Ascomata usually globose, consisting of spore “cysts”, with smooth apparently acellular walls. Paraphyses absent. Asci deliquescent at a very early stage, very difficult to observe. Ascospores spherical, sticky, aseptate, smooth-walled, not dispersed in clusters. Anamorph Chrysosporium-like.
Bettsia is best-known as an inhabitant of beehives. Unlike the other member of this order Ascosphaera Olive & Spiltoir, which is parasitic on the larvae and which has aggregated ascospores which are dispersed in “spore balls”, Bettsia is a saprobe, and the only species B. alvei is also found as a spoiler of foodstuffs with a high osmotic potential. See Skou (1972, 1975) for further information.
Bettsia alvei (Betts) Skou; anamorph Chrysosporium farinicola (Burnside) Skou
Colonies rapidly growing, white or becoming pale greenish or pale brown. Ascomata 15-42 µm diam, very variable in shape, but most usually ± spherical. Ascospores 3-5 µm diam, spherical. Conidia formed singly at the ends, on short protrusions, or intercalary, sometimes in short chains, separating by the breaking down of the intervening cell walls, 6-11.5 x 4.5-9 µm, ± hyaline, rather thick-walled, smooth, aseptate, the terminal conidia globose to clavate and the intercalary conidia usually barrel-shaped.
Apart from the importance of this fungus to apiarists, it is sometimes isolated from foods with high sugar contents, such as dried fruit (Pitt & Hocking, 1985a). These authors separate Chysosporium fastidium Pitt from the anamorph of Bettsia alvei on the basis of growth rates, colony pigmentation and conidial size, but van Oorschot (1980) did not distinguish between them.
Other anamorphic fungi which may be related to Bettsia alvei include Chrysosporium inops Carmichael and C. xerophilum Pitt, which lack lateral conidia and does not grow so rapidly on sugar-rich media. C. inops has been isolated from dried fruit, powdered spices and a starch mould for a gelatin-containing confection, and C. xerophilum from prunes and stored maize (Pitt & Hocking, 1985a).