CARBONYL COMPOUNDS PRODUCED BY CERATOCYSTIS FAGACEARUM

THE OAK wilt fungus, Ceratocystis fagacearum (Bretz) Hunt will often produce sporulating mats on the outer face of the wood and the inner face of the bark of diseased trees. Fresh mats tend to be gray or tan in color and they are covered with conidiophores bearing conidia. The mats darken with age and finally disintegrate. G-enerally a pair of cushion-like structures will develop near the center of each mat. The pressure generated by the developing mats is often great enough to rupture the bark and create a moist chamber in which the mycelial mats develop and produce spores. The fungal mats give off a fruity odor which serves to attract sapor fungus-feeding insects of which nitidulids and Drosophila appear to be particularly important. The present investigation is concerned with the nature of the odorous constituents produced by the oak wilt fungus in laboratory culture. MATERIAL AND METHODS Cultural techniqueThe organism used in this study was obtained from Dr. J. E. Kunts, Department of Plant Pathology, University of Wisconsin, and it was maintained on potato-dextrose agar slants at 20 C. Erlenmeyer flasks (250 ml) containing 50 ml of potato-dextrose (5%) broth were inoculated on a rotary shaker at 250 rpm for four or five days at 25 C. These flasks then served as the inoculum for large (2500 ml) flasks containing 650 ml of potatodextrose (5%) broth. Generally eighteen such flasks were incubated on a reciprocal shaker with a stroke length of four inches for 2-3 days at 25 C. Method of separation At the end of the growth period the cells and medium were placed in a large distilling flask (10 liters) and distilled in two 5-liter batches. The aqueous distillate from 30 liters of medium was extracted with ether in a liquid-liquid extractor for several days. The ether extract was treated with dilute aqueous KOR until the extract remained distinctly basic. This fraction containing the volatile acids, phenols and enols was set aside for later investigation.