Spiral Development of Mycelium in Aspergillus niger Colonies

Abstract

DURING a recent study of a large number of strains of Aspergillus niger we observed a morphological feature not hitherto recorded, so far as we know, for the A. niger group. The mycelium growing from a point-inoculation of one strain on a modified Czapek solution agar (normal Czapek solution salts, but 30 per cent sucrose instead of 3 per cent) showed a left-handed twist, or spiral development, when viewed from above in the ordinary way. The word ‘spiral’ is used loosely, for a form which indeed suggests the picture of a spiral nebula. The tracks both of the primary hyphæ and of their lateral branches curved in a counter-clockwise sense as they advanced.