Abstract
Bacillus megaterium shows diauxic growth in minimal medium containing glucose and xylose. We have examined the influence of three elements that regulate xyl operon expression on diauxic growth and expression of a xylA-lacZ fusion. xylA is 13-fold repressed during growth on glucose. Induction occurs at the onset of the lag phase after glucose is consumed. Inactivation of xylR yields a two-fold increase in expression of xylA on glucose. Deletion of the catabolite responsive element (cre) has a more pronounced effect, reducing glucose repression from 13-fold in the wild type to about 2.5-fold. When xylR and cre are inactivated together a residual two-fold repression of xylA is found. Inactivation of xylR affects diauxic growth by shortening the lag phase from 70 to 40 min. In-frame deletion of ccpA results in the loss of diauxic growth, an increase in doubling time and simultaneous use of both sugars. In contrast, a strain with an inactivated cre site in xylA exhibits diauxic growth without an apparent lag phase on glucose and xylose, whereas fructose and xylose are consumed simultaneously.
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
Received: 27 July 1995 / Accepted: 19 October 1995
Rights and permissions
About this article
Cite this article
Schmiedel, D., Hillen, W. Contributions of XylR, CcpA and cre to diauxic growth of Bacillus megaterium and to xylose isomerase expression in the presence of glucose and xylose. Mol Gen Genet 250, 259–266 (1996). https://doi.org/10.1007/BF02174383
Issue Date:
DOI: https://doi.org/10.1007/BF02174383