The physiological responses of one algae species Scenedesmus quadricauda to ammonium and alanine

Abstract In order to explore the role of inorganic and organic nitrogen on physiological process of Scenedesmus quadricauda, we studied the influence of two nitrogen compounds, ammonium and alanine nitrogen on growth, physiological characteristics. Chlorophyll a and maximal photochemical quantum yield of PSII (Fv/Fm), maximum electron transport rate (ETRmax) and Saturating Light intensity (Ik) were measured by Phyto-PAM under the concentration of nitrogen 0.5, 1.0, 2.0, 5.0, 10, 20, 50 mg/L. Results indicated that Chlorophyll a of Scenedesmus quadricauda was the lowest in 0.5 mg/L and 50 mg/L, and it was the highest value in 5 mg/L and 10 mg/L in ammonium nitrogen treated group. In alanine experiment group, Chlorophyll a of Scenedesmus quadricauda was raised with the increase of alanine concentration and was positive relation with alanine concentration. These results showed that ammonium (<5 mg/L and >20 mg/L) inhibited the growth of Scenedesmus quadricauda and that alanine nitrogen is more easily for Scenedesmus quadricauda to take up. Fv/Fm, ETRmax and Ik of Scenedesmus quadricauda showed different tendency between ammonium and alanine experiment group. These parameters showed higher in 5 mg/L and 10 mg/L than that of the other concentration in ammonium experiment group. In alanine experiment group, Fv/Fm, ETRmax and Ik of Scenedesmus quadricauda were rising with higher alanine concentration and the fluctuation of these values of these parameters was in a small range. Scenedesmus quadricauda was sensitive to low ammonium concentration (<5 mg/L) and high ammonium concentration (> 20 mg/L). The higher alanine concentration promoted the growth of Scenedesmus quadricauda.