Editing Escherichia coli (section)

==== Catabolite repression ====
When growing in the presence of a mixture of sugars, bacteria will often consume the sugars sequentially through a process known as [[Catabolism|catabolite]] repression. By repressing the expression of the genes involved in metabolizing the less preferred sugars, cells will usually first consume the sugar yielding the highest growth rate, followed by the sugar yielding the next highest growth rate, and so on. In doing so the cells ensure that their limited metabolic resources are being used to maximize the rate of growth. The well-used example of this with ''E. coli'' involves the growth of the bacterium on [[glucose]] and [[lactose]], where ''E. coli'' will consume [[glucose]] before [[lactose]]. Catabolite repression has also been observed in ''E. coli'' in the presence of other non-glucose sugars, such as [[arabinose]] and [[xylose]], [[sorbitol]], [[rhamnose]], and [[ribose]]. In ''E. coli'', glucose catabolite repression is regulated by the [[phosphotransferase system]], a multi-protein [[phosphorylation]] cascade that couples [[glucose uptake]] and [[metabolism]].<ref>{{cite journal | vauthors = Ammar EM, Wang X, Rao CV | title = Regulation of metabolism in ''Escherichia coli'' during growth on mixtures of the non-glucose sugars: arabinose, lactose, and xylose | journal = Scientific Reports | volume = 8 | issue = 1 | pages = 609 | date = January 2018 | pmid = 29330542 | pmc = 5766520 | doi = 10.1038/s41598-017-18704-0 | bibcode = 2018NatSR...8..609A }}</ref>