effects of uncoupling agents on nitrite uptake by Scendesmus obliquus

ABSTRACT

Light increased the capacity for nitrite absorption by Scenedesmus obliquus posaibly through the increased energy supply and/or the increased nitrite reductase activity. Assimilation was observed when normal algal cells were illuminated in the absence of CO[2]under aerobic condition. The rate of assimilation by-carbohydrate-deficient cultures depends on light and the presence of CO[2]. The failure of illuminated carbohydrate-deficient cells to reduce nitrite in absence of CO[2] seems to be due to the exhaustion of the respiratory substrates in the cells. The effect of uncoupling agents was studied in an attempt to clarify the relation between the photochemical reductant and the reduction of nitrite. Addition of DNP or KCN inhibited the utilization of nitrite by about 80% compared to about 28 percent with DCMU. Under heterotrophic conditions inhibition was almost the same. These results indicate that high energy phosphate is involved in the assimilation of nitrite by this alga