ABSTRACT
Plasmids have been identified in a variety of methylotrophs. The first description of plasmids in methylotrophs was made by Warner et al. in 1977. A class of mutant which has been particularly useful, and could have useful applications for methylotrophs, is the conditional lethal mutant. Isolation of mutants in methylotrophs is demonstrably less easy than is the case with the Enterobacteriaceae or the pseudomonads. Transposable elements carrying antibiotic resistance determinants can transpose from the plasmids carrying them to sites on bacterial chromosomes or onto other plasmids carried by the same bacterium. The demonstration of native plasmids in various methylotrophs means that there could be a similar interaction between such plasmids and IncP-1 plasmids. Development of the appropriate plasmid systems in methylotrophs could result in effective gene transfer techniques. The stability of plasmids carried by bacteria varies greatly, depending upon the growth environment and genetic features of the plasmid and the host.
