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Colored moderately thermophilic bacteria in paper-machine biofilms
M Kolari1, J Nuutinen, F A Rainey
1Department of Applied Chemistry and Microbiology, University of Helsinki, PO Box 56 (Biocenter), 00014, Helsinki, Finland. marko.kolari@helsinki.fi
Journal of Industrial Microbiology & Biotechnology
|April 18, 2003
Summary
Colored biofilms in paper machines are often caused by thermophilic bacteria like Deinococcus geothermalis and Meiothermus silvanus. Some biocides may unexpectedly increase biofilm formation by these paper-making microbes.
Area of Science:
- Microbiology
- Industrial Microbiology
- Paper Manufacturing Science
Background:
- Biofilms, particularly colored slimes, pose significant operational challenges in paper and board manufacturing.
- Understanding the microbial diversity and behavior within these biofilms is crucial for effective control strategies.
Purpose of the Study:
- To conduct a microbiological survey of colored biofilms in paper machines.
- To identify the bacterial strains responsible for colored slime outbreaks.
- To investigate the thermophilic nature and biofilm-forming potential of isolated bacteria, as well as their susceptibility to biocides.
Main Methods:
- Microbiological survey of six paper and board machines, including isolation and characterization of pigmented bacterial strains.
- Thermophilic growth analysis at different temperatures (28°C, 52°C, 56°C).
- Microtiter plate assays to assess biofilm formation potential and biocide susceptibility (methylene bisthiocyanate, 2,2-dibromo-3-nitrilopropionamide).
- Bacterial identification using established taxonomic methods.
Main Results:
- Isolated 95 pigmented bacterial strains, predominantly moderately thermophilic (99% grew at 52°C).
- Identified common primary biofilm-formers: pink-pigmented Deinococcus geothermalis and red-pigmented Meiothermus silvanus.
- Observed that certain biocide concentrations (5 ppm) could promote biofilm formation in 39 strains, suggesting potential biocide inactivation by high cell densities.
- Described four distinct groups of colored bacteria, including a novel genus of alpha-Proteobacteria, with some species previously known from hot spring microbial mats.
Conclusions:
- Deinococcus geothermalis and Meiothermus silvanus are key players in pink and red slime formation in paper machines, respectively.
- The study highlights the potential for biocides to inadvertently enhance biofouling under specific conditions.
- This research provides valuable data for recognizing and managing colored slime outbreaks in the paper industry, identifying novel bacterial contributors.