The genus Acremonium currently contains approximately 100 species, of which most are saprophytic, being isolated from dead plant material and soil. Many species of Acremonium are recognized as opportunistic pathogens of man and animals, causing mycetoma, onychomycosis, and hyalohyphomycosis. Infections of humans by fungi of this genus are rare, but clinical manifestations of hyalohyphomycosis caused by Acremonium may include arthritis, osteomyelitis, peritonitis, endocarditis, pneumonia, cerebritis and subcutaneous infection. (On left: Acremonium falciforme).
Alternaria is a genus of ascomycete fungi. Alternaria species are known as major plant pathogens. They are also common allergens in humans, growing indoors and causing hay fever or hypersensitivity reactions that sometimes lead to asthma. There are 299 species in the genus; they are ubiquitous in the environment and are a natural part of fungal flora almost everywhere. The club-shaped spores are single or form long chains. They can grow thick colonies which are usually green, black, or gray.
Some Aspergillus species cause serious disease in humans and animals. The most common causing pathogenic species are Aspergillus fumigatus and Aspergillus flavus. Aspergillus flavus produces aflatoxin which is both a toxin and a carcinogen, and which can contaminate foods such as nuts. The most common causing allergic disease are Aspergillus fumigatus and Aspergillus clavatus. Other species are important as agricultural pathogens. Aspergillus spp. cause disease on many grain crops, especially maize, and synthesize mycotoxins including aflatoxin.
Basidiospores are generally characterized by an attachment peg (called a hilar appendage) on its surface. This is where the spore was attached to the basidium. The hilar appendage is quite prominent in some basidiospore, but less evident in others. An apical germ pore may also be present. Many basidiospores have an asymmetric shape due to their development on the basidium. Basidiospores are typically single-celled (without septa), and typically range from spherical to oval to oblong, to ellipsoid or cylindrical. The surface of the spore can be fairly smooth, or it can be ornamented.
Cladosporium is a genus of fungi including some of the most common indoor and outdoor molds. Species produce olive-green to brown or black colonies, and have dark-pigmented conidia that are formed in simple or branching chains.
Asexual reproduction in Ascomycetes (the Phylum Ascomycota) is by the formation of conidia, which are borne on specialized stalks called conidiophores. The morphology of these specialized conidiophores is often distinctive of a specific species and can therefore be used in identification of the species.
Dothideomycetes is the largest and most diverse class of ascomycete fungi. It comprises 11 orders 90 families, 1300 genera and over 19,000 known species. Traditionally, most of its members were included in the loculoascomycetes, which is not part of the currently accepted classification. This indicates that several traditional morphological features in the class are not unique and DNA sequence comparisons are important to define the class.
Epicoccum is a dematiaceous mitosporic mold widely distributed and commonly isolated from air, soil and foodstuff. It is found also in some animals and textiles. It is the common causative agent of leaf spots of various plants.