Beschreibung:
<jats:p>A simple acrylic plastic pressure vessel was designed for growing photosynthetic organisms under gas pressure and at elevated temperatures. Pressures ranging from 20–50 atm of CO<jats:sub>2</jats:sub> were found to retard <jats:italic>Cyanidium caldarium</jats:italic> growth and to alter its pigmentation. In the cells subjected to this range of pressure an absorption shift of the chlorophyll <jats:italic>a</jats:italic> and carotenoid peak at 432 nm to a shorter wavelength (413 nm) was observed which may serve as an indicator for changes occurring within the algae. It was not observed in cells unaffected by pressure and was reversed in cells retransferred to ambient pressure. Lower hyperbaric CO<jats:sub>2</jats:sub> pressures at room temperature or of 50 atm of argon at 45C permitted growth, and the absorption spectra were like those of cells grown under ambient pressure. Thus the pressure injury apparently was caused by toxicity of the gas (hyperbaric doses of CO<jats:sub>2</jats:sub>) rather than by pressure per se.</jats:p>