ABSTRACT
The heart of industrial biotechnology is fermentation conducted by living catalysts–microorganisms. Obtaining efficient cell factories is therefore an imperative need for a successful industrial production process of any useful products by microbial fermentation. Random mutagenesis followed by selection has traditionally been, and still is, used in the biotechnological industry for strain development, such as for improvement of yield and increasing tolerance to products. Although random mutagenesis has been shown as a powerful approach for generation of genetic diversity of any microorganisms, the direct selection of productive mutants can be very time-consuming and labor-intensive. Microorganisms have evolved and optimized their cellular systems through fine-tuning regulation of a multitude of pathways using many different transcriptional regulatory circuits to cope with different environmental changes and/or stresses. Compared with global rewiring metabolic networks, pumping out the toxic product using exporters would be a more direct strategy for the cell to elicit the tolerance phenotype.
