Pigments, Growth and Photosynthesis in Cultures of Two Chrysomonads, Coccolithus huxleyi and a Hymenomonassp.

Abstract

The two chrysomonads, Coccolithus huxleyi and a Hymenomonas sp., contained chlorophylls a and c, carotene and fucoxanthin, and a number of minor xanthophylls. Coccolithus huxleyi was rich in chlorophyll c and had a chlorophyll a:c ratio of 1-5:1[center dot]0; in Hymenomonas the ratio was 5:1. Incubation of broken-cell preparations at high light intensities resulted to the decomposition of chlorophyll a, whereas chlorophyll c was stable under these conditions. This photochemical bleaching of chlorophyll a shifted the spectrum from 678 to 674 m[mu], with a difference spectrum showing a maximum at 680 m[mu]. Maximum photosynthetic rates of 150-200 [mu]moles CO2/mg. chlorophyll a+c/hr were reached in 10-day cultures. Maximum populations of 106 organisms/ml, for Hymenomonas and 107 for C. huxleyi were reached in about 14 days. Hymenomonas grew best at light intensities of 800 ft.c. or higher, whereas growth of C. huxleyi was independent of light intensity above 60 ft.c. Maximum photosynthetic rates were obtained at a light intensity of 3500 ft.c.