초록
<P><B>ABSTRACT</B><P> During fermentation of sugars, a number of bacterial species are able to switch from mixed acid production to acetoin and 2,3-butanediol production in order to avoid lethal acidification of their environment, although the regulation of this switch is only poorly understood. In this study, we report the identification of the <I>budAB</I> structural operon, involved in acetoin production in Serratia plymuthica RVH1, and its activation by a LysR-type regulator encoded by <I>budR</I> , immediately upstream of this operon. In addition, the regulation of <I>budR</I> transcription was elucidated and found to be subject to negative control by BudR itself and to positive control by external stimuli such as <I>N</I> -(3-oxohexanoyl)- l -homoserine lactone (OHHL) quorum sensing signaling molecules and acetate. Interestingly, however, we observed that induction of <I>budR</I> transcription by OHHL or acetate did not require BudR, indicating the involvement of additional regulatory factors in relaying these environmental signals to the <I>budR</I> promoter. </P></P>