Forty-one bacterial strains isolated from the headbox water of two machines in a Canadian paper mill were associated with the genera Asticcacaulis, Acidovorax, Bacillus, Exiguobacterium, Hydrogenophaga, Pseudomonas, Pseudoxanthomonas, Staphylococcus, Stenotrophomonas based on the sequence of their 16S rRNA genes. The metabolic profile of these strains were determined using Biolog EcoPlate, and the bacteria were divided into four metabolic groups. Metabolic profiles of the bacterial communities colonizing the headbox water of two paper machines was also determined weekly over a 1 year period. The only compound that was not reduced by the bacterial community was 2-hydroxybenzoic acid. Utilization frequency of the other carbon sources in the Biolog EcoPlate ranged from 3 to 100%. The metabolic profiles of the bacterial community did not vary considerably between the two paper machines. However, the metabolic profile varied among the sampling dates.

The headbox water is the main source of bacterial contamination of paper machines. Identification of these bacterial contaminants could be an asset in developing specific control methods. An amplified ribosomal DNA restriction analysis (ARDRA) was carried out to characterize the bacterial communities associated with the headbox water of a paper machine in a Canadian mill in February and July 2006. Eight bacterial genera were identified as the main colonizers present in the headbox water. The genus Meiothermus appeared to be the dominant bacterial group in the Canadian paper machine. Some variation was observed between the February and July clone libraries. Bacterial genera such as Chelatococcus and Hydrogenophilus were only detected in February or in July, respectively. Furthermore, the proportion of Tepidimonas clones in the libraries was higher in July than in February. The metabolic profile of the February and July communities, determined using Biolog EcoPlates, also suggested that temporal variation occurred within the bacterial populations that colonized the headbox of the paper machine.