Maria Ghirardi

Dr. Maria Ghirardi is a principal scientist at NREL, a research associate professor at the Colorado School of Mines, and a Renewable and Sustainable Energy Institute (RASEI) Fellow. She is involved in both basic and applied research and has had extensive experience working with photosynthetic organisms.

Dr. Ghirardi's work at NREL involves photobiological hydrogen production and covers metabolic, biochemical, and genetic aspects of algal metabolism.

Dr. Ghirardi co-discovered a sulfur-deprivation process, which allows sustained hydrogen production from algae. In addition, her team identified three enzymes required for the assembly of [FeFe]-hydrogenases, which led to the development of a bacterial system for production of large quantities of active algal hydrogenase enzyme, a major breakthrough in research. They also initiated the use of molecular dynamics to create computational simulations of O₂ and H₂ gas diffusion through the hydrogenase enzyme, which led to the identification of two access pathways for O₂ to the catalytic site of the enzyme.

This approach is now extensively used by groups in Europe to engineer oxygen tolerance into [NiFe]-hydrogenases. In collaboration with Dr. Matt Wecker from Genebiologics, Dr. Ghirardi developed a new selection method to isolate algal mutants with improved H₂-producing capability, and made improvements in hydrogen photoproduction resulting from both physical and genetic manipulations. She also reported that algae can produce dramatically more hydrogen via the sun when the gas-phase to liquid-phase volume ratio in a bioreactor is increased. The observation helped bump up algae as major players in the search for the best alternative fuel of the future.

Currently, Dr. Ghirardi’s work involves a systems biology study of the role of the redox electron mediator ferredoxin in algal metabolism. Her group was able to express six ferredoxins in the bacterium Escherichia coli, which allowed them to purify each protein and biochemically/biophysically characterize each of them. When used in pull-down assays, they picked up different interactors, leading to hypotheses related to their physiological role in the alga that are being gradually tested in the laboratory.

Dr. Ghirardi has authored more than 120 publications, holds four U.S. patents, and has been featured as an invited speaker in many national and international conferences.

Photosynthesis: electron transport, regulation, energy transduction, ferredoxins, in vivo measurements

Biohydrogen: algal hydrogenases, photoproduction, pathways, applications

Chlamydomonas: physiology, molecular engineering, biofuel pathways, photobioreactors

Algal biofuels production; expression of heterologous proteins/pathways