The effect of light on growth and sporulation of certain fungi

Summary The response of the fungi investigated to duration of exposure to light varies with the variation in the light intensity employed. Using relatively low intensity light (160 and/or 300 foot candles/inch²), the growth ofMyrothecium verrucaria &Pestalotia gracilis was not affected by the increase in the time of light exposure, while that ofPleurotus ostreatus was checked. Fruiting under the same conditions was hastened on exposure to light. Under higher light intensity (950 foot candles/inch²), growth ofMyrothecium was not affected, while that ofPestalotia andPleurotus decreased as the daily period of exposure to light increased. Pleurotus cultures exposed continuously to light showed practically no growth, and combined addition of malt and yeast extracts had a noticeable growth promoting effect on cultures exposed continuously to light, but not significantly on those kept in the dark. This was explained by assuming the presence in malt and yeast extracts of light sensitive growth promoting substances. The effect of light on growth ofPleurotus was found to be concerned with both cell mechanism and medium: light probably inhibits inside the cell the synthesis of one or more substances essential for growth and at the same time it favors the breakdown in the medium of one or more substances required for growth.