Surrogate genetics: The use of bacterial hybrids as a genetic tool

Experimental dissection of bacterial genomes requires a well-developed set of genetic tools, but many bacteria lack the essential tools required for g enetic analysis. Recombination of a region of chromosomal DNA from poorly c haracterized donor bacteria with the chromosome of a suitable surrogate hos t creates a genetically malleable hybrid, providing a shortcut for the deta iled genetic analysis of the substituted genes. However, recombination betw een closely related but nonidentical DNA sequences ("homeologous recombinat ion") is strongly inhibited, posing a powerful barrier to gene exchange bet ween bacteria and a major impediment to the construction of genetic hybrids . By taking advantage of mutS and recD mutant recipients, it is possible to effectively overcome the recombination barrier, allowing construction of g enetic hybrids in a related surrogate host. Once stably recombined into the recipient chromosome, the donor DNA can be studied with all the genetic to ols available in the surrogate host. In addition to facilitating standard g enetic analysis, use of a surrogate host can provide novel approaches to st udy the physiological roles of unique genes from poorly characterized bacte ria. (C) 2000 Academic Press.