Document Type : Original Article
National Institute of Genetic Engineering and Biotechnology, Tehran, Iran
Department of Microbiology, Faculty of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, Tehran, Iran
Department of Cell and Molecular Science, School of Biological Science, Kharazmi University, Tehran, Iran
Department of Microbiology, School of Biology, University College of Science, University of Tehran, Tehran, Iran
Introduction: Biotransformation process has been used in various industries due to its ability to produce valuable chemicals and address environmental concerns. Propylene hydroformylation is a process in which n-butyraldehyde and isobutyraldehyde are produced. N-butyraldehyde is a high valuable chemical with many industrial applications, while isobutyraldehyde produced as a by-product is an environmental pollutant. This study offers a biotechnological approach for conversion of isobutyraldehyde into a high-value substance. An engineered strain of Escherichia coli was developed by genomic insertion of alcohol-dehydrogenase gene (adhA) from Lactococcus lactis which can convert isobutyraldehyde into isobutanol.
Materials and Methods: The adhA gene was engineered to substitute some of its amino acids to result in a more efficient enzyme. Engineered gene was synthesized and introduced into E. coli genome to develop recombinant E. coli EG-296 strain. In addition, by using the Qualiteck-4 software, 16 well-defined experiments (L16 Orthogonal array) with two levels of seven variable parameters were used to optimize the process efficiency.
Results: The findings of this study revealed that the E. coli strain EG-296 is capable of converting isobutyraldehyde into isobutanol. The optimization results showed that optimum medium composition for the highest isobutanol production were 10 g/L glucose or glycerol as carbon source, 10 g/L NH4CL as nitrogen source, mid-log of inoculum age, and 1% inoculum volume in 25ml medium. After optimization, 560 mg/L isobutanol was produced from 600 mg/L isobutyraldehyde with 91% yield.
Conclusions: Recombinant E. coli strain with a relatively optimum medium can be used to remove isobutyraldehyde in refineries or other industries producing this chemical as a by-product.