title: Exopolymer diversity and the role of levan in Bacillus subtilis biofilms.
abstract: Exopolymeric substances (EPS) are important for biofilm formation and their chemical composition may influence biofilm properties. To explore these relationships the chemical composition of EPS from Bacillus subtilis NCIB 3610 biofilms grown in sucrose-rich (SYM) and sucrose-poor (MSgg and Czapek) media was studied. We observed marked differences in composition of EPS polymers isolated from all three biofilms or from spent media below the biofilms. The polysaccharide levan dominated the EPS of SYM grown biofilms, while EPS from biofilms grown in sucrose-poor media contained significant amounts of proteins and DNA in addition to polysaccharides. The EPS polymers differed also in size with very large polymers (Mw>2000 kDa) found only in biofilms, while small polymers (Mw<200 kD) dominated in the EPS isolated from spent media. Biofilms of the eps knockout were significantly thinner than those of the tasA knockout in all media. The biofilm defective phenotypes of tasA and eps mutants were, however, partially compensated in the sucrose-rich SYM medium. Sucrose supplementation of Czapek and MSgg media increased the thickness and stability of biofilms compared to non-supplemented controls. Since sucrose is essential for synthesis of levan and the presence of levan was confirmed in all biofilms grown in media containing sucrose, this study for the first time shows that levan, although not essential for biofilm formation, can be a structural and possibly stabilizing component of B. subtilis floating biofilms. In addition, we propose that this polysaccharide, when incorporated into the biofilm EPS, may also serve as a nutritional reserve.
authors: Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.
authors: Iztok
authors: I
authors: Dogsa
authors: Mojca
authors: M
authors: Brloznik
authors: David
authors: D
authors: Stopar
authors: Ines
authors: I
authors: Mandic-Mulec
mesh_terms: D001412:Bacillus subtilis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D001426:Bacterial Proteins / Q000302:isolation & purification; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D018533:Biomass; D001704:Biopolymers / Q000378:metabolism*; D002850:Chromatography, Gel; D003470:Culture Media / Q000494:pharmacology; D005630:Fructans / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D009696:Nucleic Acids / Q000302:isolation & purification; D009876:Operon / Q000235:genetics; D010641:Phenotype; D011135:Polysaccharides, Bacterial / Q000302:isolation & purification; D013395:Sucrose / Q000494:pharmacology; D013997:Time Factors
chemical_list: D001426:Bacterial Proteins; D001704:Biopolymers; D003470:Culture Media; D005630:Fructans; D009696:Nucleic Acids; D011135:Polysaccharides, Bacterial; D013395:Sucrose; C072599:levan
references: J Microbiol Methods. 2003 Jan;52(1):69-73
references: 12401228
references: Anal Biochem. 1976 May 7;72:248-54
references: 942051
references: Mol Microbiol. 2012 Jul;85(1):51-66
references: 22571672
references: J Bacteriol. 1995 Dec;177(23):6919-27
references: 7592486
references: mBio. 2012 Aug 14;3(4):e00184-12
references: 22893383
references: Environ Sci Technol. 2010 Dec 1;44(23):8964-70
references: 21033741
references: Proc Natl Acad Sci U S A. 2010 Feb 2;107(5):2230-4
references: 20080671
references: Plant Physiol. 2004 Jan;134(1):307-19
references: 14684838
references: Microbiology (Reading). 2001 Dec;147(Pt 12):3413-9
references: 11739774
references: Environ Microbiol. 2013 Mar;15(3):848-864
references: 22934631
references: J Bacteriol. 1986 Oct;168(1):380-8
references: 2428811
references: Methods Enzymol. 1990;182:50-68
references: 2314256
references: Mol Gen Genet. 1972;118(2):135-60
references: 4628133
references: Mol Microbiol. 2001 Dec;42(5):1199-209
references: 11886552
references: J Dent Res. 1996 Aug;75(8):1572-7
references: 8906125
references: Biotechniques. 1995 Jan;18(1):62-3
references: 7702855
references: Mol Microbiol. 2011 Jun;80(5):1155-68
references: 21477127
references: Mol Microbiol. 2012 Aug;85(3):418-30
references: 22716461
references: J Agric Food Chem. 2005 Oct 19;53(21):8211-5
references: 16218666
references: Cytometry. 2001 Aug 1;44(4):309-16
references: 11500847
references: Mol Microbiol. 2011 Jun;80(5):1133-6
references: 21488983
references: J Bacteriol. 1984 Oct;160(1):438-41
references: 6148336
references: Mol Microbiol. 2012 Jul;85(1):8-11
references: 22607588
references: Mol Microbiol. 2008 Jan;67(2):254-63
references: 18047568
references: Nat Struct Biol. 2003 Nov;10(11):935-41
references: 14517548
references: Trends Microbiol. 2005 Jan;13(1):20-6
references: 15639628
references: Microbiology (Reading). 2001 Jan;147(Pt 1):3-9
references: 11160795
references: Water Res. 2012 Oct 1;46(15):4803-13
references: 22776210
references: Appl Environ Microbiol. 2009 May;75(9):2861-8
references: 19251901
references: Proc Natl Acad Sci U S A. 2001 Sep 25;98(20):11621-6
references: 11572999
references: J Bacteriol. 2011 Sep;193(18):4821-31
references: 21742882
references: Microbiology (Reading). 2006 Sep;152(Pt 9):2801-2807
references: 16946274
references: Science. 2002 Feb 22;295(5559):1487
references: 11859186
references: J Bacteriol. 1999 Mar;181(5):1664-72
references: 10049401
references: Res Microbiol. 1991 Sep-Oct;142(7-8):757-64
references: 1784813
references: J Bacteriol. 2004 Jun;186(12):3970-9
references: 15175311
references: Biomacromolecules. 2004 Jul-Aug;5(4):1219-30
references: 15244434
references: Nat Rev Microbiol. 2010 Sep;8(9):623-33
references: 20676145
references: Microbiology (Reading). 2006 Oct;152(Pt 10):2909-2918
references: 17005972
references: Mol Microbiol. 2005 Feb;55(3):739-49
references: 15661000
references: Environ Microbiol. 2012 Jun;14(6):1378-89
references: 22390407
references: Biophys J. 2005 Oct;89(4):2711-20
references: 16085763
references: J Biotechnol. 2002 May 23;95(3):249-56
references: 12007865
references: J Hazard Mater. 2008 Jun 15;154(1-3):1120-6
references: 18162303
references: Int Microbiol. 2006 Mar;9(1):21-8
references: 16636986
references: Mol Microbiol. 2006 Feb;59(4):1229-38
references: 16430696
references: Biosci Biotechnol Biochem. 2002 Jul;66(7):1555-8
references: 12224641
references: J Bacteriol. 2007 Jul;189(13):4920-31
references: 17468240
references: Trends Microbiol. 2001 May;9(5):222-7
references: 11336839
references: FEMS Microbiol Lett. 2010 Dec;313(1):1-9
references: 20735481
references: Mol Microbiol. 2005 Aug;57(4):1143-58
references: 16091050
references: J Bacteriol. 2009 Mar;191(6):1756-64
references: 19114482
references: Proc Natl Acad Sci U S A. 2009 Jan 6;106(1):280-5
references: 19114652