Beauveria
Three species are recognised, two of which are well known pathogens of insects.
Beauvaria bassiana is the most common species and is best known as the causal agent of muscardine disease in silkworms. Beauveria species are occasionally isolated in the clinical laboratory as saprophytic contaminants. Infections in humans are extremely rare.
Beauvaria bassiana showing sympodial development of conidia on a geniculate or zig-zag rachis. Conidiogenous cells are flask-shaped, rachiform, proliferating sympodially and are often aggregated into sporodochia or synnemata. Conidia are hyaline and globose or ovoid in shape.
RG-1 organism.
Morphological description:
Colonies are usually slow growing, usually not exceeding 2 cm in ten days at 20C, downy, at first white, but later often becoming yellow to pinkish. The genus Beauveria is characterised by the sympodial development of single-celled conidia (ameroconidia) on a geniculate or zig-zag rachis. Conidiogenous cells are flask-shaped, rachiform, proliferating sympodially and are often aggregated into sporodochia or synnemata. Conidia are hyaline and globose or ovoid in shape.
Key features:
Hyphomycete showing sympodial development of single-celled conidia on a geniculate or zig-zag rachis emanating from a flask-shaped conidiophore.
Molecular identification:
Specific primers were developed by Hegedus and Khachatourians (1996). Full phylogeny of the genus was provided by Rehner and Buckley (2005). Biogeography of molecular types was characterised by Ghikas et al. (2010).
MALDI-TOF MS:
Cassagne et al. (2011) published a standardised procedure for mould identification in the clinical laboratory.
References:
de Hoog (1972), Domsch et al. (2007), McGinnis (1980), de Hoog et al. (2000, 2015).