, Volume 46, Issue 6, pp 549-554

Effects of pH on the growth rate, motility and photosynthesis inEuglena gracilis

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The influence of pH 3–10 on the growth, motility and photosynthesis inEuglena gracilis was demonstrated during a 7-d cultivation. The cells did not survive at pH<4 and >8, highest growth rate being detected at pH 7. Motility followed a similar patterns as growth rate. Photosynthetic response curves were shown to be of the same type over the whole pH range. High respiration was characteristic for cells grown at pH 5 and 6, the lowest one at 7. At high and also at low pH more active respiration was found which can be considered as a protective response on proton stress. Respiration was not completely inhibited with potassium cyanide. Photosynthesis was the most effective at pH 6; lower and higher pH decreased photosynthetic efficiency. pH affected more the growth rate than the photosynthesis.