Search

Biofilms can cause severe problems in industrial paper mills, particularly of economic and technological types (clogging of filters, sheet breaks or holes in the paper, machine breakdowns, etc.). We present here some promising results on the use of essential oil compounds to control these biofilms. Biofilms were grown on stainless-steel coupons with a microbial white water consortium sampled from an industrial paper mill. Five essential oil compounds were screened initially in the laboratory in terms of their antimicrobial activity against planktonic cells and biofilms. The three most active compounds were selected and then tested in different combinations. The combination finally selected was tested at the pilot scale to confirm its efficiency under realistic conditions. All the compounds tested were as active against biofilms as they were against planktonic cells. The most active compounds were thymol, carvacrol, and eugenol, and the most efficient combination was thymol–carvacrol. At a pilot scale, with six injections a day, 10 mM carvacrol alone prevented biocontamination for at least 10 days, and a 1 mM thymol–carvacrol combination enabled a 67 % reduction in biofilm dry matter after 11 days. The use of green antimicrobials could constitute a very promising alternative or supplement to the treatments currently applied to limit biofilm formation in the environment of paper mill machines.

International audience; During the process of papermaking by pulp and paper plants, a thick and viscous deposits, termed slime, is quickly formed around the paper machines, which can affect the papermaking process. In this study, we explored the composition of the bacterial biota in slime that developed on shower pipes from 2 machines at a Canadian paper mill. Firstly, the composition was assessed for 12 months by DNA profiling with polymerase chain reaction coupled with denaturing gradient gel electrophoresis. Except for short periods (2-3 months), clustered analyses showed that the bacterial composition of the slime varied substantially over the year, with less than 50% similarity between the denaturing gradient gel electrophoresis profiles. Secondly, the screening of 16S rRNA gene libraries derived from 2 slime samples showed that the most abundant bacteria were related to 6 lineages, including Chloroflexi, candidate division OP10, Clostridiales, Bacillales, Burkholderiales, and the genus Deinococcus. Finally, the proportion of 8 bacterial lineages, such as Deinococcus sp., Meiothermus sp., and Chloroflexi, was determined by the Catalyzed Reporter Deposition-Fluorescence In Situ Hybridization in 2 slime samples. The results showed a high proportion of Chloroflexi, Tepidimonas spp., and Schlegelella spp. in the slime samples.