Nine isolates of a Colletotrichum sp. collected in North America on yellow water-lily (Nuphar luteum subsp. polysepalum) at five locations in the Pacific Northwest (PNW) and one isolate from Nymphaea odorata in Rhode Island were compared to three isolates of C. nymphaeae occurring on Nymphaea alba and Nuphar luteum in Europe. The appressoria of all North American isolates were significantly wider than those of C. nymphaeae. Conidia of the nine PNW isolates were significantly wider than those of both the Rhode Island isolate and C. nymphaeae isolates. All isolates were compared using random amplified polymorphic DNA (RAPD) and restriction fragment length polymorphism of the ITS region (RFLP-ITS). Two distinct clusters were differentiated in the dendrogram based on the RAPD analysis. The ten North American isolates formed one cluster and the European isolates of C. nymphaeae formed a second cluster. The separation of the North American isolates from the European isolates was supported by distinct restriction digest phenotypes of the ITS region. Based on morphological and molecular characterization the North American fungus is proposed as a new species, C. nupharicola.

The yeast–mycelial dimorphic Aureobasidium pullulans var. pullulans was grown in chemostat culture under zinc-limitation at pH values in the range 2–7. Steady state was obtained and the growth yield with respect to zinc was independent of pH. The culture grew entirely as yeast, independently of the pH in the pH interval 3–7. The exopolysaccharide (EPS) production from the yeast cells was highest in the pH range 3–6 with a maximum at pH 4·0. Only little EPS was produced at pH 7·0 and no EPS was produced at pH 2·1. At pH 2·1 about 20% of the total biomass was in the filamentous growth form and some chlamydospores were present. A change in the carbon source from glucose to sucrose resulted in a more than doubling of the steady-state EPS concentration from 3·1 to 6·9 g l−1. A simple mass balance on carbon was constructed which could account for more than 95% of the carbon.

Aspergillus niger, a fungus capable of citric and oxalic acid production, was grown on solid medium amended with selected insoluble metal compounds (ZnO, Zn3(PO4)2 and Co3(PO4)2). While A. niger was able to grow on and solubilize all three metal compounds, a crystalline precipitate was observed to form eventually in the clear zone of solubilization under and around the colony. These crystals were extracted from the agar, examined by SEM and X-ray micro-analysis and identified as metal oxalates by performance hplc and gas chromatography–mass spectrometry. The ability of A. niger to precipitate other metal oxalates was investigated with cadmium, copper and manganese phosphates and strontium nitrate. Metal oxalates were again produced and it was found that the different metals resulted in different and characteristic crystal morphologies. A. niger is therefore capable of transforming inorganic insoluble metal compounds into organic insoluble metal compounds. The significance of this process as a means of toxic metal immobilization is discussed.

Conidia of Metarhizium flavoviride were suspended in oil formulations and received fatty and other acids before germination. This was done by the acids being added either to the conidial suspensions before inoculation onto agar plates or directly into the agar before the conidia were applied. Certain acids of chain lengths C10 and below, including lactic, salicylic, caprylic and capric acids produced significant inhibition of germination when added to the oil formulations. When incorporated into the agar, all acids of C10 and below were inhibitory, with the exception of sebacic and succinic acids. Sebacic acid (a C10 saturated dicarboyxlic acid) and all the longer chain fatty acids sampled produced no inhibition of germination, either when added to the formulation or the agar. Tests were carried out on a sample of conidia which showed no germination; a few acids stimulated some germination. These included sebacic acid and longer chain fatty acids such as stearic and (inconsistently) lauric acids. Conidia from a long term storage experiment showed increased germination on the addition of stearic and/or lauric acids. The inhibitory effect of capric acid on germination was overcome by a 4–15 times higher concentration of stearic acid.

The internal transcribed spacer regions (ITS1 and ITS2) of the ribosomal RNA gene repeat from Phytophthora species were amplified using the polymerase chain reaction and sequenced. Sequences from P. cambivora, P. cinnamomi, P. citricola, P. cryptogea, P. drechsleri, P. fragariae var. fragariae, P. fragariae var. rubi, P. megasperma var. megasperma and P. nicotianae were compared with published sequences and phylogenetic trees were produced. The resultant grouping of species generally agreed with groupings established using classical morphological criteria, primarily sporangial morphology. Amongst species with non-papillate sporangia two clades were evident, one consisting of P. fragariae, P. cambivora and P. cinnamomi and the other of P. megasperma, P. drechsleri and P. cryptogea. The latter three were placed in the tree between the non-papillate groups and the papillate and semi-papillate groups which formed three distinct clades. One group comprised P. citricola, P. citrophthora and P. capsici, another P. megakarya and P. palmivora and a third P. pseudotsugae, P. cactorum, P. idaei, P. nicotianae and P. infestans. More isolates of P. megasperma, P. drechsleri and P. cryptogea will need to be examined to settle more precisely the relationship of these species to the others. PCR amplification of ITS sequences using freeze-thawed mycelial scrapings from pure cultures growing on agar followed by digestion with restriction enzymes is a quick and easy way to compare and identify isolates without the need for laborious DNA extraction procedures. With improved technology, rapid automatic sequencing of PCR-amplified ITS regions is now possible and yields detailed information of relationships within the genus as well as allowing the design of species-specific PCR primers for diagnostic purposes.

Cytoplasmic extracts of Fusarium moniliforme contained a peptidase activity, able to cleave preferentially L-Leu-7-amino-4-methylcoumarin fluorogenic substrate. No activity towards this substrate was detected in various culture media of F. moniliforme supplemented or not with different substrates (bovine serum albumin, bovine haemoglobin, collagen or gelatin), proving that the peptidase was not secreted in these conditions. The cytoplasmic enzyme was purified by high performance liquid chromatography using a combination of an anionic exchange and gel filtration columns. The purified activity gave a single band on sodium dodecyl sulphate-polyacrylamide gel electrophoresis, estimated at Mr 45000 under reducing conditions. The aminopeptidase showed an optimum activity at pH 7·2, an isoelectric point at 4·1, the Michaelis constant was at 50 μm and the Vmax at 12 mM AMC released min−1 mg−1 of protein for L-Leu-AMC. Since this natural peptidase is sensitive to the protease inhibitors 1,10-phenantroline and ethylenediaminetetraacetic acid, it is considered as a metallopeptidase.

Zoospore germination and in vitro growth of Phytophthora palmivora were studied in extracts obtained from healthy, wounded and inoculated cacao stem tissues. Extracts from wounded and inoculated stem tissues of IMC 67 (canker resistant genotype) significantly inhibited (P<0·05) zoospore germination and the growth of P. palmivora compared to healthy tissues and the controls. There was no significant difference in the percentage zoospore germination or the growth of the pathogen in the extracts obtained from P 18, SCA 6 and TSH 1076 (susceptible genotypes) and those of the controls, while extracts from ICS 1 and TSH 1188 (moderately resistant genotypes) gave intermediate effects. Also, germ-tube lengths were significantly shorter in IMC 67 extracts than in the controls, moderate in ICS 1 and TSH 1188 extracts and longest in P 18, SCA 6 and TSH 1076 extracts. Tests for antifungal compounds in extracts indicated the presence of phenols. The variation in inhibitory effects of cacao stem extracts on zoospore germination and in vitro growth of P. palmivora can be used as a criterion for selecting cacao genotypes resistant to canker.

Nia globospora sp. nov., a marine basidiomycete, provisionally put in the Melanogastrales, producing fruit bodies on dead culms of Spartina maritima is described. The species grew on baits that were submerged for a period of 6 months in the Mira River estuary, Portugal. Comparisons with other species of Nia are made.

In a soil survey, nematophagous fungi were recovered less from agar plates sprinkled with forest soil (Quercus ilex subsp. rotundifolia) than from those incubated with agricultural (Citrus orchards) soil. Nematodes were present in all soils. The organic matter was higher in forest soils. Water extracts from forest soils with high levels of phenols, leaf litter and Q. rotundifolia fresh leaves affected the development and growth of common species of nematophagous and entomopathogenic fungi. These results show that phenolics from leaf letter could play an important role in the ecology and biology of these invertebrate pathogens in soil.

Communities of Aspergillus section Flavi resident in soils planted with cotton were compared among several areas in the southern United States. Incidence of A. flavus and A. tamarii differed among areas. A. flavus incidence increased with temperature and decreased with latitude. Less than 1% of isolates were A. nomius or A. parasiticus. A. flavus isolates were assigned to either the S or L strains on the basis of sclerotial morphology. S strain isolates produced numerous small (<400 μm) sclerotia; L strain isolates produced fewer, larger sclerotia. The S strain of A. flavus was found in all areas. Aflatoxin-producing potential of A. flavus differed among areas and was correlated with S strain incidence. L strain isolates produced only 33% as much aflatoxin B1 as S strain isolates. No S strain isolate produced both aflatoxin B1 and aflatoxin G1. Correlations indicated that L strain toxigenicity but not S strain toxigenicity varied geographically. While toxigenicities of most isolates were stable through single conidial transfer, 28% of isolates expressed altered levels of toxigenicity after transfer. The observed differences among communities may reflect geographic isolation and/or adaptation, and may cause different vulnerabilities to aflatoxin contamination among crops planted in diverse locations.

Effect of temperature and water potential on extension rate, extra-resource biomass and fractal dimension of Stropharia caerulea and Phanerochaete velutina growing in trays of soil was determined non-destructively with time, by image analysis. S. caerulea responded differently from P. velutina, mycelial extension and biomass production rates of the former being considerably affected by changes in temperature and water potential, with greater aggregation of mycelia into cords at 25 °C and at and below −0·02 MPa. These morphological changes were reflected in the fractal dimension values. Mycelial extension of S. caerulea on agar was sensitive to temperatures above 25 ° and water potentials below −1·3 MPa. This is the first reported work on abiotic effects on fractal dimension of cord-forming fungi on soil, and these results are discussed in terms of the function of mycelial cords and foraging strategies.

Competition and replacement interactions between species of wood-decomposing basidiomycetes were studied with a culture technique using various sized pieces taken from 6 cm diam. wood discs as a substrate. Based on field studies, 17 species of basidiomycetes, either primary decayers or late successional saprotrophs which show strict dependencies on certain preceding pioneer decayers in the field, were isolated and inoculated on the wood sectors. After precolonization, the sectors were attached to each other pairwise in various species combinations and incubated on water agar. The discs were regularly inspected and photographed for detection of mycelial overgrowth. After 6 months, samples were taken from the wood of the sectors and cultured for identification of prevailing mycelia. Measured by the replacement of opposing fungi, the selective late successional species are more combative than the primary decayers. Species of Antrodiella had the greatest competitive success. The results of our experiment corresponds well with field observations and explain, at least partly, the physiological background of the interactions.

Twenty-six fungi associated with leaf spots of palms in north Queensland have been identified, including 12 ascomycetes, one basidiomycete and 13 deuteromycetes. Eight were identified as species new to science. A new species of Pseudospiropes is described and descriptions of two unnamed species of Glomerella are also given.

The antifungal activity of flavone and flavanone was tested in three different concentrations, 0·5, 2 and 8 × 10−4 M, against 34 fungi. In general, flavone was the substance with the higher activity, and could at 2 × 10−4 M completely inhibit several fungi. No linear relationships between the concentration and the antifungal activity could be observed for some fungi. Chaetomium globosum was the only fungus which was totally inhibited by flavanone at 8 × 10−4 M. Several fungi did, however, show a higher inhibition rate at 2 × 10−4 M.

Ultrastructural details of sporangial plasmodia and zoosporangia of Spongospora subterranea f. sp. nasturtii infecting the roots of watercress were observed using transmission electron microscopy. The plasmodial envelope, the interface between host and parasite, was found to be convoluted, having a large surface area. Pseudo-food vacuoles, formed by convolutions of the plasmodial envelope, contained portions of host cytoplasm. True-food vacuoles containing the remains of host organelles were seen within plasmodia. Similar remains also were seen in the central vacuole. The flagellar apparatus including the kinetosome, with microtubular rootlets, the transition zone, the flagellum and the tapering end-piece were examined and described. These observations are discussed in terms of the nutrition of S. subterranea f. sp. nasturtii, its original classification within the fungi (latterly Plasmodiophoromycetes) and affinities with the protists.

This listing covers the period October 1, 1996 through to October 31, 1996. The last issue of one stop mycology contained an erratum: it covered the period September 1, 1996 to September 30, 1996 and not March 1, 1996 to April 30, 1996. Citations are arranged in groups which roughly correspond with the British Mycological Society's Special Interest Committees.