Las degradation in a fluidized bed reactor and phylogenetic characterization of the biofilm

A fluidized bed reactor was used to study the degradation of the surfactant linear alkylbenzene sulfonate (LAS). The reactor was inoculated with anaerobic sludge and was fed with a synthetic substrate supplemented with LAS in increasing concentrations (8.2 to 45.8 mg l-1). The removal efficiency of 93% was obtained after 270 days of operation. Subsequently, 16S rRNA gene sequencing and phylogenetic analysis of the sample at the last stage of the reactor operation recovered 105 clones belonging to the domain Bacteria. These clones represented a variety of phyla with significant homology to Bacteroidetes (40%), Proteobacteria (42%), Verrucomicrobia (4%), Acidobacteria (3%), Firmicutes (2%), and Gemmatimonadetes (1%). A small fraction of the clones (8%) was not related to any phylum. Such phyla variety indicated the role of microbial consortia in degrading the surfactant LAS.