Submitted to: Applied Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 25, 2008
Publication Date: February 27, 2008
Citation: Leathers, T.D., Cote, G.L. 2008. Biofilm formation by exopolysaccharide mutants of Leuconostoc mesenteroides strain NRRL B-1355. Applied Microbiology and Biotechnology. 78(6):1025-1031. Interpretive Summary: Fundamental information is needed on how biofilms form. We examined the effect of polysaccharide mutations on the ability of a bacterium to form biofilms. Mutants formed biofilms under laboratory conditions, however the mutations greatly affected the appearance of the biofilms. Results will be of interest to researchers developing new strategies to control biofilm contaminations in agricultural processing industries.
Technical Abstract: Leuconostoc mesenteroides strain NRRL B-1355 produces the soluble exopolysaccharides alternan and dextran in planktonic cultures. A set of mutants of this strain are available that are deficient in the production of alternan, dextran, or both. Another mutant of NRRL B-1355, strain R1510, produces an insoluble glucan in place of alternan and dextran. To test the effect of exopolysaccharide production on biofilm formation, these strains were cultured in a biofilm reactor. All strains grew well as biofilms, with comparable cell densities, including strain NRRL B-21414, which produces neither alternan nor dextran in planktonic cultures. However, the exopolysaccharide phenotype clearly affected the appearance of the biofilms and the sloughed-off biofilm material produced by these biofilms. For all strains, soluble glucansucrases and soluble polysaccharides produced by biofilm cultures appeared to be similar to those produced by planktonic cultures. Biofilms from all strains also contained insoluble polysaccharides. Strain R1510 biofilms contained an insoluble polysaccharide similar to that produced by planktonic cultures. For most other strains, the insoluble biofilm polysaccharides resembled a mixture of alternan and dextran.