Fig. 1

Fluorescence photographs of microalgal mutant Scenedesmus sp. Z-4 staining by Nile red at different light/dark cycles under autotrophic and mixotrophic conditions. a–e autotrophic cultivation; f heterotrophic cultivation; g–j mixotrophic cultivation. a, f light/dark cycle of 0 h/24 h, b, g: light/dark cycle of 6 h/18 h, c, h light/dark cycle of 12 h/12 h, d, i light/dark cycle of 18 h/6 h, e, j light/dark cycle of 24 h/0 h