Colored moderately thermophilic bacteria in paper-machine biofilms

Abstract

Biofilms cause several problems in papermaking. This report describes a microbiological survey of colored biofilms in six paper and board machines, including two case studies of outbreaks of colored slimes in which the causative bacteria were found. A total of 95 pink-, red-, orange- or yellow-pigmented strains were isolated. Nearly all (99%) of the strains grew at 52 degrees C, 72% grew at 56 degrees C, but only 30% grew at 28 degrees C, indicating that most of the strains were moderately thermophilic. Biofilm formation potential and biocide susceptibility of the strains were analyzed with a microtiter plate assay. In the presence of 5 ppm of methylene bisthiocyanate or 2,2-dibromo-3-nitrilopropionamide in paper-machine water, 55 strains formed biofims. Moreover, 39 strains increased biofilm production by 5-753% in the presence of biocide, suggesting that biocide concentrations inhibitory to planktonic but not to surface-attached cells may actually promote biofouling. The cells may have inactivated a portion of the biocides, as the cell density in this assay was high, corresponding to the highest cell densities occurring in the circulating waters. Four groups of colored bacteria that were isolated from several mills were identified. Pink-pigmented Deinococcus geothermalis and red-pigmented Meiothermus silvanus occurred as common primary biofilm-formers in paper machines. This report is the first description of the involvement of Meiothermus species in red-slime formation in the paper industry. The third group of bacteria (putative new species related to Roseomonas) contained strains that were not biofilm formers, but which were commonly found in slimes of neutral or alkaline machines. The fourth group contained red-pigmented biofilm-forming strains representing a novel genus of alpha- Proteobacteria related to Rhodobacter. Many colored paper-machine bacteria are species previously known from microbial mats of hot springs. Some characteristics of the bacterial groups are described here in order to facilitate their recognition in future cases of colored-slime outbreaks in the paper industry.

Physiology of Resistant Deinococcus geothermalis Bacterium Aerobically Cultivated in Low-Manganese Medium

“…geothermalis has found an industrial niche in paper industry, where it forms biofilms on warm air-exposed splash surfaces (33,35,44,45,58), showing that this species is able to fight oxidative stress caused by aerobic lifestyle and by oxidizing biocides. The genome of D. geothermalis was sequenced (42), but it did not reveal unique defense systems which could be responsible for the extreme resistance of this species, and thus the molecular background of the D. geothermalis resistance remains unclear.…”

Bacterial Community Characterization in Paper Mill White Water

“…The majority of available studies have adopted culture-dependent techniques (Desjardins and Beaulieu 2003, Kolari 2003, Kolari et al 2003, Suihko et al 2004, Suihko and Skyttä 2009, thus underestimating the microbial diversity of the original sample. In this study, both culture-dependent and independent approaches were applied in order to i) maximize the amount of information that could be retrieved on bacterial community composition, and ii) gain criteria on which of the two approaches should be chosen to obtain the best insights into bacterial community dynamics in this specific industrial environment.…”

“…These results suggest that most microorganisms belonging to Gammaproteobacteria and Betaproteobacteria subclasses, that are present in paper making, could be cultivable. Many of them have also been previously isolated from paper machines with culturedependent techniques (Desjardins & Beaulieu 2003, Kolari 2003, Kolari et al 2003, Suihko et al 2004, Suihko and Skyttä 2009. Some bacterial groups were only detected by library construction (phyla Deinococcus-Thermus and Spirocheates; subclasses Deltaproteobacteria and Alphapro-teobacteria) representing just the 14% of total screened clones.…”

“…(Kanto Öqvist 2008;Blanco et al 1996;Väisänen et al 1998;Ekman 2011;Peltola 2011). Once microorganisms enter the process, some of them find optimal conditions to proliferate: temperatures ranging from 37 °C to 60 °C, pH ranging from 5 to 10 (Ekman 2011), and the presence of cellulose and organic compounds, which provide abundant sources of nutrients (Blanco et al 1996, Salzburger 1996, Väisänen et al 1998, Raaska et al 2002, Kolari et al 2003, Kolari 2007Kanto Öqvist et al 2008). In this context, the paper mill becomes an effective incubator, and recycled water becomes a source of bacterial contaminants as important as external sources are.…”

“…The slimy biological deposits can also affect the quality of the end product because they can be detached from surfaces and can cause paper web breaks, or colored spots in the produced paper (Sanborn 1965;Väisänen et al 1994;Blanco et al 1996;Chaundhary et al 1997;Lindberg et al 2001;Pauly, 2002;Desjardins and Beaulieu 2003;Kolari 2003;Rättö et al 2005). Earlier studies have demonstrated that more than 60% of end-product defects are caused by holes or deposits on the paper surface, in which bacterial DNA has been detected (Haapala et al 2010).…”