Intergeneric Transfer of the Pullulanase Gene between Klebsiella aerogenes and Escherichia coli by In Vivo Genetic Manipulation

抄録

The pullulanase gene (pul) of Klebsiella aerogenes was transferred in vivo to Escherichia coli by using RP4: : Mu cts. The pul gene was expressed in E. coli, although the level ofpullulanase activity in E. coli was lower than that in K. aerogenes, and the Pul⁺ transconjugants were relatively unstable in an unselective medium. Production of pullulanase, which is used to makemaltose from starch, was induced in E. coli by pullulan, waxy maize amylopectin, soluble starch and maltose. Whenthe transconjugant cells of E. coli were grown with pullulan or maltose, most pullulanase was produced intracellularly, whereas K. aerogenes produced pullulanase extracellularly. Retransfer of the pul_k gene from E. coli to K. aerogenes by conjugation resulted in an increase of the production of extracellular pullulanase.