the digestive tract and most intestinal infections but are not used to treat intestinal infections by one strain of these bacteria. The flagella which allow the bacteria to swim have a peritrichous arrangement. It also attaches and effaces to the microvilli of the intestines via an adhesion molecule known as intimin. Metabolism E. coli can live on a wide variety of substrates and uses mixed acid fermentation in anaerobic conditions, producing lactate, succinate, ethanol, acetate, and carbon dioxide. Since many pathways in mixed-acid fermentation produce hydrogen gas, these pathways require the levels of hydrogen to be low, as is the case when E. coli lives together with hydrogen-consuming organisms, such as methanogens or sulphate-reducing bacteria. In addition, E. colis metabolism can be rewired to solely use CO2 as the source of carbon for biomass production. In other words, this obligate heterotroph's metabolism can be altered to display autotrophic capabilities by heterologously expressing carbon fixation genes as well as formate dehydrogenase and conducting laboratory evolution experiments. This may be done by using formate to reduce electron carriers and supply the ATP required in anabolic pathways inside of these synthetic autotrophs. E. coli have three native glycolytic pathways: EMPP, EDP, and OPPP. The EMPP employs ten enzymatic steps to yield two pyruvates, two ATP, and two NADH per glucose molecule while OPPP serves as an oxidation route for NADPH synthesis. Although the EDP is the more thermodynamically favourable of the three pathways, E. coli do not use the EDP for glucose metabolism, relying mainly on the EMPP and the OPPP. The EDP mainly remains inactive except for during growth with gluconate. Catabolite repression When growing in the presence of a mixture of sugars, bacteria will often consume the sugars sequentially through a process known as 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