(161e) Application of Omics Technologies in n-Biobutanol Production By Metabolically Engineered C. Tyrobutyricum

Application of Omics technologies in n-biobutanol production by metabolically engineered C. tyrobutyricum   

Chao Ma*, Ningning Xu, and Margaret Liu

As a sustainable and environmentally friendly biofuel with similar energy intensity to petroleum gas, biobutanol is an excellent alternative for fossil fuel. The metabolically engineered acidogenic C. tyrobutyricum has been used to produce biobutanol through genetic engineering such as ack gene knockout (ACKKO) and adhE2 gene synthesis (ACKKO-adhE2) in previous studies. To further engineer C. tyrobutyricum, it is essential to understand the mechanism of host cell regulation of biobutanol generation. In this study, Omics technologies (i.e. proteomics and metabolomics) were applied to investigate the key enzymes and critical metabolism activities responsible for the high yield, productivity, and selectivity of biobutanol. First, the 2-L free-cell fermentations were performed in 3-L stirred tank bioreactors to compare the biobutanol and biobutyrate productions from glucose among wild type, ACKKO mutant and ACKKO-adhE2 mutant. A high butanol titer of 14 g/L was achieved by ACKKO-adhE2, and high butyric acid titer of 36 g/L was obtained by ACKKO. Second, the global proteomics profiling and metabolomics maps of these three strains were investigated and compared. It is found that, as compared to wild type and ACKKO, the ACKKO-adhE2 had lower intracellular expression of pyruvate: ferredoxin oxidoreductase and hydrogenase in the hydrogen generation pathway, but higher bifunctional acetaldehyde-CoA/alcohol dehydrogenase in the butanol formation pathway. These findings indicated the critical role of reducing power in butanol production and demonstrated the possibility of further improvement of biobutanol production by increasing NADH accumulation in the ACKKO-adhE2 mutant of C. tyrobutyricum. In future, novel engineered C. tyrobutyricum will be rationally designed to achieve higher biobutanol production by integrating the Omics investigation with metabolic engineering.      

Authors:

Chao Ma

Department of Chemical and Biological Engineering

The University of Alabama

Hauser Hall R116

301 7^th Avenue

Tuscaloosa, AL 35405

(Email): cma3@crimson.ua.edu

(Phone): 205-292-8115

Ningning Xu

Department of Chemical and Biological Engineering

The University of Alabama

Hauser Hall R116

301 7^th Avenue

Tuscaloosa, AL 35405

(Email): nxu2@crimson.ua.edu

(Phone): 205-348-7340

Margaret Liu, PhD

Assistant Professor

Department of Chemical and Biological Engineering

The University of Alabama

Hauser Hall R116

301 7^th Avenue

Tuscaloosa, AL 35405

(Email): mliu@eng.ua.edu

(Phone): 205-348-0868