The Sporulation ofPenicillium notatumWestling in Submerged Liquid Culture

Abstract

The initial sporulation time of Penicillium notatum Westling grown in shaken submerged culture inoculated with spores or vegetative mycelia is inversely proportional to the logarithm of the inoculum load, with a minimum time of 17.5 hours in the former and 8 hours in the latter cultures. The development of cultures is divisible into two stages. Firstly, there is a period of vegetative growth, the duration of which depends on the inoculum load, after which the culture can be described as mature. Calcium is not required for the development of this maturity. Secondly, the cultures when mature develop phialides and spores if calcium is added to the medium. The development of phialides and the first spores takes 6 hours from the time of adding calcium and this period is not influenced by the inoculum load of the culture. The medium from a mature culture promoted more rapid sporulation of vegetative mycelia placed in it than did a fresh medium, indicating the presence of a sporulation factor(s) in mature medium. Similar activity was also demonstrated in media which had supported growth of any one of five other Penicillium species or Aspergillus niger. The nature of the sporulation factor is so far unknown.