Growth of Cylindrotheca closterium var. californica (Mereschk.) Reimann & Lewin on nitrate, ammonia, and urea

Abstract

Cylindrotheca closterium var. californica (formerly Nitzschia closterium Erhrenberg), a marine diatom, grew on nitrate, ammonia, or urea as a sole source of nitrogen. If the initial concentration of ammonia was 5 × 10^-4M or above, there was a lag period before cell multiplication began. When the three forms of nitrogen were offered in combination, ammonia was used first, followed by urea, and finally nitrate. In the seawater medium used, cell multiplication was always accompanied by a rapid rise in pH of the medium, regardless of the nitrogen source.