Genetic Manipulation of Myxobacteria

Genome sequencing of a few myxobacteria has revealed genes for the biosynthesis of unidentified secondary metabolites. Considering the need for new drugs to treat a variety of diseases, further exploration of the myxobacteria is imperative. Tools for genetic manipulation of myxobacteria are important for identifying and engineering strains to maximize production of secondary metabolites. Several developments have enabled heterologous gene expression in myxobacteria, including the construction and development of regulated promoters and the identification of strong constitutive promoters. While most genetic tools were first developed for the model myxobacterium Myxococcus xanthus, many have been applied to Sorangium cellulosum, Stigmatella aurantiaca, and the lesser-known myxobacteria Chondromyces crocatus, Cystobacter fuscus, Angiococcus disciformis, and Corallococcus macrosporus. This chapter describes these tools and hopes to facilitate the increased use of myxobacteria for applications in biotechnology and drug discovery. Electroporation has become the most common technique to introduce DNA into myxobacteria, including the species M. xanthus, S. aurantiaca, C. fuscus, A. disciformis, and C. macrosporus. Mutagenesis is fundamental to any genetic manipulation. Transposon mutagenesis is critical for myxobacterial genetics due to the ease of mutation identification. Genetic mapping and linkage analysis may be performed using generalized transduction or genomic DNA transformation by electroporation in M. xanthus. Several systems have been used for regulated gene expression in M. xanthus. The tetR-tetA regulatory system from Escherichia coli was used recently to engineer another regulated promoter in M. xanthus.