The integration of genes into methylobacterium, such as M. extorquens ATCC is disclosed, using a transposon system, preferably the mini-Tn7 transposon system, and under the control of a promoter, such as the strong methanol dehydrogenase promoter (P.sub.mxaF). Multicopy integration of genes of interest is also disclosed. The unique and specific attachment site for the Tn7 attachment (attTn7) is identified for M. extorquens.