Identification of aerobic mesophilic bacilli isolated from board and paper products containing recycled fibres

AIMS: To identify aerobic mesophilic bacteria isolated from coreboard, kitchen roll paper and food packaging boards containing recycled fibres and to create a rapid fingerprint-based database for their identification. METHODS AND RESULTS: A total of 197 isolates and 20 relevant type strains were characterized by automated ribotyping and as far as possible identified by the similarities of their riboprints to the relevant type strains. One strain from each unidentified ribotype, a total of 87 strains, was subjected to partial 16S rDNA sequencing and in most cases also to fatty acid analysis and physiological tests. From the isolates 113 and seven different ribotypes were generated belonging to the genera Bacillus and Paenibacillus, respectively. The dominating species, or closest related to them, were B. simplex (22.8% of isolates), B. licheniformis (18.3%) and B. amyloliquefaciens (12.7%); 5.1% of the isolates were identified as B. cereus, a potential food-borne pathogen. In particular, this species was present in one food packaging board (26.3% of isolates). Based on these results, 40.1% of the isolates and 45.0% of ribotypes were so different from the relevant type strains that they may represent novel species. CONCLUSIONS: All isolates were aerobic spore-formers, indicating that all non-spore-formers were eliminated during the drying stage of the processes. Although many isolates could be affiliated to described species of Bacillus or Paenibacillus, a significant proportion of the isolates could not be identified unambiguously as members of a described species. SIGNIFICANCE AND IMPACT OF THE STUDY: A RiboPrint identification database, composed of 120 composite patters, was established for bacteria originating from the pulp and paper industry. Considering the discrimination power of ribotyping, this database will be extremely useful in future for the reliable and rapid identification of bacteria isolated from pulp and paper industrial sources.