Microbial Development and Metabolic Engineering

We are developing both photosynthetic and anaerobic microbes for fuels and chemicals production from a variety of feedstocks.

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Featured Publications

Overcoming substrate limitations for improved production of ethylene in E. coli., Biotechnology for Biofuels (2016)

Phosphoketolase pathway contributes to carbon metabolism in cyanobacteria, Nature Plants (2015)

Engineered xylose utilization enhances bio-products productivity in the cyanobacterium Synechocystis PCC 6803, Metabolic Engineering (2015)

The plasticity of cyanobacterial metabolism supports direct CO2 conversion to ethylene, Nature Plants (2015)

View all NREL microbial development and metabolic engineering publications .

Capabilities

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Feedstock Diversity

Our genetically engineered microbes utilize a variety of feedstock including cellulose, xylan, syngas, simple sugars, organic acids, and carbon dioxide (CO₂). We have modified the metabolic pathways in Clostridium thermocellum to increase metabolic flux from cellulose to H₂ and hydrocarbon-based biofuels. By engineering a heterologous xylose pathway, we have enabled Synechocystis 6803 to assimilate xylose and fix CO₂ simultaneously in the light. We have established the syngas fermentation platform in the photosynthetic bacteria Rubrivivax gelatinosus and Chloroflexus aurantiacus to improve CO utilization while probing the underlying regulations. Via improving hydrogenase and RuBisCO (Ribulose-1,5-bisphosphate carboxylase/oxygenase) enzyme activities, we have enhanced CO₂ fixation in the chemolithoautotroph Ralstonia eutropha using H₂ as the growth substrate.

Contact: Pin-Ching Manness

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Synthetic Biology

We have utilized the power of synthetic biology to uncover relevant genetic factors to predictably regulate gene expression and pathway flux to improve productivity of biofuels and chemicals in a variety of microbes. Research is currently underway for the development of broad host range CRISPR/Cas9 strategies, as well as the development of mid- to high-throughput strategies to select/screen for improved pathway flux for biofuel production. Recent successes include identification of native and synthetic promoter and ribosomal binding sites to optimize expression of heterologous proteins in Synechocystis 6803 and the improvement of transformation efficiency in this model cyanobacterium.

Contact: Carrie Eckert

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Systems Biology

Our comprehensive systems biology capabilities include bacterial genome sequencing and annotation, construction of pathway-genome database, transcriptomic analysis using microarray and RNAseq, shot-gun and 2-D gel proteomics, protein interaction network, liquid chromatography-mass spectrometry- (LC-MS-) and gas chromatography-mass spectrometry- (GC-MS-)based metabolomic analysis, and 13C-isotope tracer based metabolic flux analysis. Recently, our isotope-based fluxomics analyses have led to discoveries of novel carbon fixation and conservation pathways in cyanobacteria and in C. thermocellum.

Contact: Jianping Yu

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Genetic Systems

We have developed genetic systems and improved transformation efficiencies in microbes, including cyanobacteria, C. thermocellum, R. eutropha H16, Escherichia coli, and photosynthetic bacteria including R. gelatinosus CBS and C. aurantiacus. Our successes include (1) the development of a thermostable and replicating shuttle vector to stably express genes of interests and achievement of markerless and targeted gene deletion in the thermophilic bacterium C. thermocellum; (2) improvement of genetic tools for the integration of deletions/heterologous genes in the cyanobacteria Synechocystis sp. PCC 6803 and the chemolithoautotroph R. eutropha H16; and (3) the development of a genetic system for gene knockout and heterologous expression in a novel photosynthetic bacteria, R. gelatinosus CBS. We are continuously exploring and creating novel and broad host range tools tailored for individual gene knockout, heterologous gene expression, and metabolic engineering of diverse microbes for strain engineering.

Contact: Katherine Chou