RT Journal Article SR Electronic(1) A1 van der Woude, Marjan W. A1 Arts, Patricia A. A1 Bakker, Douwe A1 van Verseveld, Henk W. A1 de Graaf, Frits K.YR 1990 T1 Growth-rate-dependent synthesis of K99 fimbrial subunits is regulated at the level of transcription JF Microbiology, VO 136 IS 5 SP 897 OP 903 DO https://doi.org/10.1099/00221287-136-5-897 PB Microbiology Society, SN 1465-2080, AB Increase in the production of the fimbrial adhesin K99 by enterotoxigenic Escherichia coli in continuous cultures at specific growth rates above 0·25 h−1was 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 PA. Transcription originating from the weaker promoter PB was independent of growth rate. The results indicated that transcriptional regulation at PA is involved in the growth-rate-dependent regulation of K99 production., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-136-5-897