The diversity, biological activity and secondary metabolite production of fungi associated with marine sponges were investigated in order to assess the potential of these fungi for the production of novel biologically active secondary metabolites. 681 fungal strains were isolated from 16 sponge species from six different locations, representing 13 genera of Ascomycota, 2 of Zygomycota, 37 of mitosporic fungi, and 37 strains of sterile mycelium. The spectrum of fungi from each location was dominated by a few genera of mainly mitosporic fungi that are also commonly encountered in terrestrial habitats.

A high proportion of culture extracts of sponge-associated fungi was biologically active in tests to detect antifungal, antialgal, and antibacterial activity, cytotoxicity and inhibition of reverse-transcriptase and tyrosine kinase. The corresponding chemistry was structurally diverse and related to that of terrestrial fungi. From the biologically active culture extracts of five fungal strains, nine pure compounds were isolated in addition to 18 previously reported.

The adhesion of conidia of Pestalotiopsis neglecta occurs in four stages in a specific manner which allows the first cell most likely to germinate to become firmly attached its substrate while leaving the other two fertile cells free to be dispersed further, thereby increasing the chance of further successful infections. The first stage of adhesion involves the mucilaginous coating acquired from the conidial matrix and appears weak. The second stage of adhesion is also relatively weak and occurs at the bases of the pedicel. The third stage occurs with the release of a fibrillar adhesive substance from along the length of the pedicel to the top of the basal cell and at times a lesser amount of fibrillar material is released from the apical appendages. The fourth stage involves the release of fibrillar material at the point of germtube emergence. The third and fourth stages provide strong attachment.

Aspergillus niger and A. nidulans were grown separately in glucose-limited chemostat cultures on modified Vogel's medium. Periodic selection (the appearance of new mutant populations) in A. niger was determined by monitoring oscillations in the concentration of cycloheximide-resistant mycelial fragments in samples from the fermenter vessel. Using these data, the interval between the periodic selection of each new mutant population was 32±6 generations (mean±S.E.M.). Periodic selection in cycloheximide resistance in three morphologically distinct sub-populations of the A. niger culture averaged 36±2, 31±11 and 28±5 generations and these values were not significantly different from that of the whole population (32±6 generations). Also, it was possible to estimate the rate of evolution taking place in these cultures by monitoring oscillations in the frequency of morphological mutants. The intervals between the periodic selection of morphological mutant populations in A. niger and A. nidulans were 28±3 and 22±2 generations respectively.

An isolate of Coniothyrium minitans did not sporulate on media to which 0·05 mM magnesium was added when κ-carrageenan was used to solidify the medium. Normal conidiation was observed when a technical grade agar or agar-agar was used as the gelling agent. The κ-carrageenan and agars used in this study contained significant amounts of Mg. In the agar media all the Mg present was available to the fungus. By contrast, in the κ-carrageenan gel a large portion of the Mg was bound by the gel and not available. Sporulation of C. minitans was only observed on media containing [ges ]0·17 mM of unbound Mg. The possible role of Mg in the initiation of conidium formation by C. minitans is discussed.

Sequential effects of colonisation by the wood decaying Fistulina hepatica were examined microscopically in naturally infected and artificially inoculated heartwood of pedunculate oak (Quercus robur). For 6 mo, the deposition of brown materials within parenchyma cells containing hyphae was the only visible effect of colonisation. After 12 mo degradation occurred but was initially confined to parenchyma of xylem rays, in which the secondary cell walls showed helically orientated internal cavities containing hyphae, as in a soft rot. The hyphae were covered with a resinous material and persisted in a herringbone pattern after the secondary walls became heavily degraded. The adjacent libriform wood fibres also showed cavity formation. By contrast fibre-tracheids were mainly affected by a brown rot. uv-microscopy indicated that cell types in which the soft rot mode occurred were rich in syringyl lignin, whereas the brown rot was associated with cells rich in guaiacyl lignin. Thus, the present study shows that F. hepatica possesses dual modes of degradation which appear to correlate with the different lignin composition within cell types of oak.

Aspergillus fumigatus is saprotrophic with an unusual ability to colonize the respiratory tract. The mechanisms that permit pathogenicity may have evolved to adapt the fungus to life as a saprobe. To define the nature of these adaptations and identify common themes in fungal pathogenesis to vertebrates, insects and plants, we compared A. fumigatus with a plant pathogen (Haematonectria haematococca) and an insect pathogen (Metarhizium anisopliae) in their abilities to degrade and utilize host-derived macromolecules (horse lung polymers, porcine mucin, hyaluronic acid, alfalfa cell walls and cockroach cuticle). Each fungus produced a similar range of proteases on mucin and lung polymers, and high levels of several glycosidic enzymes on mucin and plant cell walls, which contain inductive carbohydrate substrates. Following 18 h of growth by A. fumigatus at pH 4 or pH 8, the degradation of mucin carbohydrates and mucin protein were approximately 40% and 75% respectively, suggesting that the aspartyl proteases (produced at pH 4) and the subtilisin proteases (produced at pH 8) are more important than carbohydrases for degrading mucin. The highly glycosylated mucin residue remaining after 18 h growth resisted further degradation, in part due to bound sialic acid as A. fumigatus secretes a sulphatase but not sialidase. Hyaluronidase activity (an important virulence factor in bacteria) was not produced by A. fumigatus, M. anisopliae or H. haematococca, but each fungus secreted a range of other enzymes (phospholipase A2, phospholipase C, acid phosphatase, alkali phosphatase, phosphodiesterase and esterase) that are common toxic components of bacteria as well as reptilia and invertebrate venoms. Thus thermotolerant opportunists such as A. fumigatus may sustain themselves and cause disease in human hosts using depolymerases that are widely distributed in fungi and that provide them with the versatility to exploit many environments.

Filtrates from cultures of wild isolates of Phellinus contiguus grown on liquid medium containing malt extract induced precocious fruiting of this resupinate polypore when tested in a bioassay. Active filtrates were analysed using gel filtration, HPLC and GC-MS and were compared with filtrates from single spore progeny, two of which lacked fruiting inducing activity. The active material was polar and heat stable, passed through both anion and cation exchange columns and had a mol. wt less than approx. 1000. Fractionation using HPLC on amino-silica yielded one fraction which was active on its own and a second, later eluting fraction, which had scarcely detectable activity when alone, but when combined with the first fraction had much higher activity than either alone. GC-MS showed that both this first fraction and the most active fraction from P2 gel filtration were rich in mono- and disaccharide sugars. In comparison with fractions from parallel inactive filtrates, all active fractions contained more myo-inositol and a relatively high glucose/disaccharide ratio.

It is suggested that a combination of high concentrations of myo-inositol and apoplastic glucose may be required for initiation of fruiting in P. contiguus. Although additional work is needed, this view is consistent with known features of growth and fruiting in white rot fungi.

Soil yeast occurrence and abundance was studied in brood chambers within mounds of the red imported fire ant, Solenopsis invicta, and adjacent non-mound soil from Texas. Ten yeast species were isolated from fire ant brood chamber soil and 13 from non-mound soil. Relative frequencies of Candida parapsilosis and C. lipolytica were greater in brood chamber soil, and Cryptococcus terreus occurred more frequently in non-mound soil. Rhodoturula rubra, R. minuta, and Candida vini only occurred in non-mound soil. Mean cfu g−1 of soil was greater in brood chamber soil. Fire ants alter the community composition and relative abundance of yeasts within mounds due to creation of unique microhabitat patches.

To study the genetic variability in Glomus mosseae and Gigaspora margarita sequence similarities of ITS regions of rDNA were analysed from spores collected from a permanent pasture and from pot cultures. PCR amplification with the primers ITS1 and ITS4 was performed and products were cloned and sequenced. The sequences from single spores of G. mosseae and Gi. margarita confirmed that there is variation in the ITS region in a single spore. Phenetic analysis of sequences from both species supported the morphological identification which placed the species into two separate groups. Through the analysis of these sequences an estimate of genetic diversity was derived which clearly showed that the three field spores of G. mosseae were at least 2–5 times more genetically diverse than one single spore (field) and a pool of spores (pot culture) of Gigaspora margarita. This demonstrates that a high degree of variation exists in this natural population of G. mosseae.

Of 47 fungi collected from decaying Ocotea wood, 36 exhibited phenoloxidase activity against gallic acid, 40 exhibited it against tannic acid, 33 possessed laccase and 6 possessed tyrosinase. Thus their capacity to produce ligninolytic enzymes indicated that a high proportion of these fungi could cause white rot in Ocotea wood. It was shown that all 21 fungi tested were capable of causing significant weight loss in Ocotea wood blocks in vitro. Basidiomycetes exhibited the greater capacity to cause decay when compared to non-basidiomycetes. The rank order of species in terms of proportional weight reduction in the wood blocks over four months was: Trametes versicolor (28%), Ganoderma australe (16%), Phellinus sp. 2 (15%), Phellinus senex (10%), Stereum ostreum (10%), Loweporus inflexibilis (9%), Stereum hirsutum (8%), P. gilvus (7%), and Schizophyllum commune (2%). The most aggressive non-basidiomycetes, however, were comparable to S. commune, and these were: Cylindrodendrum album (3%), Cylindrocarpon destructans (2%), Daldinia concentrica (2%) and Nodulisporium sp. (2%).

Oosporein was the only major secondary metabolite produced by three commercial isolates of the entomopathogenic fungus Beauveria brongniartii in submerged cultures and on sterilised barley kernels. None of the other toxins (bassianin, beauvericin and tenellin) normally produced by Beauveria species were detected by sensitive HPLC and MS techniques. The maximum amount of oosporein produced in batch reactors was 270 mg l−1, after 4 days incubation, while that produced on sterilised barley kernels ranged between 2.0 and 3.2 mg kg−1, after 14 days incubation. The mean amount of oosporein detected in cockchafer larvae infected with B. brongniartii was 0.23 mg. Melocont®-Pilzgerste, a commercial product based on B. brongniartii, was not phytotoxic to Lepidium sativum and Phleum pratense nor were fungal metabolites detected in these indicator plants. No systemic effects of oosporein were observed in treated pasture turf maintained for several months in the greenhouse.

Two unusual species of Acremonium sect. Acremonium, A. borodinense sp. nov. and A. cavaraeanum, are described and illustrated. They were isolated in Japan from rhizosphere soil of sugarcane and an outer wall of a wooden house respectively. A. borodinense is characterized by forming two kinds of conidia, ellipsoidal rough-walled and cylindrical smooth-walled. Of A. cavaraeanum a second isolate has become available; it forms long chains of fusiform conidia, has a luteous reverse and exudes a livid-red pigment into the medium.

Ericoid mycorrhizal fungi can alleviate heavy metal toxicity to their host plant, but the mechanisms that lie behind this increased tolerance are unknown. As a first step in the characterisation of two isolates of Oidiodendron maius from mycorrhizal roots of Vaccinium myrtillus growing in heavily contaminated soils, we investigated their taxonomic position, their mycorrhizal capabilities and their ability to grow in the presence of heavy metals. When growth was compared with isolates from non-polluted soils, a better performance was observed in the presence of increasing concentrations of zinc salts, especially at higher ion concentrations. The mechanisms of tolerance may include the production of mucilage and extracellular pigments.

Although several new techniques for isolating and culturing lichens have been reported in recent years, there is little information available concerning the variability in development of species from different taxonomic groups. A comparison of the early stages of the germination and growth of Xanthoria parietina (Teloschistaceae), Parmelia saxatilis (Parmeliaceae), Physconia distorta and two Diplotomma species (Physciaceae) was performed on two different media: one inorganic, and the other containing 4% glucose (LBM; Lilly-Barnett medium). Different germination and development rates, and isolation success rate (single- and multispore cultures) are reported. The new combination Diplotomma rivasmartinezii (Barreno & A. Crespo) Barreno & A. Crespo is made.

The obligate biotrophic pathogen Plasmodiophora brassicae induces cataplastic galls in the roots of various species of the Brassicaceae. The ecotypes Ze-0, Tsu-0, and Ta-0 of Arabidopsis thaliana carry alleles of a dominant single gene (RPB1) for resistance against this pathogen. The pathotype-specific resistance reactions in the roots were accompanied by a hypersensitive response. Infected cells were surrounded by necrotic boundaries and thereby the pathogen growth was restricted. The pathogen could induce hyperplasia and hypertrophy to a slight extent and develop spores within mini-galls surrounded by the necrotic cells, if it was able to colonise meristematic tissue. Ecotype Ze-0 showed the highest level of resistance to P. brassicae isolate ‘e’ as indicated by the very limited number of infected cells, whereas the resistance of the ecotype Ta-0 was rated lower. The results are discussed in relation to the interaction of the pathogen with Brassica crops.

Thirty-nine ectomycorrhizal isolates of Paxillus involutus, Pisolithus tinctorius, Suillus bovinus, S. luteus and S. variegatus were tested on cadmium, copper, nickel and zinc amended media to determine their in vitro tolerance, measured as inhibition of biomass production. Twenty-one isolates were from heavy metal polluted sites, whereas the others were from non-contaminated soils. There was a strong interspecific variation in metal tolerance. S. luteus, S. variegatus and P. tinctorius were more tolerant of Cu, Cd and Zn when compared with P. involutus, whereas the reverse was true for Ni. A high intraspecific heterogeneity in metal tolerance was also found. EC50 values for isolates originating from polluted sites were not statistically different from EC50 values for isolates originating from non-contaminated sites. The findings are discussed in relation to the potential benefits of ectomycorrhizal fungi in protecting their host plants from metal contamination.

The genetic structure of three newly established Cryphonectria parasitica populations (Choëx, Weggis, Murg) was analysed and compared to an older, post-epidemic population (Claro). Vegetative compatibility (vc) type and DNA fingerprint analysis revealed an almost clonal C. parasitica population in Choëx, Weggis and Murg. These stands are all situated in northern Switzerland, outside the main range of European chestnut. Only one vc type and one dominant DNA fingerprint was found in Choëx and Murg. In Weggis, two vc types and two dominating DNA fingerprints were found. The European Cryphonectria hypovirus (CHV1) was not detected in these three populations. In contrast, the population in Claro, situated within the main range of European chestnut in southern Switzerland, had much higher vc type and DNA fingerprint diversity. DNA fingerprints were correlated to vc types in Claro and in Weggis. Mating type determination revealed one strongly dominating mating type in each of the three northern populations, but not in Claro. From these results we conclude that C. parasitica disseminated almost exclusively by means of asexual reproduction in Choëx, Weggis and Murg, whereas in Claro sexual reproduction also played an important role. Additionally, founder effects and restricted gene flow were dominating factors in shaping the genetic structure of the three northern populations.

Among 46 species of fungi isolated from decaying Ocotea wood, growth differed in response to oxygen stress during a 24 d trial. All fungi grew for one week but during the following 17 d, six different growth responses emerged. In 12 species daily growth rates were initially stimulated, then totally inhibited; in 4 high growth rates were maintained over the 24 d period; in 5 growth rates were similar under both aerobic and anaerobic conditions and then stopped under the latter; in 5 growth rates in both treatments were similar during the whole trial period; in 16 growth was retarded before inhibition, and in 4 growth was retarded without being inhibited. Growth of 91% of the fungi able to produce ligninolytic enzymes was significantly inhibited or retarded in the absence of oxygen. The behaviour of the fungi under oxygen stress conditions is discussed regarding their roles in the colonization and decay of stems of standing Ocotea trees. It is concluded that in standing trees, oxygen stress may exert selective pressure during successive colonisation, and that tolerance to oxygen stress favours Phellinus species and Loweporus inflexibilis in becoming the main climax decay species in Ocotea trees.

Persistence of Aschersonia aleyrodis, a fungal pathogen of whitefly, was studied on cucumber, gerbera and poinsettia. Germination capacity and infectivity of conidia, which stayed on the plants for up to 1 month, were assessed. Average germination of conidia on the leaves was low (< 14%), whereas most of the conidia transferred from the leaf to water agar were viable, even after having been on the leaf surface for 1 month. Germination capacity was highest on cucumber, followed by poinsettia and lowest on gerbera. On cucumber leaves, conidia stayed viable and were able to infect 90% of whitefly nymphs 31 d after spore application. On gerbera, germination capacity decreased considerably from 80% (day 0) to 40% (day 31). This was reflected in nymphal mortality, which declined from 75% to 40%. Despite the high germination capacity (60%) of conidia on poinsettia after an exposure of one month, nymphal mortality decreased from 70% at the day of spore application to 10% after 3 d at leaf surface, and remained low throughout the monitoring period. Relations between germination capacity, infectivity and the host plant environment such as phyllosphere microorganisms, secondary plant metabolites and microclimate are discussed.

Two main taxa of Phomopsis associated with Phomopsis cane and leaf spot disease of grapevine have been recognized in Australian vineyards. The present investigation identifies Diaporthe viticola, recorded for the first time since 1867 on grapevines, as the teleomorph of Taxon 1. Perithecia of D. viticola were found on 1 and 2 year old canes of cvs Chardonnay, Shiraz, Riesling, Cabernet and Pinot Noir in many vineyards in southern Australia. The teleomorph was induced in vitro on oatmeal agar and on sterilised segments of grapevine cane inoculated with isolates of Phomopsis Taxon 1.