Metabolic Regulation in the Actinomycete Amycolatopsis Methanolica, a Facultative Methylotroph Employing the Rump Cycle for Formaldehyde Assimilation

Abstract

Facultative methylotrophs can be found abundantly among organisms employing the Calvin cycle, the serine pathway, or the XuMP cycle for the assimilation of C1 compounds. It is only in recent years, however, that we have succeeded in the isolation of a number of versatile RuMP cycle bacteria. These facultative RuMP cycle methylotrophs are found almost exclusively among Gram-positive bacteria. Representatives are various bacilli, coryneform bacteria, and actinomycete species (Dijkhuizen et al, 1992; Dijkhuizen, 1993). Most of these organisms grow on methylated amines and only few use methanol as sole carbon- and energy source for growth. Currently we are engaged in a detailed physiological, biochemical and genetic analysis of pathways of primary metabolism in the actinomycete Amycolatopsis methanolica. This Gram-positive bacterium is a very versatile methanol-utilizing organism, employing the fructose- bisphosphate aldolase cleavage variant of the RuMP cycle of formaldehyde fixation (Hazeu et al., 1983; de Boer et al., 1990a). In the following sections our studies on metabolic regulation in A. methanolica are reviewed with emphasis on glucose and methanol metabolism, the biosynthesis of aromatic amino acids, and the development of gene cloning systems for this organism.