Studies of a Unique Pigment Complex and a Photobiological Reaction in Penicillium Herquei

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Abstract
An investigation was made concerning the influence of light on a variant of P. herquei. It was found that light inhibited the vegetative growth of the organism. The influence appeared to be inversely proportional, i.e., as light intensity increased, the radial extension of the mycelium decreased. It was also found that light exerted a profound influence upon the sporulation and the color of the organism. When grown in total darkness or at high light intensities, over 200 f. c., the organism failed to sporulate. However, it sporulated rather abundantly at 100 f. c. Various aspects concerning the influence of light on the color of the organism were also investigated. It was found that yellow colonies when exposed to sunlight rapidly became green. The results indicated that the reaction was a photocatalytic oxidation, perhaps mediated by a fluorescent pigment. They also indicated that the living organism possessed the ability to reverse the color change, i.e., green to yellow. Various tests were conducted to determine the nature of the pigment complex. It appeared to be composed of at least two fractions. One fraction was not identified; the other fraction, obtained through sublimation, responded positively to tests for quinones and related compounds. It was found to be a pH indicator.