The basic hydrolysis parameters, i.e. molecular weight of substrate, reaction time, pH, temperature, and enzyme and substrate concentration, were standardized to maximize sugar yield from dextran. Thus, a 74% conversion of 4% dextran to sugar syrup was reached in 12 h using 6 dextranase units g−1 hydrolysed substrate. The high concentrations of sucrose in the reaction medium did not affect the hydrolysis efficiency nor the activity of Penicillium notatum dextranase. Action patterns of dextranase from P. notatum on dextran were investigated. Analysis of the dextran hydrolysis end products indicated that P. notatum dextranase was a typical endo-enzyme, and isomaltose and isomaltotriose were identified as the primary final products of dextran hydrolysis.

The fungal pathogen Entomophaga maimaiga, infecting gypsy moth larvae (Lymantria dispar), produces two types of spores; relatively short-lived conidia are produced externally on cadavers and are actively ejected to cause infection during the same season, while azygospores, produced within cadavers, are dormant after formation and survive unfavourable conditions. This is the first record providing experimental proof of differential reproduction resulting from infections initiated by these two types of spores. Cadavers of larvae that had died from infections initiated by azygospores produced only conidia, regardless of host instar or relative humidity after host death. This is in stark contrast to infections initiated by conidia, which could yield either conidia only, azygospores only, or both spore types, with reproductive outcome primarily influenced by host age. Production of only conidia from infections initiated by azygospores increases opportunities for secondary transmission during the eight week field season; if infections initiated by azygospores produced azygospores, chances for amplification of infections with subsequent epizootic development would be decreased.

Mycovellosiella malloti-repandi, M. nerii-indici and M. solanacearum, occurring on Mallotus repandus (Euphorbiaceae), Nerium indicum (Apocynaceae) and Solanum verbascifolium (Solanaceae), respectively, are described and illustrated. The first was collected from the North-Eastern Terai region of India and the other two from Nepal.

Random amplification of polymorphic DNA (RAPD), using both fingerprinting (M13, [GTG]5, [GACA]4) and random [V5] primers, has been used to analyse 145 isolates characteristic of Trichoderma sect. Longibrachiatum and Hypocrea species with anamorphs referable to that section, and to identify strains with named species of sect. Longibrachiatum. To this end, ex-type strains of T. longibrachiatum, T. pseudokoningii, T. citrinoviride, T. parceramosum and T. reesei were analysed, and the similarity coefficients of RAPD characters used as a criterion for the alignment of strains to individual species. The ex-type strains of T. saturnisporum and T. ghanense exhibited the same interspecific similarity index as the other ex-type strains of Trichoderma sect. Longibrachiatum, and clustered well within it and were therefore included into this section. 103 isolates were identified as members of Trichoderma sect. Longibrachiatum and further investigated. Most of the anamorphic isolates could be aligned with T. citrinoviride or T. longibrachiatum, whereas only a few strains of T. saturnisporum and T. parceramosum were found. No naturally occurring anamorphs with homology to the ex-type strains of T. reesei and T. pseudokoningii were found. While T. longibrachiatum and T. citrinoviride overlapped through much of their geographic ranges, the former was present in Africa and India but not in southeast Asia, while the reverse was true of the latter. The African strains of T. longibrachiatum were equally distant from the ex-type strains of T. longibrachiatum, T. parceramosum and T. saturnisporum. The type strain of T. ghanense was identified as belonging to this group. T. pseudokoningii, the anamorph of Hypocrea schweinitzii, was found exclusively in eastern Australia and New Zealand. Attempts to identify potential teleomorphs of the other anamorphs revealed another subgroup of H. schweinitzii, occurring in temperate climates in Europe and U.S.A., as homologous to T. citrinoviride. No Hypocrea strains could be identified as teleomorphs of T. longibrachiatum, T. parceramosum or T. saturnisporum.

Eighty-seven strains belonging to 18 species of Fusarium were characterized by restriction fragment length polymorphism (RFLP) analysis of ribosomal DNA (rDNA). The polymerase chain reaction (PCR) was used to amplify a fragment including internal transcribed spacers and variable domains of the 28S rDNA. Data from RFLP analysis of amplified rDNA using eight frequent-cutting restriction enzymes permitted the definition of 23 rDNA haplotypes. The combination of only four restriction enzymes was sufficient to resolve the 23 haplotypes. Each haplotype could be assigned to a single Fusarium species, except for two haplotypes which were common to two or three closely related species. Polymorphism was found within some Fusarium species. Grouping among Fusarium strains derived from restriction analysis was, on the whole, in agreement with other molecular and morphological classification criteria. Therefore, the PCR/RFLP method described in this paper provides a simple and rapid procedure for the differentiation of Fusarium strains at the species level.

Scolecotheca cornuta gen. et sp. nov. is introduced for a fungus which colonizes and causes lesions on algae which occur on needles of Picea abies in Denmark and elsewhere in Europe. It is characterized by cornute conidiomata and scolecosporous aseptate conidia with a basal lateral appendage. Comparisons are made with other coelomycete genera having cornute to infundibular conidiomata and similar conidial morphology.

A new species of Chaetomium, C. cuyabenoensis, is described from the Ecuador rain forest. It is similar to Chaetomium longicolleum but differs by having smaller and, in face view, strongly limonifom to quadrangular ascospores.

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.

Cerato-ulmin (CU) presence was monitored on cell surface and quantitatively determined in mycelial extracts of the elm pathogens Ophiostoma novo-ulmi (races EAN and NAN) and O. ulmi and of the non-pathogenic O. piceae. CU was detected on the surfaces of Ophiostoma novo-ulmi (races EAN and NAN) and, for the first time, of the weak Dutch elm disease pathogen O. ulmi and the non-pathogen O. piceae. Quantitative determination of CU content in the mycelial extracts of the three species showed that high CU cellular content is associated with high CU content in culture filtrates. The content of CU in biomasses and in culture filtrates was influenced by temperature, growth phase and fungal species or race. CU synthesis occurred during the stationary phase and in the late logarithmic phase when fungi were grown at 23° and 32°C, respectively. High temperatures of growth (32°) did not have a negative effect on the cellular CU content but severely hampered CU secretion in high CU-producers O. novo-ulmi isolates.

Melanographium palmicolum sp. nov. is described and illustrated based on a specimen collected on a decaying rachis of Archontophoenix alexandrae in Hong Kong. It differs from other previously described species of Melanographium by its moderately dense and widely divergent conidiophore fascicles, and the shape and size of its conidia. A key to the eight species currently accepted in the genus is provided, based on the literature.

Penicillin was not detected in Aspergillus nidulans liquid cultures with pelleted morphology (pellets 1–5 mm diam.) but production was observed in cultures with homogeneous filamentous morphologies. Adenylate Energy Charge (AEC) and Oxygen Uptake Rates (OUR) were measured in cultures exhibiting the two morphologies and it was shown that the values of both parameters were lowest in pelleted cultures and highest in cultures with a filamentous morphology. In addition, a third morphological form, ‘micropellets’ with intermediate properties between the other two types was encountered. We propose that oxygen limitation brought about by the mass transfer restrictions of pelleted growth inhibits penicillin production.

We report the first successful culturing and confirmation of identity (via sodium dodecyl sulphate polyacrylamide gel electrophoresis, SDS–PAGE) of Serpula lacrymans (the dry rot fungus) derived from basidiomes and mycelia growing in the ‘wild’. The fungus was found growing on well decayed coniferous wood within the Narkanda region of the Western Himalayas at between 2800 and 3100 m above sea level (a.s.l.). The ‘wild’ habitat of the fungus is described, as is the isolation of Serpula himantioides also found in these regions. Temperature, osmotic potential, initial pH and air-current influenced the average colony extension rate of ‘wild’ and a selection of building isolates on 2% malt extract agar. The ‘wild’ and building isolates behaved as two separate cohorts; the ‘wild’ isolates appeared to be less affected by extremes of temperature, whereas building isolates extended more rapidly at the moderate microenvironmental regimes.

In response to the need for a faster, more reliable method for identifying Phytophthora cinnamomi in cork oak soils in Portugal, a simple, fast, sensitive molecular identification method is described. It is based on a colorimetric assay which involves an oligonucleotide capture probe covalently immobilised on microtitration wells, a multi-biotinylated oligonucleotide detection probe and the PCR-amplified target DNA. The target DNA is a 349 bp DNA fragment partially covering the 3′-translated and 3′-untranslated regions of the cinnamomin gene. When the specificity of the PCR reaction was evaluated in vitro using isolates of P. cinnamomi and eight other Phytophthora species, including the related P. cambivora, it was specific to P. cinnamomi. When 30 isolates of P. cinnamomi from oak roots in southern Portugal were assayed, 26 gave a strong positive response. The assay has a sensitivity of about 2–5 genome equivalents of P. cinnamomi. The reason for the negative response of four isolates remains unclear.

Torrubiella hemipterigena and its anamorph, Verticillium hemipterigenum, are re-described from collections made on leafhoppers in Thailand. A new species, Verticillium pseudohemipterigenum, collected on scale insects on bamboo in Trinidad and Surinam, is proposed. Based on these collections, the taxonomic status of the genera Verticillium and Hirsutella is discussed.

Evidence is presented that the biogenesis of sclerotia in Sclerotium rolfsii is associated with lipid peroxidation. Sclerotial initials show 100-fold increase in lipid peroxides of their total lipids as compared with young mycelia grown under reducing conditions (in 2-mercaptoethanol) in dark and without Fe(II). There was a direct relationship between the number of sclerotia formed and lipid peroxidation levels in the mycelial colonies. Lipid peroxides of possible membranous and cytoplasmic origin were found in sclerotial exudate. In this paper a new approach is advanced for the understanding of the mechanism of sclerotial formation in Sclerotium rolfsii and in other fungi. The data in this work on lipid peroxidation – the most frequently evoked consequence of oxygen free radicals – as well as the data of past experiments, strongly suggest that this phenomenon may be associated with oxidative stress caused by growth conditions.

Previous studies with a monoclonal antibody (designated UB7) raised against isolated haustorial complexes formed by the pea powdery mildew fungus Erysiphe pisi showed that it recognized an abundant glycoprotein found in cell walls and plasma membranes of haustoria and the surface mycelium. In this paper, Western blotting and phase-partitioning in the detergent Triton X-114 have been used to show that the plasma membrane antigens recognized by UB7 comprise a 62 kDa integral glycoprotein and a set of integral membrane glycoproteins of lower molecular weight. A 59 kDa glycoprotein recognized by UB7 has been extracted from the fungus using aqueous buffer, and the evidence suggests that this represents the cell wall form of the antigen. Binding of UB7 is abolished by pre-treatment of glycoproteins with peptide-N-glycosidase, but is retained after endo-F treatment. This suggests that the epitope to which UB7 binds is the innermost N-acetylglucosamine residue of N-linked carbohydrate side chains of glycoproteins, possibly substituted with one or more sugars. When tested for cross-reactivity with other fungi, UB7 bound to some, but not all, of those examined, and recognized different sets of glycoproteins compared with those detected in E. pisi. However, UB7 did not bind to any higher plants nor to any animal glycoproteins tested. This antibody thus identifies a carbohydrate epitope restricted to glycoproteins in a subset of the fungi.

Sclerotinia homoeocarpa is a common and severe fungal pathogen responsible for dollar spot disease on turfgrasses. The RAPD–PCR technique was used to identify genetic variation among 26 isolates of S. homoeocarpa. DNA polymorphisms were detected among different isolates using 15 oligonucleotide primers and a dendrogram was constructed using the unweighted pair-group method with arithmetic averages (UPGMA) for cluster analysis. Isolates from different geographical locations in the United States were separable into three distinct groups based on RAPD profiles and the cluster analysis. These three groups, however, were clearly more closely related to each other than to the isolate from Belize which was unique compared to the other S. homoeocarpa isolates examined. RAPD profiles suggest that transport of the pathogen from east coast to west coast locations in the U.S.A. may account for the recent identification of the disease in the Pacific Northwest. The results indicate that RAPD–PCR is a valuable method for differentiating isolates of S. homoeocarpa.

A novel source of α-amylase has been identified in Pycnoporus sanguineus. Spores incubated in the submerged system using wheat bran as a carbon source showed α-amylase activity. Induction of α-amylase was also observed from mycelium incubated in submerged fermentation (LM4) using starch or wheat bran as the carbon source. The effect of the inhibitors on the production of enzyme by mycelium incubated in the presence of glucose, suggested the existence of catabolic repression. A comparative study showed that in a solid state fermentation system (SSM), even in the presence of high levels of glucose, the production of α-amylase was 4-fold greater than that in a submerged system. High levels of β-glucosidase and xylanase activities were also found in SSM after 72 h incubation. P. sanguineus produces at least three important hydrolytic enzymes using economical procedures.

A new rust fungus on Dioscorea, Cerotelium dioscoreae, sp. nov. is described from Ecuador. Similarity with other phakopsoraceous genera and the assignment of the new fungus to Cerotelium is discussed.

Previously undescribed features on the surfaces of powdery mildew conidia were revealed by the scanning electron microscope (SEM), reinforcing differences observable by light microscopy (LM). Four distinct patterns were observed on the septa and 10 on the outer wall, thus categorizing 15 anamorph taxa. Anamorphs of Leveillula, Phyllactinia and Pleochaeta, all had smooth to moderately verrucose septa, but each bore a different distribution of warts on their verrucose outer wall. Annular septa and an echinulate outer wall were unique for the Oidium anamorph of Blumeria. The remaining powdery mildews, all with Oidium states, had either whorled or fibrillar septa. Those with whorled septa are separated into three newly proposed subgenera: Fibroidium for the anamorphs of Podosphaera and Sphaerotheca having conidia with fibrosin bodies and a smooth outer wall; Octagoidium for the dendritic patterned, eight-sided conidia of Sawadaea; and Setoidium for the anamorph of Cystotheca reflecting the setae on the mycelium. Three new subgenera are proposed for those with fibrillar septa: Reticuloidium for conidia with a roughcast outer wall of Erysiphe sect. Golovinomyces; Graciloidium for the unswollen conidia of Arthrocladiella; Striatoidium for conidia of E. sect. Galeopsidis with a striate outer wall. The name Pseudoidium is retained as a subgenus for the anamorphs of E. sect. Erysiphe, Microsphaera and Uncinula which had conidia with a scaly, fibrous outer wall. The patterns on the outer wall of conidia were frequently modified by secondary creasing. These wrinkling patterns, also observable under the LM, proved useful in identification of anamorphs, especially on herbarium specimens. SEM, LM and host range data were used to construct keys for the prediction of the anamorphs of all the powdery mildew genera found in the U.K. The findings, together with teleomorph criteria, also prompted a revision of the Erysiphaceae.