David Malloch

Genotypic variation in Penicillium chysogenum from indoor environments

We examined 198 isolates of P. chysogenum recovered from 109 houses in Wallaceburg, Ontario, and 25 culture collection isolates including seven ex-type strains. Multilocus genotypes were determined by heteroduplex mobility assay of regions spanning introns in acetyl co-enzyme A synthase, beta-tubulin, thioredoxin reductase and the internal transcribed spacer regions of the nuclear ribosomal subrepeat. Five unique multilocus haplotypes were revealed without evidence of recombination, indicating strictly clonal population structures. Phylogenetic analysis of allele sequences using maximum parsimony resolved three strongly supported lineages. The dominant clade included more than 90% of house isolates in addition to the notable laboratory contaminant isolated by Alexander Fleming in 1929 in Britain. A second clade contained more than 5% of house isolates clustered with the ex-type strains of P. chysogenum and P. notatum. Follow-up sampling of outdoor air in the locality failed to reveal P. chysogenum, confirming the rarity of this fungus in outdoor air.

THE ORIGIN OF THE ATTINE ANT-FUNGUS MUTUALISM

Cultivation of fungus for food originated about 45-65 million years ago in the ancestor of fungus-growing ants (Formicidae, tribe Attini), representing an evolutionary transition from the life of a hunter-gatherer of arthropod prey, nectar, and other plant juices, to the life of a farmer subsisting on cultivated fungi. Seven hypotheses have been suggested for the origin of attine fungiculture, each differing with respect to the substrate used by the ancestral attine ants for fungal cultivation. Phylogenetic information on the cultivated fungi, in conjunction with information on the nesting biology of extant attine ants and their presumed closest relatives, reveal that the attine ancestors probably did not encounter their cultivars-to-be in seed stores (von Ihering 1894), in rotting wood (Forel 1902), as mycorrhizae (Garling 1979), on arthropod corpses (von Ihering 1894) or ant faeces in nest middens (Wheeler 1907). Rather, the attine ant-fungus mutualism probably arose from adventitious interactions with fungi that grew on walls of nests built in leaf litter (Emery 1899), or from a system of fungal myrmecochory in which specialized fungi relied on ants for dispersal (Bailey 1920) and in which the ants fortuitously vectored these fungi from parent to offspring nests prior to a true fungicultural stage.

A molecular-morphotaxonomic approach to the systematics of the Herpotrichiellaceae and allied black yeasts

The systematics of the Herpotrichiellaceae, a family of loculoascomycetes with predominantly black yeast anamorphs, is reevaluated on the basis of cultural, molecular and morphological criteria. The majority of species of Capronia, the largest genus in this family, possess black yeast anamorphs belonging to the form genera Exophiala, Ramichloridium and Rhinocladiella. Pseudoparenchymatous ascomatal initials and immature ascomata are produced in strains of E. dermatitidis, E. pisciphila and E. salmonis and support the loculoascomycetous affinity of Exophiala. Cladistic analyses of partial sequences from the nuclear small subunit ribosomal DNA gene (18S rDNA) demonstrate that species of Exophiala for which telemorphs are unknown and species of Capronia possessing black yeast anamorphs form a monophyletic group within the Ascomycotina. The Exophiala anamorphs of C. epimyces and C. moravica are described, and Phialophora-like and Ramichloridium synanamorphs are reported for C. acutiseta and C. parasitica, respectively. The genus Acanthostigmella and C. pinicola are excluded from the Herpotrichiellaceae, and the new genus Tyrannosorus is described to accommodate the latter taxon. The position of the Herpotrichiellaceae within the Dothideales sensu lato is discussed.

Chemistry, mineralogy and microbiology of termite mound soil eaten by the chimpanzees of the Mahale Mountains, Western Tanzania

Subsamples of termite mound soil used by chimpanzees for geophagy, and topsoil never ingested by them, from the forest floor in the Mahale Mountains National Park, Tanzania, were analysed to determine the possible stimulus or stimuli for geophagy. The ingested samples have a dominant clay texture equivalent to a claystone, whereas the control samples are predominantly sandy clay loam or sandy loam, which indicates that particle size plays a significant role in soil selection for this behaviour. One potential function of the clays is to bind and adsorb toxins. Although both termite mound and control samples have similar alkaloid-binding capacities, they are in every case very high, with the majority of the samples being above 80%. The clay size material (<2 μm) contains metahalloysite and halloysite, the latter a hydrated aluminosilicate (Al 2 Si 2 O 4 -nH 2 O), present in the majority of both the termite mound soil and control soil samples. Metahalloysite, one of the principal ingredients found in the pharmaceutical Kaopectate is used to treat minor gastric ailments in humans. The soils commonly ingested could also function as antacids, as over half had pH values between 7.2 and 8.6. The mean concentrations of the majority of elements measured were greater in the termite mound soils than in the control soils. The termite mound soils had more filamentous bacteria, whereas the control soils contained greater numbers of unicellular bacteria and fungi.

New concepts in the Microascaceae illustrated by two new species.

The family Microascaceae is discussed in light of past and present research. New concepts of the family are put forward which encompass the results of this research and two new species, Microascus giganteus and Petriella musispora are described. Lophotrichus, Kernia and a new genus, Petriellidium, based on Allescheria boydii Shear are included in the Microascaceae for the first time. Characters of possible future taxonomic interest are also discussed.

Coniochaetones A and B: New antifungal benzopyranones from the coprophilous fungus Coniochaeta saccardoi

Abstract Two new antifungal cyclopentabenzopyran-4-ones, coniochaetones A ( 1 ) and B ( 2 ), have been isolated from liquid cultures of the coprophilous fungus Coniochaeta saccardoi (JS 223). The structures of these metabolites were elucidated based on analysis of 2D-NMR and HRMS data.

Interaction of soil microflora with the bioherbicide phosphinothricin

Abstract Phosphinothricin, a microbial toxin synthesized industrially for chemical weed control and currently under development as a selective weed killer in cultivation of transgenic plants engineered to resist its presence, is investigated for its effects on the distribution of microorganisms in 15 agricultural and non-agricultural soils. In agricultural soils, the presence of 1 mM phosphinothricin reduced the number of fungi isolated by about 20% and bacteria by about 40%. Under these conditions the isolation of bacteria from boreal forest soils was also suppressed by about 20%. Differences in herbicide resistance were confirmed when a random selection of fungi, bacteria and actinomycetes isolated in the absence of herbicide was grown with 1 mM phosphinothricin. Soil isolates growing in the presence of 1 mM phosphinothricin exhibited a wide spectrum of tolerance to increasing herbicide concentration over the range of 0–50 mM phosphinothricin. Of fungal isolates, the plant pathogen Verticilium alboatrum was among the most resistant, while the mycoparasitic species Trichoderma harzianum and T. longipilus were among the most sensitive to the presence of phosphinothricin.

The genus Thielavia

The genus Thielavia Zopf is defined according to revised concepts and the species enumerated. It is suggested that species of Chaetomidium (Fckl.) Sacc. are not sufficiently different from those of Thielavia to warrant generic separation and are nearly all transferred to the latter genus. Short descriptions are provided for all 25 species and varieties of Thielavia together with a synoptic plate for their identification. References are given under each species to published illustrations. Among the excluded species are T. leptoderma Booth which is made the type species of a new genus, Aporothielavia, and T. ovata Booth, transferred to the genus Kernia Nieuwland.

The Trichocomaceae: Relationships with Other Ascomycetes

The Trichocomaceae is a relatively large family of Ascomycetes with members frequently impinging upon human activities. Because of this, they have received considerable taxonomic attention, focussed mainly on their conspicuous ana-morphs. When the holomorphs are examined closely two taxonomic groups or subfamilies become apparent: 1) the Dichlaenoideae, characterized by bivalved ascospores, frequent presence of true cleistothecial peridia, production of various anamorphs including Aspergillus, and a marked affinity for starchy or oily substrata, and 2) the Trichocomoideae, characterized by non-bivalved ascospores, lack of a true cleistothecial peridium, largely Paecilomyces and Penicillium anamorphs, and an affinity for cellulosic substrata. Most morphological features of the Trichocomaceae resemble those of Ascomycetes in other families. In spite of this, an independent terminology has developed in the Trichocomaceae that is often inconsistent with more general usage. Some recommendations are offered to resolve these differences.

SIMILARITY OF AMPHOROMORPHA AND SECONDARY CAPILLICONIDIA OF BASIDIOBOLUS

The life cycles and relationships of a variety of minute fungi occurring on arthropod integuments are poorly known. Species of Amphoromorpha Thaxter are reported from all continents except Australia and Antarctica on arthropods and mucoralean and laboulbenialean fungi. Based upon observations of herbarium specimens and of mites and termites exposed to cultures of Basidiobolus ranarum Eidam, we conclude that species of Amphoromorpha actually may be the secondary capilliconidia of Basi? diobolus spp. Evidence was obtained from morphological similarities of attachment region on the arthropods, shape and method of internal cleavage of the conidia, and opportunity for attachment of conidia to arthropods and fungi in their habitats. Secondary capilliconidia of Basidiobolus appear to be important for dispersal to new substrates in the life cycle of these fungi.