A proteomic analysis of the effects of environmental factors on hydrogen production in the cyanobacterium Anabaena variabilis.
EMSL Project ID
30452
Abstract
The filamentous cyanobacterium, Anabaena variabilis, produces hydrogen from water, using sunlight as the energy source and carbon dioxide as the carbon source. Hydrogen is made in specialized cells called heterocysts as a byproduct by the enzyme nitrogenase whose primary function is to fix atmospheric nitrogen to ammonia. Using nitrogenase as a hydrogenase A. variabilis produced 1.1 liters of hydrogen per day in a solar bioreactor less than ¼ square meters in area. In order to improve hydrogen production we need a better understanding of the metabolic pathways that sustain and control the amount of hydrogen produced in the heterocyst. The goal of this research is to use a proteomic analysis to better understand cellular changes in response to environmental carbon and nitrogen signals and the role these signals play in the modulation and integration of the biochemical pathways that support nitrogen fixation and hydrogen production in A. variabilis.
The approach to be used in this research will be comparison of cellular proteins over time in response to changes in the carbon (fructose versus carbon dioxide) and nitrogen sources (ammonium versus atmospheric nitrogen) supplied to the cells. The proteome changes will be correlated with physiological changes, particularly those related to nitrogen fixation and hydrogen production. This includes rate of cell growth, heterocyst differentiation, nitrogenase activity, and amount of hydrogen produced.
This research will provide for the first time important information on how perturbations in the environment, in terms of carbon and nitrogen, affect the protein composition of the cells. These protein changes in turn control the pathways for heterocyst formation, energy production and reductant pools that ultimately lead to more or less hydrogen production. Understanding these pathways will help to define environmental conditions that will best support sustained hydrogen production by A. variabilis. Hydrogen production by this strain offers the potential for a renewable, sustainable, solar powered biofuel.
The proteome analysis of multiple samples in a temporal sequence cannot be done using traditional proteomic techniques. The PNNL facility contains a "bottom-up" comprehensive proteomics approach, commonly referred to as the accurate mass and time (AMT) tag approach, which bypasses the need for solid phase 2-D gels. The proteomic analysis techniques developed by Dr. Lipton and others at PNNL have been shown to be effective tools for such an analysis. These facilities with the expertise of Dr. Lipton and her colleagues will be essential for the success of the project.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2008-09-30
End Date
2009-09-30
Status
Closed
Released Data Link
Team
Principal Investigator