%0 Journal Article
%T H-NS controls metabolism and stress tolerance in Escherichia coli O157:H7 that influence mouse passage
%A Irfan Erol
%A Kwang-Cheol Jeong
%A David J Baumler
%A Boris Vykhodets
%A Sang Ho Choi
%A Charles W Kaspar
%J BMC Microbiology
%D 2006
%I BioMed Central
%R 10.1186/1471-2180-6-72
%X The hns mutant grew slower and was non-motile in comparison to the parent strain. Carbon and nitrogen metabolism was significantly altered in the hns mutant, which was incapable of utilizing 42 carbon, and 19 nitrogen sources that the parent strain metabolized. Among the non-metabolized substrates were several amino acids, organic acids, and key metabolic intermediates (i.e., pyruvate) that limit carbon acquisition and energy generation. Growth studies determined that the parent strain grew in LB containing 14 to 15% bile or bile salts, while the hns mutant grew in 6.5 and 9% of these compounds, respectively. Conversely, log-phase cells of the hns mutant were significantly (p < 0.05) more acid tolerant than the parent strain and hns mutant complemented with pSC0061. In mouse passage studies, the parent strain was recovered at a higher frequency (p < 0.01) than the hns mutant regardless of whether log- or stationary-phase phase cells were orally administered.These results demonstrate that H-NS is a powerful regulator of carbon and nitrogen metabolism as well as tolerance to bile salts. It is likely that the metabolic impairments and/or the reduced bile tolerance of the E. coli O157:H7 hns mutant decreased its ability to survive passage through mice. Collectively, these results expand the influence of H-NS on carbon and nitrogen metabolism and highlight its role in the ability of O157:H7 strains to respond to changing nutrients and conditions encountered in the environment and its hosts.Escherichia coli O157:H7 is a human pathogen that causes hemorrhagic colitis in humans and in some cases may incite hemolytic uremic syndrome [1]. Cattle are a principal reservoir and contaminated ground beef is most frequently implicated in foodborne outbreaks associated with this human pathogen [2,3]. Adult cattle harboring serotype O157:H7 strains are asymptomatic, and the numbers and duration of shedding are influenced by a number of factors including feed, the microbial compositio
%U http://www.biomedcentral.com/1471-2180/6/72