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BioEnergy

1. Bioengineering and selection for biodiesel production in bacteria

Lead Project PIs: Lykidis,Athanasios, Maria Billini, Parwez Nawabi and Kyrpides, Nikos

Biodiesel is an alternative fuel composed of fatty acid alkyl esters (FAAE). The most common form of biodiesel is fatty acid methyl esters. They are produced chemically through the reaction of triacylglycerols (TAG) with methanol in the presence of a catalyst. The main sources of TAG in the US are soybean oil and yellow grease, but in both cases current and future production costs are estimated to remain substantially higher than petroleum based products. However, metabolic engineering presents an opportunity to generate microbial strains that will accumulate biodiesel precursors (TAGs or free fatty acids - FFA) leading to lower cost production lines.

Our research aims to combine biochemical and metabolic engineering approaches with experimental evolution to generate bacteria with enhanced capabilities of FFA, TAG or FAAE production. To achieve this, our plan involves bioengineering of carbon flux towards production of bio-oils in bacteria. Fatty acid synthesis in bacteria is tightly regulated at multiple points and is coupled to membrane phospholipid biosynthesis by transcriptional and biochemical controls. Our experimental approach aims to circumvent these regulatory mechanisms and generate strains with altered anabolic and/or catabolic pathways, thus channeling the majority of intracellular carbon towards lipid molecules. We are also exploring the enhancement of bio-oil production in engineered microbes by selection in continuous cultures for a better integration of introduced genes and pathways into their new genomic and cellular contexts. This type of bacterial engineering for bio-oil production entails the transfer of genes from very divergent lineages. We employ experimental evolution approaches to enhance the co-adaptation of the foreign genes and the host cell, in terms of transcriptional regulation, codon bias and other aspects of gene expression and also select for strains with maximum lipid accumulation. Our long-term goal is to understand the molecular mechanisms regulating carbon allocation to lipids and oil accumulation in bacteria
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2. Enzyme discovery in grass-feeding termites for the depolymerization of lignocellulosic biomass

Lead Project PIs: Philip Hugenholtz, Falk Warnecke, Rudolf Scheffrahn, Natalia Ivanova, Nikos Kyrpides

This project addresses the specific goal of enzyme discovery for the depolymerization of C4 grass biomass. Depolymerization of cellulose (and hemicelluloses) in plant cell walls is currently one of the major bottlenecks for industrial production of cellulosic biofuels. Therefore, we are interested to investigate natural systems evolved to decompose plant cell wall polymers for enzyme discovery. The termite hindgut efficiently transforms plant biomass, including grasses, into sugars, short-chain fatty acids, hydrogen and methane under physiological conditions
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3. Genome Sequencing and Analysis of Cellulose and Xylan degrading organisms

Lead Project PIs: Iain Anderson, Nikos Kyrpides

This project targets the sequencing, analysis and identification of novel enzymatic activities from organisms that are known to degrade cellulose and xylan.
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