ABSTRACT
Biological slimes (biofilms) collected from the wet end of paper and board machines were examined by electron microscopy and analyzed for fatty acid composition, neutral sugar composition, and ATP. Electron microscopy revealed minuscule prokaryotic organisms (diameter, 0.2 to 0.4 μm). Larger cells morphologically resembling Sphaerotilus and Leptothrix spp. were found in slimes from machines using recycled fiber or unbleached pulp. The bacteria were embedded in a slimy matrix and often contained reserve materials microscopically resembling poly-β-hydroxybutyrate and glycogen. Fatty acid analysis of the slimes revealed bacterial signature fatty acids in concentrations equivalent to the presence of 2 × 1010 to 2.6 × 1012 (average, 7 × 1011) bacterial cells (live and dead) per g (dry weight) of slime. The slimes contained several known components of bacterial polysaccharides in addition to glucose, indicating that the slime body consisted of bacterial polysaccharides. The slimes contained uronic acids equivalent to a binding capacity of 12.5 to 50 μmol of divalent cations per g (dry weight) of slime. The uronic acid-containing polysaccharides may be responsible for the accumulation of heavy metals in the slime. Calculation of the ATP contents of the slimes resulted in an estimate of 5 × 1012 cells per g (dry weight) of slime when calibrated with pure bacterial cultures isolated from the slimes. From electron micrographs, an estimate ranging from 1 × 1010 to 1.5 × 1012 (average, 4 × 1011) cells per g (dry weight) of slime was obtained.
FOOTNOTES
↵* Corresponding author. Mailing address: Department of General Microbiology, P.O. Box 41 (Mannerheimintie 172), FIN-00014 University of Helsinki, Finland. Phone: 358-0-4735 404. Fax: 358-0-4735 426.
- Copyright © 1994, American Society for Microbiology