title: Dynamic responses of Bacteroides thetaiotaomicron during growth on glycan mixtures.
abstract: Bacteroides thetaiotaomicron (Bt) is a human colonic symbiont that degrades many different complex carbohydrates (glycans), the identities and amounts of which are likely to change frequently and abruptly from meal-to-meal. To understand how this organism reacts to dynamic growth conditions, we challenged it with a series of different glycan mixtures and measured responses involved in glycan catabolism. Our results demonstrate that individual Bt cells can simultaneously respond to multiple glycans and that responses to new glycans are extremely rapid. The presence of alternative carbohydrates does not alter response kinetics, but reduces expression of some glycan utilization genes as well as the cell's sensitivity to glycans that are present in lower concentration. Growth in a mixture containing 12 different glycans revealed that Bt preferentially uses some before others. This metabolic hierarchy is not changed by prior exposure to lower priority glycans because re-introducing high priority substrates late in culture re-initiates repression of genes involved in degrading those with lower priority. At least some carbohydrate prioritization effects occur at the level of monosaccharide recognition. Our results provide insight into how a bacterial glycan generalist modifies its responses in dynamic glycan environments and provide essential knowledge to interpret related metabolic behaviour in vivo.
authors: Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
authors: Theresa E
authors: TE
authors: Rogers
authors: Nicholas A
authors: NA
authors: Pudlo
authors: Nicole M
authors: NM
authors: Koropatkin
authors: Joshua S K
authors: JS
authors: Bell
authors: Monica
authors: M
authors: Moya Balasch
authors: Kevin
authors: K
authors: Jasker
authors: Eric C
authors: EC
authors: Martens
mesh_terms: D000222:Adaptation, Physiological; D001439:Bacteroides / Q000254:growth & development* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D053858:Metabolic Networks and Pathways; D011134:Polysaccharides / Q000378:metabolism*
chemical_list: D011134:Polysaccharides
references: Structure. 2008 Jul;16(7):1105-15
references: 18611383
references: Mol Microbiol. 2012 Aug;85(3):478-91
references: 22686399
references: Science. 2003 Mar 28;299(5615):2074-6
references: 12663928
references: Am J Clin Nutr. 1984 Feb;39(2):338-42
references: 6320630
references: J Bacteriol. 1997 Feb;179(3):643-9
references: 9006015
references: Proc Natl Acad Sci U S A. 2000 Jun 20;97(13):7639-44
references: 10852969
references: FEMS Microbiol Lett. 1994 Dec 15;124(3):355-9
references: 7851742
references: Science. 2005 Mar 25;307(5717):1955-9
references: 15790854
references: PLoS One. 2010 Nov 29;5(11):e15046
references: 21151493
references: J Bacteriol. 2005 Feb;187(3):890-901
references: 15659667
references: Cell Host Microbe. 2008 Nov 13;4(5):447-57
references: 18996345
references: Science. 2011 Jul 1;333(6038):101-4
references: 21596954
references: Sci Transl Med. 2009 Nov 11;1(6):6ra14
references: 20368178
references: J Biol Chem. 2009 Sep 11;284(37):24673-7
references: 19553672
references: Cell. 2010 Jun 25;141(7):1241-52
references: 20603004
references: J Bacteriol. 1996 Dec;178(24):7180-6
references: 8955400
references: J Biol Chem. 2012 Oct 5;287(41):34614-25
references: 22910908
references: PLoS Biol. 2011 Dec;9(12):e1001221
references: 22205877
references: J Biol Chem. 2009 Jul 3;284(27):18445-57
references: 19403529