Respiration of Euglena gracilis grown under conditions of vitamin B 12-sufficiency, -deficiency, and -replenishment

Abstract

Respiration rates were measured in Vitamin B 12-sufficient, -deficient and -replenished cells of Euglena gracilis. With increasing vitamin B 12 deficiency the respiratory rate increases to a maximum value 2-fold higher than that of exponentially-growing vitamin B 12-sufficient cells. Respiratory rates decline sharply in both stationary-phase vitamin-sufficient and advanced vitamin-deficient cells, as a consequence of nutrient depletion from the growth medium. There was no net difference in overall O 2 uptake in vitamin-deficient and -replinished cells. The data indicate that vitamin B 12 deficiency does not deleteriously affect respiration in Euglena.