Growth of Fungi in Sea Water

GRAY, WILLIAM D. (The Ohio State University, Columbus), PATRICK V. C. PINTO, AND S. G. PATHAK. Growth of fungi in sea water medium. Appl. MNicrobiol. 11:501-505. 1963.-The effect of sea water on protein synthesis and growth of some species of Fungi Imperfecti was investigated. The dry weight of mycelia was greater from sea water medium than from distilled water medium in most instances; however, in a few there was a marked reduction in growth. The beneficial effect could not be ascribed to sodium choride or phosphate ion but may be due to the magnesium ion in sea water. This is indicated by the increase in mycelial yield and protein synthesis, even above that obtained with sea water, when magnesium ion was added to the medium. The reduction in yield and protein synthesis in some instances may be attributed to metal interactions; this possibility is being investigated further. At the initiation of an extensive program designed to explore the potential of fast-growing form species of Fungi Imperfecti as synthesizers of edible protein (Gray, 1962a), it was necessary to devise a single medium in which many such organisms would grow. The medium finally selected was a variation of one which had been used for other culture work in this laboratory and was compounded as follows: dextrose, 20.0 g; KH2PO4, 5.0 g; NH4NO3 or NH4Cl, 0.6 or 1.0 g; corn steeping liquor, 2.0 ml; trace elements solutions, 1.0 ml; FeCl3 solution (1.92 g per liter), 1.0 ml; ZnSO4 .7H20 solution (44 g per liter), 1.0 ml; vitamin solution, 1.0 ml. The pH was adjusted to 6.0 with 0.1 N NaOH, and distilled water was added to a final volume of 1 liter. The stock vitamin solution and the trace elements solution were prepared as follows. The vitamin solution contained: p-aminobenzoic acid, 50.3 mg; thiamine hydrochloride, 99.6 mg; riboflavine, 50.0 mg; niacinamide, 200.0 mg; inositol, 400.0 mg; calcium pantothenate, 200.0 mg; pyridoxine, 50.2 mg; and distilled water to a volume of 1 liter. The solution was refrigerated until use. The trace element solution contained: H3BO3, 0.114 g; (NH4) 6Mio7 024*4H20, 0.484 g; CuSO4*7H20, 0.780 g; M\InCl2 *4H20, 0.144 g; ZnSO4 7H2O, 16.720 g; and distilled water to a volume of 1 liter. 1 Paper no. 659 from the Department of Botany and Plant Pathology, The Ohio State University. 501 The choice of whether NH4NO3 or NH4Cl was used as the nitrogen source for a particular organism was based on results from screening experiments in which it was determined which nitrogen salt permitted greatest yields of dry mycelium during a 4-day growth period in medium adjusted to an initial pH of 6.0. With the better nitrogen salt (for each individual test fungus) as the source of nitrogen, a wide variety of imperfect fungi were examined; as might be expected, their total dry weight yields as well as their protein content varied considerably. Some organisms were so inefficient in the conversion of substrate carbon to tissue carbon that they received no further attention; others were quite efficient in this respect and hence were judged to have greater immediate potential. Consequently, details of optimal temperature, pH, concentration of various medium ingredients, etc. were investigated further. Among the more promising organisms were Heterocephalum aurantiacum and Epicoccum sp., which in large-bottle, aerated cultures yielded 55.2 and 81.7 g, respectively, of dried mycelia from 100 g of glucose. Crude protein content varied from 9.11 to 35.0% (dry weight basis) depending on species and environmental conditions. With results such as those mentioned, it became apparent that, among the Fungi Imperfecti, forms exist which might well be of considerable value in the conversion of cheap carbohydrate and inorganic salts of nitrogen to high-protein fungus mycelium. In view of the carbohydrate excesses and protein deficiencies existing in many areas of the world, such a conversion process could make tremendous contributions to the world protein pool (Gray, 1962b). However, one major criticism of such a process might be that, to attain production of a magnitude that could add significantly to man's protein supply, tremendous volumes of water would be required. In many areas of the world, fresh water simply is not available to the extent that would be required; hence, experiments were initiated to determine whether sea water could be substituted, at least in part, for fresh water in the preparation of culture medium: The isolation of new fungal species from the oceans (Johnson, 1956; van Uden and CasteloBranco, 1961) and the reports (Carlucci and Pramer, 1960a, b; MIacLeod, Onofrey, and Norris, 1954; MIacLeod and Onofrey, 1956; Vishniac, 1955) of the beneficial effect of sea water on growth or product biosynthesis are other factors that prompted investigation of the effect of sea on O cber 3, 2017 by gest ht://aem .sm .rg/ D ow nladed fom GRAY, PINTO, AND PATHAKA water on protein synthesis and growth of the Fungi Im-