Microbiological Production of Carotenoids. VI. Some Factors Affecting Sporulation and Growth in the Choanephoraceae

During the course of studies made in our laboratory on the submerged-fermentation production of carotenoids, reported by Hesseltine and Anderson (1957, 1958), Anderson et al. (1957, 1958), and Ciegler et al. (1959a, 1959b), the problem of maintaining consistent, high yields was encountered. This problem stimulated the initiation of a series of experiments on the sporulation and growth of the fungi of the family Choanephoraceae, toward the end of producing inocula of ( +) and (-) strains which would contain equivalent numbers of spores and equal amounts of mycelia. This series of experiments is the subject of the present report. As early as 1879, Cunningham noted that strains of Choanephora inffndibulifera (Currey) Sacc. lost their ability to form conidia after three successive transfers on culture media. On the other hand, Wolf (1917) reported that C. cucurbitarum (Berk. & Rav.) Thaxter could be grown for 15 generations with no resultant decrease in asexual reproduction. Cunningham also reported that sporangia were not seen on the host but that they were produced on colonies growing on exhausted media. The same investigator (1895) reported that the main factors influencing fruiting of C. simsoni Cunn. were nutritional ones. Thus, when nutrients were present in large amounts, no fruiting occurred; with lesser amounts, conidia were produced; and if the nutrients were very poor, only sporangia were formed. Cunningham (1879), as well as Moller (1901), Thaxter (1903), Palm and Jochems (1924) and others, reported that conidia in the Choanephoraceae were formed at night and matured early in the morning. Thaxter (1903) found that C. cucurbitarum produced few fructifications when grown in a saturated atmosphere and that it seldom fruited in test-tube cultures. Saito and Naganishi (1915), studying Cunninghamella mandshurica (Choanephora