A METHOD FOR DETERMINING QUANTITATIVE ZINC REQUIREMENTS FOR GROWTH

Abstract
In order to determine the growth of an organism as a rational function of the supply of Zn, it is necessary either to grow the organism under conditions of continuous culture and continuous flow or to measure growth rates as a continuous function of the Zn content of the organism. The latter procedure was developed for the alga Euglena gracilis. Growth was measured by protein content, determined by extraction of cells which had been collected on membrane filters. The Zn content was determined from the Zn-65 content of cells similarly collected and from the specific radioactivity determined by atomic absorption spectroscopy. Growth ratein Euglena was found to be a linear function of the Zn content of the cells.