海産珪藻<i>Chaetoceros calcitrans</i> f. <i>pumilus</i> TAKANOの増殖と塩化コバルト量との関係

Abstract

Since 1963 the author has carried out studies on improvements of the mass culture media of a marine centric diatom, Chaetoceros calcitrans f. pumilus TAKANO, a useful marine shell larvae food. In the present paper the relative cell growth of this diatom and cobaltous chloride concentration in media is discussed. For the culture experiments, globular flasks of 100ml in volume were used under the following conditions: Temperature, 20.0-27.5°C; specific gravity of media based by filtered natural sea water (Table 1), 22.18-24.56 (σ15); light intensities, 1.5 Klux (the radiated energy from light of 400-700 nm was 4.4 W and from the whole light wave length was 17.3 W), 2.0 Klux (radiated energy from light of 400-700 nm was 5.8 W and from the whole light wave length was 23.0 W) or from direct sun beams (about 7 Klux maximum). The results obtained were as follows: 1. Cell division was influenced a little by a cobalt concentration of 0-49.4 μg Co/l, but was inhibited at 61.8 μg Co/l (Figs. 1, 2, 3). On the other hand, the effective concentration of cobalt, basing on P. C. V. (packed cell volume), was 12.4-37.1 μg Co/l, proving 24.7-37.1 μg Co/l as optimum (Figs. 1, 2, 3). 2. Cobalt was not effective for the cell division of Ch. calcitrans f. pumilus. However, some facts obtained show that Vitamin B12 promotes the cell division of this diatoms, Skeletonema costatum, various species of marine pelagic diatoms and flagellates. Consequently the author came to the conclusion that the cobaltous chloride has a somewhat different effect from that of Vitamin B12 on the acceleration of cell division.