Genetics of carbon metabolism in methylotrophic bacteria.

The application of genetic techniques to the methylotrophic bacteria has greatly enhanced studies of these important organisms. Two methylotrophic systems have been studied in some detail, the serine cycle for formaldehyde assimilation and the methanol oxidation system. In both cases, genes have been cloned and mapped in Methylobacterium species (facultative serine cycle methanol-utilizers). In addition, methanol oxidation genes have been studied in an autotrophic methanol-utilizer (Paracoccus denitrificans) and three methanotrophs (Methylosporovibrio methanica, Methylomonas albus and Methylomonas sp. A4). Although much remains to be learned in these systems, it is becoming clear that the order of C1 genes has been conserved to some extent in methylotrophic bacteria, and that many C1 genes are loosely clustered on the chromosome. Operons appear to be rare, but some examples have been observed. The extension of genetic approaches to both the obligate and facultative methylotrophs holds much promise for the future in understanding and manipulating the activities of these bacteria.