Figure 1.

C. reinhardtii is not able to grow on exogenous fatty acids. (A) C. reinhardtii culture cell density after 3 d following transfer from TAP medium to minimal medium (MM), TAP, or MM with the addition of butyric acid (C4, BTA) in Tween 80 (FA dispersing agent, Tween), valeric acid (C5, Val A) in Tween 80, or Tween 80 alone. About 5 × 10⁶ cells of strain CC124 or CC4425 were transferred to each new medium for each experiment. The graph shows averages ± standard error mean of three independent experiments. (B) Growth of C. reinhardtii and C. vulgaris cultured on agar plates without light. C. reinhardtii CC124, CC5082, and C. vulgaris (UTEX#395) were cultured for 4 d in TAP, then streaked on agar plates containing either acetic acid (C2 FA, left) or palmitic acid (C16 FA, right) and placed in the dark for 20 d. Tween is a dispersant for palmitic acid but did not affect growth with the acetic acid present. Growth was not observed when C16 FA was used as a sole carbon source in the dark (right Petri plate). (C) Growth of Chlamydomonas CC5082 cultured with different carbon sources. CC5082 was cultured for 14 days in liquid MM that contained Tween and other carbon sources, such as acetic acid, palmitic acid, and glucose. The cells were cultured with or without light. Notice that the cells proliferate in the dark only when acetic acid is in the medium.