Original paper
Mixotrophy in two species of Ochromonas (Chrysophyceae)
Holen, Dale A.
Nova Hedwigia, Beihefte Beih. 136 (2010), p. 153 - 165
42 references
published: Jun 24, 2010
published online: May 28, 2020
DOI: 10.1127/1438-9134/2010/0136-0153
ArtNo. ESP051013600011, Price: 29.00 €
Abstract
Mixotrophy is a nutritional strategy whereby photosynthesis and heterotrophy are used to varying degrees to support maintenance and growth of the organism. Two species of Ochromonas (Chrysophyceae) were isolated which are morphologically distinct. The SEM isolate is approximately 4 µm in diameter and appears to be at the heterotrophic end of the nutritional spectrum exhibiting a growth rate on bacteria of 3.26 d–1 and 3.96 d–1 in the light and dark, respectively. Its growth on an inorganic medium was 0.26 d–1. Light had no effect on measured ingestion rates of approximately 5 bacteria flagellate–1 h–1. Ochromonas pinguis, approximately 12 µm in diameter and highly vacuolated, exhibits better growth in the light (1.35 d–1) than the dark (0.31 d–1) when fed bacteria. Its growth rate on an inorganic medium (non-axenic) was 0.29 d–1. It exhibited low ingestion rates in the light and the dark of 0.4 and 0.05 bacteria flagellate–1 hr–1, respectively, and may have an obligate requirement for particulate food. Cellular Chl a in the SEM isolate decreases under conditions of rapid phagotrophic growth regardless of light, whereas O. pinguis maintains a relatively high Chl a concentration under all conditions.
Keywords
Mixotrophy • Ochromonas • Chrysophyte • Chrysophyceae • O. pinguis