Production of hormones by fungi.

Twenty species of filamentous fungi were tested for their gibberellin and sterol production, with emphasis on the action of some factors on these products. While all cultures produced both gibberellin and sterol in variable amounts, Aspergillus flavus, A. niger, A. ochraceus, Cladosporium cladosporioides, Gibberella zeae, Penicillium funiculosum, P. italicum and P. rubrum were the best producers. The isolates of A. niger isolated from soil and P. italicum isolated from citrus fruit were selected for further studies. Gibberellin was highly excreted by A. niger in medium fortified with 0.3:0.3 mol nitrogen-phosphorus ratio. On the other hand, sterol was accumulated in P. italicum by vegetable oils more than fruit oils. However, in shaken culture, the organic and olive oils retarded sterol formation with enhanced accumulation of fatty acids.