Studies on Nitrogen-Fixing Blue-Green Algae. I. Growth and Nitrogen Fixation by Anabaena Cylindrica Lemm

Abstract

The capacity for growth of blue-green algae with molecular N has been found to be of the same order of magnitude as the growth of vigorously growing green algae with nitrate N. An investigation of the nutrient requirements of the blue-green alga A. cylindrica disclosed that Ca was essential for growth whether nitrate or molecular N was used. Previous reports had suggested that Ca was required with molecular N only. The specificity of two elements previously reported to be replaceable in the growth of blue-green algae was established. Ca was not replaceable by Sr nor Mo by V. Growth of Anabaena increased with increasing light intensity up to 16,000 lux. 13 hours of light of an intensity of 16,000 lux each day permitted as rapid growth as 24 hours of illumination. Under the conditions described, a yield of Anabaena of 7-8 g dry weight per 1 of culture solution in 5-6 days was obtained with either nitrate or molecular N.