Bacterial growth and biofilm production on pyrene

Enrichment cultures inoculated with Arctic soil yielded a biofilm that grew on pyrene and phenanthrene. In a 60-day period, the biofilm degraded 20 microg ml(-1) pyrene or 39 microg ml(-1) phenanthrene. Single colonized pyrene crystals (approximately 1.5x0.75x0.35 mm) yielded 10(11) culturable heterotrophs and 10(5) biofilm propagules. Analysis of ribosomal intergenic spacers identified six phylotypes in a clone library from the pyrene biofilm. Analysis of 16S rRNA gene sequences indicated that the phylotypes, in order of decreasing abundance, are most closely related to members of the genera Polaromonas, Sphingomonas, Alcaligenes, Caulobacter and Variovorax. Two isolates capable of growth on pyrene, both Pseudomonas spp., were obtained from the pyrene enrichment culture. Growth of microbial biofilms on polycyclic aromatic hydrocarbons has not been reported previously, and this mode of growth may have important effects on substrate uptake.