Studies on the green and blue mold of Satsuma orange (3)

The growth stimulating effect of the contents of Satsuma orange fruit rind to Penicillium digitatum (green mold) and P. italicum (Blue mold) was studied.Extract from the orange rind by 80∼99.5% methanol or 80% acetone showed a promotive effect for the mycelial growth of both fungi. The growth stimulative substance was readily adsorbed by active carbon; and on the agar media containing the rind extract treated with carbon, the mycelial growth of P. digitatum was decreased even when treated with a small amount of carbon (0.5g per 80cc). In the case of P. italicum more vigorous growth was obtained when cultured on the rind extract agar treated with small amount of carbon than on the untreated media. On the media, however, containing the rind extract treated with much carbon (1 to 2g per 80cc) under weakly acidic, the growth of P. italicum was also inhibited as in the case of P. digitatum. From these experimental results it was concluded that the extract from the orange rind had two factors, the one stimulative and the other inhibitory to the growth of P. italicum, and the latter did not play its role in case of P. digitatum.It was indicated that the vigorous growth of P. digitatum on the media of orange rind tissue and also on orange fruit would depend upon this stimulative effect of the rind contents.