Production and characterization of algae extract from Chlamydomonas reinhardtii

Background: Algae offer many advantages as biofuel sources including: high growth rates, high lipid content, the ability to grow on non-agricultural land, and the genetic versatility to improve strains rapidly and produce co-products. Research is ongoing to make algae biofuels a more financially attractive energy option; however, it is becoming evident that the economic viability of algae-based fuels may hinge upon high-value co-products. This work evaluated the feasibility of using a co-product, algae extract, as a nutrient source in cell culture media. Results: Algae extract prepared from autolysed Chlamydomonas reinhardtii was found to contain 3.0% protein, 9.2% total carbohydrate, and 3.9% free α-amino acid which is similar to the nutrient content of commercially available yeast extract. The effects of algae extract on the growth and metabolism of laboratory strains of Escherichia coli and Saccharomyces cerevisiae were tested by substituting algae extract for yeast extract in LB and YPAD growth media recipes. Complex laboratory media supplemented with algae extract instead of yeast extract showed markedly improved effects on the growth and metabolism of common laboratory microorganisms in all cases except ethanol production rates in yeast. Conclusions: This study showed that algae extract derived from C. reinhardtii is similar, if not superior, to commercially available yeast extract in nutrient content and effects on the growth and metabolism of E. coli and S. cerevisiae. Bacto™ yeast extract is valued at USD $0.15-0.35 per gram, if algae extract was sold at similar prices, it would serve as a high-value co-product in algae-based fuel processes.

Degradation and de novo synthesis of D1 protein and psbA transcript levels in Chlamydomonas reinhardtii during UV-B inactivation of photosynthesis and its reactivation.

UV-B induces intensity and time dependent inhibition of photosynthetic O2 evolution and PS II electron transport activity in Chlamydomonas reinhardtii. The D1 and D2 proteins of chloroplast membranes are rapidly and specifically degraded in the course of irradiation of cells to UV-B. Continuous synthesis of the two proteins was essential for the repair of damaged PS II as chloramphenicol accelerated UV-B inactivation of photosynthesis and prevented photoreactivation. Northern analysis revealed that UV-B also affected the expression of psbA gene coding for the D1 protein. Cells showing 72% inhibition of PS II activity, revealed a modest net loss of 25% in the level of D1 protein. This shows that synthesis of D1 protein is not the only component involved in the recovery process. Our results indicate that besides affecting the synthesis of the D1 protein UV-B may impair certain post-translational events, which in turn may limit the repair of damaged PS II.