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PubMed2001

Comparison of morphogenetic networks of filamentous fungi and yeast.

Fungi generally display either of two growth modes, yeast-like or filamentous, whereas dimorphic fungi, upon environmental stimuli, are able to switch between the yeast-like and the filamentous growth mode. Signal transduction pathways have been elucidated in the budding yeast Saccharomyces cerevisiae, establishing a morphogenetic network that links cell-cycle events with cellular morphogenesis. Recent molecular genetic studies in several filamentous fungal model systems revealed key components required for distinct steps from fungal spore germination to the maintenance of polar hyphal growth, mycelium formation, and nuclear division. This allows a mechanistic comparison of yeast-like and hyphal growth and the establishment of a core model morphogenetic network for filamentous growth including signaling via the cAMP pathway, Rho modules, and cell cycle kinases. Appreciating similarities between morphogenetic networks of the unicellular yeasts and the multicellular filamentous fungi will open new research directions, help in isolating the central network components, and ultimately pave the way to elucidate the central differences (of many) that distinguish, e.g., the growth mode of filamentous fungi from that of their yeast-like relatives, the role of cAMP signaling, and nuclear division.

Aspergillus↗
PubMed1991

In vitro antagonism of bioluminescent fungi by Trichoderma harzianum.

Two species of bioluminescent fungi, Panellus stypticus and Omphalotus olearius were placed in contact with three different strains of interfungal pathogenic Trichoderma harzianum. Subsequent light emission by the luminous fungi and advance of the interfungal pathogens were compared. Relative differences among the pathogens were reflected in their rate of mycelial advance, the total area over which they produced spores upon the host fungi, and decreases in host bioluminescence. After ten days differences in the total surface areas of spore production varied from 1 to 53 per cent. Differences in the reduction of bioluminescence of the same material ranged over 2 orders of magnitude. Final reduction in luminescence ranged over 6 orders of magnitude. A marked reduction in bioluminescence was observed to precede the advance of spore production. The greatest reduction in luminescence was correlated with the presence of T. harzianum hyphae. Two strains of T. harzianum, NRRL 1698 and ATCC 58674, were effective against both bioluminescent fungi within the study period while a third strain, NRRL 13019, was only effective against Omphalotus olearius.

Agaricales↗
PubMed1982

Nutritional requirements of keratinophilic fungi and dermatophytes for conidial germination.

Germination of spores of Chrysosporium crassitunicatum, Nannizzia fulva (+), Nannizzia fulva (-) and Trichophyton equinum was studied in the presence of various carbon and nitrogen sources. Effect of different temperatures on spore germination was also determined. Maximum spore germination within 24 hours was recorded when glucose was used as a carbon source for all the test fungi. Except sodium nitrate all the inorganic nitrogen sources enhanced the spore germination at 0.05% concentration. Most of the organic nitrogen sources used were found to be stimulatory for the spore germination of test fungi. Optimum temperature i.e. 28 degrees C supported maximum spore germination of all the test fungi within 24 hours. C. Crassitunicatum, N. fulva (+), N. fulva (-) could germinate upto 35 degrees C but beyond that no spore germination was noticed in these fungi. T. equinum could germinate at a higher temperature of 40 degrees C but the percentage of germination was very low.

Arthrodermataceae↗
PubMed1994

Comparison of four media for the isolation of Aspergillus flavus group fungi.

Four agar media used to isolate aflatoxin producing fungi were compared for utility in isolating fungi in the Aspergillus flavus group from agricultural soils collected in 15 fields and four states in the southern United States. The four media were Aspergillus flavus and parasiticus Agar (AFPA, 14), the rose bengal agar described by Bell and Crawford (BCRB; 3), a modified rose bengal agar (M-RB), and Czapek's-Dox Agar supplemented with the antibiotics in BC-RB (CZ-RB). M-RB was the most useful for studying the population biology of this group because it permitted both identification of the greatest number of A. flavus group strains and growth of the fewest competing fungi. M-RB supported an average of 12% more A. flavus group colonies than the original rose bengal medium while reducing the number of mucorales colonies and the number of total fungi by 99% and 70%, respectively. M-RB was successfully employed to isolate all three aflatoxin producing species, A. flavus, A. parasiticus and A. nomius, and both the S and L strains of A. flavus. M-RB is a defined medium without complex nitrogen and carbon sources (e.g. peptone and yeast extract) present in BC-RB. M-RB should be useful for studies on the population biology of the A. flavus group.

Agar↗
PubMed1996

Influence of a subinhibitory dose of antifungal fatty acids from Sporothrix flocculosa on cellular lipid composition in fungi.

Antifungal fatty acids produced by the biocontrol fungus Sporothrix flocculosa were studied on the basis of their effect on growth and cellular lipid composition of three fungi, Cladosporium cucumerinum, Fusarium oxysporum, and S. flocculosa, whose growth was decreased by 51, 33, and 5%, respectively, when exposed to 0.4 mg fatty acid per ml. The sensitivity to fatty acid antibiotics from S. flocculosa was related to a high degree of unsaturation of phospholipid fatty acids and a low proportion of sterols. The major responses of sensitive fungi to sublethal doses of antifungal fatty acids from liquid culture of S. flocculosa were: (i) a decrease in total lipid; (ii) an increase in the degree of fatty acid unsaturation (18:1 > 18:2 > 18:3); (iii) an increase in free fatty acids and phosphatidic acid and a decrease in total phospholipids; and (iv) an increase in sterol/phospholipid ratio. These modifications in lipid composition led to an increase in membrane fluidity in sensitive fungi as demonstrated by assessment of fluoresence anisotropy using liposomes and 1,6-diphenyl-1,3,5-hexatriene probe. This alteration in the physical state of lipids appears to be responsible for the previously demonstrated alteration of membrane structure and function in fungi confronted to S. flocculosa.

Antifungal Agents↗
PubMed2002

Effect of berberine and (+/-)-bicuculline isolated from Corydalis chaerophylla on spore germination of some fungi.

Berberine and (+/-)-bicuculline were isolated from roots and leaves, respectively, of Corydalis chaerophylla. Both were effective in vitro against spore germination of some plant pathogenic fungi (Alternaria brassicicola, A. brassicae, A. cheiranthi, A. melongenae, A. solani, Colletotrichum musae, C. falcatum, Curvularia penniseti, C. lunata, C. maculans, C. pallescens, Curvularia sp., Erysiphe pisi, E. cichoracearum, Erysiphe sp., Fusarium udum, Helminthosporium spiciferum, H. penniseti, H. frumentacei, Heterosporium sp., Oidium erysiphoides and Ustilago cynodontis). Berberine and (+/-)-bicuculline significantly inhibited spore germination of all the fungi at concentrations of 100-1000 ppm. Berberine was effective against all the fungi at all concentrations; most of the fungi did not germinate at 1000 ppm. H. penniseti conidia did not germinate at any concentration of (+/-)-bicuculline. U. cynodontis was the least sensitive fungus at lower concentrations but 800 ppm dose was highly effective.

Antifungal Agents↗
PubMed2005

Phylogenetical approach to isolation of white-rot fungi capable of degrading polychlorinated dibenzo-p-dioxin.

A degradation experiment on PCDDs and phylogenetical analyses were carried out on newly isolated 2,7-dichlorodibenzo-p-dioxin (2,7-diCDD)-degrading white-rot fungi, strains BMC3014, BMC9152, and BMC9160. When these fungi were incubated with tri- or tetraCDDs, the substrates were degraded efficiently, and hydroxylated metabolites were detected. On the other hand, 1,3,6,8-tetrachlorodibenzo-p-dioxin was not decreased, and no metabolites were detected. Phylogenetic analysis of internal transcribed spacers (ITSs) containing rRNA gene sequence (ITS-rDNA) clarified that these strains belonged to the genus Phlebia and were closely related to the fungi Phlebia lindtneri, strains MZ-227 and MG-60, which had both been isolated as 2,7-diCDD-degrading fungi in our previous study. Based on this phylogenetical relationship, other Phlebia genera species were used for a degradation experiment on 2,7-diCDD and 1,3,6,8-tetraCDD. Phlebia acerina and Phlebia brevispora degraded 2,7-diCDD about 40 and 80%, respectively, over 14 days of incubation. It became clear that P. brevispora can degrade 1,3,6,8-tetraCDD and transform it to monohydroxy-tetraCDD, monomethoxy-tetraCDD, dimethoxy-tetraCDD, dimethoxy-triCDD, and 3,5-dichlorocatechol in the treatment cultures. In this paper, we could clearly prove for the first time by identifying the metabolites that white-rot fungus P. brevispora could degrade the recalcitrant dioxin, 1,3,6,8-tetraCDD.

Basidiomycota↗
PubMed2000

Differential expression of manganese peroxidase and laccase in white-rot fungi in the presence of manganese or aromatic compounds.

White-rot fungi (basidiomycetes) play an important role in the degradation of lignin which is, beside cellulose, the major compound of wood. This process is catalyzed by ligninolytic enzymes, which are able to cleave oxidatively aromatic rings in lignin structure. Manganese peroxidase and laccase of white-rot-fungi are the most important of these among the ligninolytic enzymes. In addition, they are able to degrade xenobiotic aromatic polymers, persisting as environmental pollutants. Manganese and aromatic compounds have often been discussed as being inducers, enhancers or mediators of these ligninolytic enzymes. It is known that supplementing the growth medium with either Mn2+, veratryl alcohol or coal-derived humic acids leads to significantly enhanced extracellular ligninolytic activities. Measuring the amount of expressed mRNA of the two enzymes by quantitative RT-PCR provided evidence that the expression of manganese peroxidase was induced in the three tested white-rot fungi, Clitocybula dusenii b11, Nematoloma frowardii b19, and a straw-degrading strain designated i63-2. Laccase, on the other hand, was expressed in all three fungi with a significant basic activity even without inducer added. However, since the level of laccase mRNA was higher in cultures supplemented with any one of the tested inducers, we conclude that both manganese and the aromatic substances also increase the expression of laccase.

Basidiomycota↗
PubMed1996

Two-step degradation of pyrene by white-rot fungi and soil microorganisms.

The effect of soil microorganisms on mineralization of 14C-labelled pyrene by white-rot fungi in solid-state fermentation was investigated. Two strains of white-rot fungi, Dichomitus squalens and a Pleurotus sp., were tested. The fungi were incubated on milled wheat straw contaminated with [14C]pyrene for 15 weeks. CO2 and 14CO2 liberated from the cultures were determined weekly. To study the effect of soil microorganisms on respiration and [14C]pyrene mineralization in different periods of fungal development, the fungal substrate was covered with soil at different times of incubation (after 0, 1, 3, 5, 7, 9 or 11 weeks). The two fungi showed contrasting ecological behaviour in competition with the soil microflora. Pleurotus sp. was highly resistant to microbial attack and had the ability to penetrate the soil. D. squalens was less competitive and did not colonize the soil. The resistance of the fungus was dependent on the duration of fungal preincubation. Mineralization of [14C]pyrene by mixed cultures of D. squalens and soil microorganisms was higher than by the fungus or the soil microflora alone when soil was added after 3 weeks of incubation or later. With Pleurotus sp., the mineralization of [14C]pyrene was enhanced by the soil microflora irrespective of the time of soil application. With D. squalens, which in pure culture mineralized less [14C]pyrene than did Pleurotus sp., the increase of [14C]pyrene mineralization caused by soil application was higher than with Pleurotus sp.

Antibiosis↗
PubMed2002

Cloning and genetic analysis of subtilases in sapstaining fungi.

In order to assess the genetic variance of a group of homologous subtilases in sapstaining fungi, molecular techniques were employed. First, PCR screening with degenerate primers and dot-blot analyses were used to screen 31 different isolates, representing nine species, of sapstaining fungi for the presence of subtilase-like sequences. Restriction fragment length polymorphism PCR and sequence analysis techniques were then used to determine the inter- and intraspecies variation of these genes. A labelled chemiluminescent probe was then used to screen an Ophiostoma floccosum 387N genomic library for subtilase genes. Over ten positive clones were found and one was subcloned and sequenced. Randomly amplified cDNA ends PCR techniques were then employed to obtain full-length subitilase gene sequence information from isolates of four different species. The obtained sequences were found to be homologous with other fungal subtilases and common structural features of the inferred proteins with proteinase K were apparent. Southern blot analysis was used to verify and determine the copy number of the subtilase genes in these fungi. In the work presented here, it was found that all of the isolates tested seemed to contain some sort of subtilase gene sequence and that there was inter- and intraspecies variation in the number and type of subtilase genes present. The data indicated that three distinct groups of subtilase genes are present in sapstaining fungi. However, individual isolates were found to contain only one or two of these gene types.

Amino Acid Sequence↗
PubMed2002

Phosphorus, arbuscular mycorrhizal fungi and performance of the wetland plant Lythrum salicaria L. under inundated conditions.

The role of arbuscular mycorrhizal (AM) fungi in aquatic and semi-aquatic environments is poorly understood, although they may play a significant role in the establishment and maintenance of wetland plant communities. We tested the hypothesis that AM fungi have little effect on plant response to phosphorus (P) supply in inundated soils as evidenced by an absence of increased plant performance in inoculated (AM+) versus non-inoculated (AM-) Lythrum salicaria plants grown under a range of P availabilities (0-40 mg/l P). We also assessed the relationship between P supply and levels of AM colonization under inundated conditions. The presence of AM fungi had no detectable benefit for any measures of plant performance (total shoot height, shoot dry weight, shoot fresh weight, root fresh weight, total root length or total root surface area). AM+ plants displayed reduced shoot height at 10 mg/l P. Overall, shoot fresh to dry weight ratios were higher in AM+ plants although the biological significance of this was not determined. AM colonization levels were significantly reduced at P concentrations of 5 mg/l and higher. The results support the hypothesis that AM fungi have little effect on plant response to P supply in inundated conditions and suggest that the AM association can become uncoupled at relatively high levels of P supply.

Environment↗
PubMed2003

Effects of cadmium on growth and glucose utilisation of ectomycorrhizal fungi in vitro.

Effects of Cd on growth and glucose utilisation of Paxillus involutus, Rhizopogon subcaerulescens and Suillus bovinus were investigated in vitro in liquid culture. S. bovinus was the species most sensitive to Cd in terms of dry matter production and P. involutus was less sensitive than R. subcaerulescens. Greater production of hyphae of P. involutus than the other fungi appeared to confer some degree of Cd resistance, possibly by binding Cd onto cell walls. Growth of the three fungi was increased by glucose addition. While Cd significantly reduced dry matter production of the fungi, there were no significant differences in glucose consumption caused by Cd treatment. This suggests that the use of glucose might have been diverted to detoxification and/or repair mechanisms. Further studies on respiration rates and energy metabolites of these fungi under Cd exposure are needed in order to clarify the results of the present study.

Basidiomycota↗
PubMed2005

Arbuscular mycorrhizal fungi associated with the Meliaceae on Hainan island, China.

Species richness, spore density, frequency of occurrence, and relative abundance of AM fungi were determined in rhizosphere soil samples from nine tropical rainforest sites on Hainan island, south China, and the arbuscular mycorrhizal (AM) status of members of the Meliaceae was examined. All 28 plant taxa investigated (25 species including two varieties of 1 species and three varieties of another) were colonized by AM fungi. The mean proportion of root length colonized was 56% (range 10-95%). Vesicles were observed in 27 and hyphal coils in 26 of the 28 plant taxa. Mycorrhizas were of the Paris-type or intermediate-type, with no Arum-type mycorrhizas observed. Species richness of AM fungi varied from 3 to 15 and spore density from 46 to 1,499 per 100 g rhizosphere soil. Of 33 AM fungal taxa in five genera isolated and identified, 18 belonged to Glomus, 9 to Acaulospora, 1 to Entrophospora, 2 to Gigaspora, and 3 to Scutellospora. Acaulospora and Glomus were the dominant genera identified. Glomus claroideum was the taxon most commonly isolated, with a frequency of occurrence of 56.5% and relative abundance of 10.4%. A positive correlation was found between percentage of root length colonization and species richness. However, there was no correlation between spore density and percentage of root length colonized by AM fungi.

China↗
PubMed2006

Arbuscular mycorrhizal fungi associated with sedges on the Tibetan plateau.

The arbuscular mycorrhizal (AM) status of nine dominant sedge species and the diversity of AM fungi in Tibetan grassland were surveyed in the autumn of 2003 and 2004. Most of the sedge species and ecotypes examined were mycorrhizal, but Carex moorcroftii and Kobresia pusilla were of doubtful AM status, and Kobresia humilis was facultatively mycorrhizal. This is the first report of the mycorrhizal status of eight of the nine sedge species examined. Intraradical vesicles and aseptate hyphae were the structures most frequently observed. Appressoria, coils, and arbuscules were found in the roots of a few sedge species. A strong negative correlation was found between soil organic matter content and the extent of mycorrhizal colonization. Using trap cultures, 26 species of AM fungi belonging to six genera, Glomus, Acaulospora, Paraglomus, Archaeospora, Pacispora, and Scutellospora, were isolated from the soil samples collected. The frequency of occurrence of different taxa of AM fungi varied greatly. Glomus and Acaulospora were the dominant genera, and Acaulospora scrobiculata was the most frequent and abundant species. The species richness of AM fungi was 2.73 in the study area. Species richness and diversity index differed among the sedge species but were not correlated with soil factors such as pH, available P, or organic matter content.

Colony Count, Microbial↗
PubMed2006

Effects of three AM fungi on growth, distribution of glandular hairs, and essential oil production in Ocimum basilicum L. var. Genovese.

The essential oils of basil are widely used in the cosmetic, pharmaceutical, food, and flavoring industries. Little is known about the potential of arbuscular mycorrhizal (AM) fungi to affect their production in this aromatic plant. The effects of colonization by three AM fungi, Glomus mosseae BEG 12, Gigaspora margarita BEG 34, and Gigaspora rosea BEG 9 on shoot and root biomass, abundance of glandular hairs, and essential oil yield of Ocimum basilicum L. var. Genovese were studied. Plant P content was analyzed in the various treatments and no differences were observed. The AM fungi induced various modifications in the considered parameters, but only Gi. rosea significantly affected all of them in comparison to control plants or the other fungal treatments. It significantly increased biomass, root branching and length, and the total amount of essential oil (especially alpha-terpineol). Increased oil yield was associated to a significantly larger number of peltate glandular trichomes (main sites of essential oil synthesis) in the basal and central leaf zones. Furthermore, Gi. margarita and Gi. rosea increased the percentage of eugenol and reduced linalool yield. Results showed that different fungi can induce different effects in the same plant and that the essential oil yield can be modulated according to the colonizing AM fungus.

Mycorrhizae↗
PubMed2003

Salt-induced changes in lipid composition and membrane fluidity of halophilic yeast-like melanized fungi.

The halophilic melanized yeast-like fungi Hortaea werneckii, Phaeotheca triangularis, and the halotolerant Aureobasidium pullulans, isolated from salterns as their natural environment, were grown at different NaCl concentrations and their membrane lipid composition and fluidity were examined. Among sterols, besides ergosterol, which was the predominant one, 23 additional sterols were identified. Their total content did not change consistently or significantly in response to raised NaCl concentrations in studied melanized fungi. The major phospholipid classes were phosphatidylcholine and phosphatidylethanolamine, followed by anionic phospholipids. The most abundant fatty acids in phospholipids contained C16 and C18 chain lengths with a high percentage of C18:2Delta9,12. Salt stress caused an increase in the fatty acid unsaturation in the halophilic H. werneckii and halotolerant A. pullulans but a slight decrease in halophilic P. triangularis. All the halophilic fungi maintained their sterol-to-phospholipid ratio at a significantly lower level than did the salt-sensitive Saccharomyces cerevisiae and halotolerant A. pullulans. Electron paramagnetic resonance (EPR) spectroscopy measurements showed that the membranes of all halophilic fungi were more fluid than those of the halotolerant A. pullulans and salt-sensitive S. cerevisiae, which is in good agreement with the lipid composition observed in this study.

Ascomycota↗
PubMed2004

Relative fibrolytic activities of anaerobic rumen fungi on untreated and sodium hydroxide treated barley straw in in vitro culture.

The fibrolytic activities of rumen fungi were studied in terms of dry matter loss, plant cell wall degradation and enzyme (cellulase and xylanase) activities, when grown in vitro on either untreated or sodium hydroxide treated stems of barley straw over a 12 day period. Changes in fungal growth, development and overall biomass were followed using chitin assay and scanning electron microscopy. Treatment with sodium hydroxide resulted in a decrease in the NDF content together with the disruption of cuticle and the loosening and separation of the plant cells within the straw fragments. The enzyme activities of the anaerobic fungi have a high positive correlation (R(2)=0.99) with their biomass concentration assessed by chitin assay indicating that chitin is a valuable index for the estimation of the fungal biomass in vitro. The anaerobic fungi produced very extensive rhizoidal systems in these in vitro cultures. After incubation with rumen fungi, dry matter losses were, respectively, 35% and 38% for the untreated and treated straw samples and the overall fungal biomass, determined by chitin assay, was significantly higher in the treated samples. In vitro degradation of cellulose and hemicellulose was also higher in the treated than that of untreated cultures. Although, comparatively, xylanase activity was higher than that of cellulase, the cellulose fraction of the straw was degraded more than hemicellulose in both treated and untreated straw.

Journal Article↗
PubMed2005

Degradation of lignin in pulp mill wastewaters by white-rot fungi on biofilm.

An investigation was conducted to explore the lignin-degrading capacity of attached-growth white-rot fungi. Five white-rot fungi, Phanerochaete chrysosporium, Pleurotus ostreatus, Lentinus edodes, Trametes versicolor and S22, grown on a porous plastic media, were individually used to treat black liquor from a pulp and paper mill. Over 71% of lignin and 48% of chemical oxygen demand (COD) were removed from the wastewater. Several factors, including pH, concentrations of carbon, nitrogen and trace elements in wastewater, all had significant effects on the degradation of lignin and the removal of COD. Three white-rot fungi, P. chrysosporium, P. ostreatus and S22, showed high capacity for lignin degradation at pH 9.0-11.0. The addition of 1 g l-1 glucose and 0.2 g l-1 ammonium tartrate was beneficial for the degradation of lignin by the white-rot fungi studied.

Basidiomycota↗