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Comparative Nutrition of Two Species of Blastocladia

Jean M. Crasemann
American Journal of Botany
Vol. 44, No. 3 (Mar., 1957), pp. 218-224
Stable URL: http://www.jstor.org/stable/2438802
Page Count: 7
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Comparative Nutrition of Two Species of Blastocladia
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Abstract

A detailed study was made of the nutrition of Blastocladia ramosa. For comparison, some aspects of the nutrition of a strain of B. pringsheimii were also examined. Blastocladia ramosa was found to require thiamin and nicotinamide, while the present strain of B. pringsheimii, in additon to these two vitamins, needs p-aminabenzoic acid. Of some 30 substances tested as carbon sources, B. ramosa grew well with glucose, mannose, fructose, maltose, and dextrin. The carbon spectrum of B. pringsheimii was not studied in detail but its ability to use sucrose and starch, in addition to the preceding substances, was corroborated. Both species tolerated fairly high amounts of glucose. Growth of B. ramosa was excellent in concentrations of the sugar ranging from 0.5 to 5.0 per cent; only at 8 per cent was growth completely inhibited. Blastocladia pringsheimii attained the greatest dry weight at a concentration of 5.0 per cent glucose, but grew relatively slowly at this concentration. Both species were able to use ammonium to satisfy their nitrogen requirements. Blastocladia ramosa did not use nitrate under the several different conditions tried. The ability of B. pringsheimii to use nitrate was not studied. Neither species could reduce sulfate. While B. pringsheimii depended solely on methionine for sulfur, B. ramosa could use, in addition, cystine or cysteine. Blastocladia ramosa was found to grow well over a broad pH range (pH 6.5 to 8.2); negligible growth occurred at pH 4.0 or below, and none at 8.5 or above. The effect of aeration on the growth of B. ramosa was studied. Weights for agitated cultures were lower than those for standing cultures, and possible explanations are given. Blastocladia ramosa was shown to be capable of growth under anaerobic conditions. Studies on the growth of B. ramosa in a casamino-acid medium showed that maximum dry weight was obtained on the twelfth day after inoculation. Propagation in this medium was observed to occur through zoospore release from successive generations of plants. About 5 per cent of the sporangia in eight-day liquid cultures were R. S. Their germination was not observed.

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