SUMMARY: Increase in the production of the fimbrial adhesin K99 by enterotoxigenic in continuous cultures at specific growth rates above 0·25 hwas shown to be independent of the nature of the growth-limiting nutrient. The correlation between specific growth rate and K99 production was also found to be independent of the copy number of the K99 operon. Introduction of additional copies of the K99 regulatory region did not affect growth-ratedependent K99 production in wild-type strains, indicating that no hypothetical regulatory host factor is titrated by the K99 regulatory region. Regulation at the transcriptional level was measured with galactokinase gene fusions. The transcription of the fimbrial subunit gene increased with an increase in specific growth rate. This growth-ratedependent transcription was found to originate from the strong promoter P. Transcription originating from the weaker promoter P was independent of growth rate. The results indicated that transcriptional regulation at P is involved in the growth-rate-dependent regulation of K99 production.


Article metrics loading...

Loading full text...

Full text loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error