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Improvement of industrial solventogenic clostridia through genetic modification is an effective approach to enhance the economics of current acetone, butanol and ethanol (ABE) fermentation technology, among which, gene expression is one of main technical means.However, during the expression of genes in clostridia through plasmid or integration into chromosome, well-characterized and fine-tuning synthetic biology toolbox is still deficient.This limited the operability in genetic modification of clostridia.In this study, Clostridium acetobutylicum, the model strain of solventogenic clostridia, was chosen as the research subject.First, a series of native strong promoters were found and identified according to the data from our previously finished microarray analysis.Then, we chose three promoters-Pthl, Pptb and Padc,which were commonly used in C.acetobutylicum for gene overexpression, for random mutagenesis and screening by using reporter system.Meanwhile, RBS regions of the three promoters were also optimized.Thereafter, a series of artificial gene expression elements was obtained, covering from 1/100 to 30-fold expression levels of the original promoters.The relationship of promoter sequences and strengths was analyzed, based on artificial neural network algorithm, for rational design and construction of novel synthetic promoters.This work enriched and assessed novel promoters for gene overexpression in solventogenic clostridia, which paved the foundation for further subtle genetic modification in these important industrial bacteria.