Comparative study of the oxygen tolerance of Chlorella pyrenoidosa and Chlamydomonas reinhardtii CC124 in photobiological hydrogen production

Abstract In this study, oxygen tolerance of five photohydrogen-producing green algal species, Chlamydomonas moewusii , Chlorella fusca , Chlorella pyrenoidosa , Chlamydomonas reinhardtii and Scenedesmus obliquus , were first evaluated comparatively. These green algae varied in O 2 -tolerance. C. pyrenoidosa exhibited notable O 2 -tolerance and was investigated comparatively to that of C. reinhardtii . We used an improved O 2 -tolerance detection method to eliminate the effects of O 2 dissolving rate. Results showed that the O 2 I 50 values of C. pyrenoidosa cells ( in vivo ) and cell lysate ( in vitro ) were 139% and 61% higher than those of C. reinhardtii , respectively. Furthermore, owing to the higher O 2 -tolerance, C. pyrenoidosa cells could evolve hydrogen at a higher threshold of O 2 content in the photobiological hydrogen production process and kept releasing H 2 for more than 260 h under continuous illumination compared to 60 h in C. reinhardtii did under the same conditions.