showed that the bacterium has genes involved in the acquisition of mineral nutrients. The experimental data support the current view that mycorrhizal symbioses are often tripartite associations.

Bacterial Physiological Phenomena↗
PubMed2001

Pathogenicity of four strains of entomopathogenic fungi against the bovine tick Boophilus microplus.

OBJECTIVE: To evaluate the pathogenicity of 4 strains of the entomopathogenic fungi Metarhizium flavoviride var flavoviride and Metarhizium anisopliae var anisopliae in vitro against the bovine tick Boophilus microplus. SAMPLE POPULATION: 300 B. microplus females were used for each series of 5 conidial suspensions of the 4 fungal strains; a control group of 60 females was treated with sterilized water. PROCEDURE: For each fungal strain, sporulating cultures were used to produce conidial suspensions containing 10(4), 10(5), 10(6), 10(7), and 10(8) conidia/ml. A bioassay was performed by immersing B. microplus females in conidial suspensions; the procedure was repeated with a new group of 60 females for each dilution (a total of 300). A control group was immersed in the same volume of sterilized distilled water. Ticks were maintained at 27 C and 80% relative humidity for 7 days, and the following variables were evaluated: weight before egging, egging weight, percentage eclosion, reproductive efficiency, and percentage control. RESULTS: A low index of eclosion was found in the treated groups, with a progressive decrease in percentage eclosion (control = 100%) with increased conidial concentration. The highest level of effectiveness of biocontrol was detected in groups treated with concentrations of 10(7) and 10(8) conidia/ml. CONCLUSIONS AND CLINICAL RELEVANCE: Strains of the entomopathogenic fungi M. anisopliae var anisopliae and M. flavoviride var flavoviride were effective as biological control agents against B. microplus, with M. flavoviride strain CG-291 being the most effective. The pathogenicity of these strains and the development of an application method for this fungus for control of ticks may result in improved animal productivity and a reduction in environmental pollution through the use of fewer chemical insecticides.

Animals↗
PubMed1986

Biotransformation of polycyclic aromatic compounds by fungi.

Incubations of several polycyclic aromatic hydrocarbons (PAHs) and heteroaromatic compounds with a series of common micro-organisms have been performed. The PAHs were not metabolized by any of the fungi studied. The sulphur-containing heterocyclic aromatic compounds dibenzothiophene, thioxanthone and thiochromanone were oxidized at sulphur by C. elegans. Other fungi are capable of oxidation at the sulphur atom of dibenzothiophene and thioxanthone. C-1 and C-3 methyl substituted thioxanthones are hydroxylated at the methyl group by C. elegans.

Biotransformation↗
PubMed1989

Conversion of pentoses to ethanol by yeasts and fungi.

Fermentation of D-xylose is of interest in enhancing the yield of ethanol obtainable from lignocellulosic hydrolysates. Such hydrolysates can contain both pentoses and hexoses, and while technology to convert hexoses to ethanol is well established, the fermentation of pentoses had been problematical. To overcome the difficulty, yeasts and fungi have been sought and identified in recent years that can convert D-xylose into ethanol. However, operation of their cultures in the presence of the pentose to obtain rapid and efficient ethanol production is somewhat more complex than in the archetype alcoholic fermentation, Saccharomyces cerevisiae on D-glucose. The complexity stems, in part, from the association of ethanol accumulation in cultures where D-xylose is the sole carbon source with conditions that limit growth, by oxygen in particular, although limitation by other nutrients might also be implicated. Aspects of screening for appropriate organisms and of the parameters that play a role in determining culture variables, especially those associated with ethanol productivity, are reviewed. Performance with D-xylose as sole carbon source, in sugar mixtures, and in lignocellulosic hydrolysates is discussed. A model that involves biochemical considerations of D-xylose metabolism is presented that rationalizes the effects of oxygen on cultures where D-xylose is the sole carbon source, notably effects of the specific rate of oxygen use on the rate and extent of ethanol accumulation. Alternate methods to direct fermentation of D-xylose have been developed that depend on its prior isomerization to D-xylose, followed by fermentation of the pentulose by certain yeasts and fungi. Factors involved in the biochemistry, use, and performance of these methods, which with some organisms involves sensitivity to oxygen, are reviewed.

Biotechnology↗
PubMed1995

Production of polyclonal and monoclonal antibodies against hyphae from arbuscular mycorrhizal fungi.

Polyclonal and monoclonal antibodies were produced against hyphae of the arbuscular mycorrhizal fungus Glomus monosporum. The polyclonal antibodies (pAbs) were raised in a rabbit by immunizing with hyphae. They were tested for their specificity by a dot-immunoblot assay (DIBA). After the third immunization, a distinct difference in the signal strength was observed between the antisera and the preimmune serum. The pAbs showed cross-reactions to a number of fungal species, both mycorrhizal and other. For the production of monoclonal antibodies (mAbs), mice were immunized intraperitoneally with hyphae. The resulting hybridoma cell culture supernatants were tested by an indirect immunolabeling procedure. For this purpose the hyphae were immobilized on silane-coated microscopic slides. The mAb 8A7 reacted with hyphae from all Glomus isolates tested so far. Cross-reactivities were not observed with hyphae from fungi of the family Acaulosporaceae, phytopathogenic fungi tested so far, or from spores from Glomus species.

Animals↗
PubMed1984

Lipid metabolism in fungi.

So far, reviews that have appeared on fungal lipids present data mainly on the lipid composition of these organisms and the influence of lipids on their physiology. These reviews provide little information about the enzymes of lipid metabolism in these organisms and it is assumed, by most workers, that lipid synthesis in all fungi takes place as in Saccharomyces cervesiae, the only fungus in which the complete pathways of phospholipid biosynthesis have been worked out. During the last few years, literature has accumulated on lipid metabolic enzymes of other fungi, as investigators became increasingly interested in this area of research. The present review, after an introduction, will be divided into different sections and each section will deal, comparatively, with various aspects of fungal lipid metabolism and physiology. This review will, therefore, bring out the differences or similarities of lipid metabolism in diverse fungal species.

Acetyl-CoA Carboxylase↗
PubMed1986

Parasitic adaptation of pathogenic fungi to mammalian hosts.

Pathogenic fungi involved in medical and veterinary mycology can be classified in three different groups according to their level of adaptation to parasitism. Only a few species belonging to dermatophytes can be considered genuine parasites as opposed to molds or fungi involved in systemic mycoses. Ecological, ethological, biochemical, and immunological factors can play a role in preadaptation or adaptation to parasitic life and are discussed.

Adaptation, Physiological↗
PubMed1987

The genetics of medically important fungi.

The present review is concerned with recent progress in basic genetic investigations with a variety of fungi which are pathogenic for man and animals. The principles and strategies involved in undertaking genetic investigations of sexual species and of asexual species are discussed. Progress in genetic analysis of Cryptococcus neoformans made possible by the discovery of its sexual phase is described in detail, as is progress in development of parasexual methods of analysis in Candida albicans. The genetic bases of virulence and drug resistance are discussed for those few species in which these phenotypes have been investigated. Suggestions for future research, including the application of recent advances in molecular biology to the study of pathogenic fungi, are presented.

Alleles↗
PubMed1998

Extracellular phospholipases as universal virulence factor in pathogenic fungi.

Microbial pathogens use a number of genetic strategies to invade the host and cause infection. These common themes are found throughout microbial virulence factors. Secretion of enzymes, such as phospholipase, has been proposed as one of these themes which is used by bacteria, parasite, and pathogenic fungi. The role of extracellular phospholipase as a potential virulence factor in pathogenic fungi, including Candida albicans, Cryptococcus neoformans and Aspergillus has gained credence recently. In this address data implicating phospholipase as a virulence factor in Cryptococcus neoformans and Aspergillus fumigatus will be presented. This will be followed by a more detailed description of our molecular and biochemical approaches we used to more definitively delineate the role of phospholipase in the virulence of C. albicans. First, we purified the phospholipase B protein, the dominant phospholipase secreted by C. albicans, obtained the amino acid sequence of its N-terminus and an internal peptide fragment, and used this information to clone the gene encoding the protein using a PCR-based approach. Nucleotide sequence analysis revealed an ORF of 1818 bp that predicted for a pre-protein of 605 amino acid residues. The deduced amino acid sequences of the cloned gene (PLB 1) showed 42.3%, 45%, and 47.8% overall sequence identity, with the reported sequences of phospholipase B cloned from Penicillium notatum, Saccharomyces cerevisiae, and Saccharomyces rosei, respectively. Second, using targeted gene disruption, URA blaster, we created C. albicans null mutants which failed to secrete phospholipase B. Third, we tested the ability of these isogenic strain pairs to cause lethality using a murine model of hematogenously disseminated candidiasis. Our data demonstrate that the parent phospholipase-producing strain caused more fatality in mice, while the null phospholipase-deficient strain was avirulent. Importantly, the parent and null mutants had similar growth and germination rates. These data prove that phospholipase B is essential for candidal virulence, and pave the way for studies directed at determining the mechanism/s through which phospholipase modulate candidal virulence. Understanding phospholipase as a common theme in fungal pathogenicity is critical for developing new antifungal strategies based on anti-virulence.

Animals↗
PubMed2005

Safe specimen preparation for electron microscopy of pathogenic fungi by freeze-substitution after glutaraldehyde fixation.

A safe method is described for observing ultrastructure of highly infectious fungi by ultrathin sectioning electron microscopy. The fungal cells were first chemically fixed by glutaraldehyde to kill them. They were then rapidly frozen by propane slush in liquid nitrogen and freeze-substituted in acetone containing 2% osmium tetroxide. This method gave clear cell images with high resolution in a natural state, close to the image obtained by rapidly frozen freeze-substituted specimen of living cells. Although we have demonstrated the utility of this method using Exophiala dermatitidis and Cryptococcus neoformans, it could also be used for observing highly infectious fungi such as Coccidioides immitis.

Freeze Substitution↗
PubMed1998

Colony interaction and secondary metabolite production of cheese-related fungi in dual culture.

Interactions between fungi used as starter cultures (Penicillium roqueforti, Penicillium camemberti, Penicillium nalgiovense, and Geotrichum candidum) and fungal contaminants associated with cheese were investigated on agar medium at two temperatures, 18 and 25 degrees C. Mutual inhibition on contact was the most common interaction observed. The only other interaction observed was inhibition of the contaminant, while the starter continued to grow, especially in dual cultures involving G. candidum as the starter culture. Dual cultures involving G. candidum showed inhibition of production of the mycotoxins mycophenolic acid, roquefortin C, chaetoglobosin A, and cyclopiazonic acid produced by the contaminants. An unknown metabolite was detected in considerably larger quantity in dual cultures involving G. candidum compared to detection in single cultures. There was no correlation between detection of this metabolite and the observed interactions. The results show that G. candidum plays a major role in interactions between fungi on cheese.

Cheese↗
PubMed1999

Production of lipase by soil fungi and partial characterization of lipase from a selected strain (Penicillium wortmanii).

Filamentous fungi from soil were screened for their ability to produce lipase. Among 56 filamentous fungi tested, one strain identified as Penicillium wortmanii was selected as the highest lipase producer. Maximum lipase production (12.5 U/ml) was obtained in 7-days cultures utilizing 5% (w/v) olive oil as the carbon source. Optimum pH and temperature for crude lipase were 7.0 and 45 degrees C, respectively. The enzyme was stable at 40 and 45 degrees C and it retained about 55% of its activity when heated at 50 degrees C for 1 hour.

Culture Media↗
PubMed1997

[An investigation of precipitation of airborne fungi particles in the rooms of university library].

Precipitation of airborne fungi particles in the rooms of an University library and the influencing factors were studied in May 1994 with the fallen plate method. The total average precipitation of airborne fungi particles was 11.68 per dish in 5 minutes. The differences were significant from different room patterns, floors and times, so were the humidity assayed. The book-store rooms and reading rooms had an average precipitation of 15.01 and 8.35 per dish in 5 minutes respectively (P < 0.05), and humidity of 41.7 and 11.4 percent respectively (P < 0.01). The influencing factors were: different floors and room patterns, the people's activity, the different time, humidity, ventilation and book pollution.

Air Microbiology↗
PubMed1998

Antifungal activity of a new triazole, voriconazole (UK-109,496), compared with three other antifungal agents tested against clinical isolates of filamentous fungi.

Voriconazole is a new triazole antifungal agent with potent activity against yeast and moulds. We investigated the in vitro activity of voriconazole, itraconazole, amphotericin B and 5-flucytosine against 51 clinical isolates of filamentous fungi. Overall, voriconazole was active (MIC50, 0.5 mg l(-1) and MIC90, 8 mg l(-1)) against these mould isolates. Voriconazole was most active against P. boydii (MIC50, 0.12 mg l(-1)) and Aspergillus spp. (MIC90, 0.5 mg l(-1)) and least active against Fusarium spp. (MIC90, 8 mg l(-1)) and Rhizopus spp. (MIC50, 8 mg l(-1)). Voriconazole was more active than amphotericin B against Aspergillus spp. and P. boydii. By comparison with itraconazole, voriconazole was more active against all isolates except Rhizopus spp. Based on these results, voriconazole has promising activity against commonly encountered isolates of filamentous fungi and its clinical usefulness should be established by further studies.

Amphotericin B↗
PubMed1998

A study of keratinolytic fungi in mountain sediments. I. Hair-baiting data.

Sediments form mountain streams in Brenna (Beskid Slaski) were examined for keratinolytic fungi. A rare psychrophilic dermatophyte, Keratinophyton ceretanicus, occurred abundantly in the sediments. The qualitative and qualitative compositions of keratinolytic fungi depended on the water contamination with sewage and on the contents of plant organic material, small mineral particles and salts in the sediments.

Arthrodermataceae↗
PubMed1999

Targeting cell wall synthesis and assembly in microbes: similarities and contrasts between bacteria and fungi.

icrobial cells possess a form of exoskeleton called the cell wall that protects the organism from osmotic pressure and environmental insults. Synthesis of the various building blocks that make up the cell wall occurs in the cytoplasm, and thus microbial cells face specific biochemical and biophysical problems related to the polymerization, transport, and assembly of building blocks into the final wall structure at an extra-cellular site. Cell walls must also be metabolically and structurally pliable in order to allow for processes such as repair, secretion, DNA exchange, and cell division. In some cases, bacteria and fungi use similar mechanisms, to accomplish synthesis and assembly, while in other cases each used divergent strategies to accomplish specific functions. This review will summarize recent advances in our understanding of fungal and bacterial cell wall synthesis and assembly. We will compare specific pathways used by both fungi and bacteria, paying particular attention to identifying those areas where what is known in one system may point to approaches to solving unanswered questions in the other. The structure, chemical properties, and mechanism of action of select natural and synthetic products which inhibit synthesis or assembly of cells walls will be discussed in terms of similarities in the structures, and/or steps in the synthetic process targeted. In addition, new targets in the pathways will be presented along with recent approaches to the discovery and design of novel inhibitors.

Amino Acid Sequence↗
PubMed1999

The antimicrobial efficiency of Piper betle Linn leaf (stalk) against human pathogenic bacteria and phytopathogenic fungi.

The in vitro antimicrobial activity of different varieties of Piper betle Linn, leaf stalk extracts were studied against human pathogenic bacteria and phytopathogenic fungi by comparing the results with standard microbial susceptibility testing biodiscs. The ethyl acetate and ethanol extracts of all the four varieties have shown significant activity against bacteria Vibrio cholerae ogawa, Staphylococcus aureus, Diplococcus pneumoniae and Klebsiella aerogenes. The hexane and benzene extracts have shown moderate activity, while other extracts have shown poor or no activity. In the same way ethyl acetate and ethanol extracts of all the varieties have shown moderate to significant activity against most of the fungi tested, while other extracts showed poor or moderate activity.

Anti-Bacterial Agents↗