Photo-biological hydrogen production from water using microalgae is developing into a promising clean fuel stream for the future. In this study, microarray analyses were used to obtain global expression profiles of mRNA abundance in the green alga Chlamydomonas reinhardtii at different time points before the onset and during the course of sulphur-depleted hydrogen production. These studies were followed by real-time quantitative RT-PCR and protein analyses. The present work provides new insights into photosynthesis, sulphur acquisition strategies and carbon metabolism under sulphur starvation towards hydrogen production and confirms previous findings on the impacts of sulphur deprivation. For instance, while a general trend towards repression of transcripts encoding photosynthetic genes was observed, the abundance of the LHCBM9 transcript (encoding a major light harvesting polypeptide) and its protein was strongly elevated throughout the experiment while all other LHCBM genes were downregulated. This suggests a major remodelling of the photosystem II light harvesting complex as well as an important function of LHCBM9 under sulphur starvation and photo-biological hydrogen production. This study presents the first global transcriptional analysis of C. reinhardtii before, during and after photo-biological hydrogen production (PBHP)
