Catabolic versatility of aromatic compound-degrading halophilic bacteria

There is growing interest in the development and optimization of bioremediation processes to deal with environments with high salinity that are contaminated with aromatic compounds. To estimate the diversity of moderately halophilic bacteria that could be used in such processes, enrichments were performed based on growth with a variety of aromatic compounds including phenol as a model pollutant. A group of bacteria that were able to grow over a wide range of salt concentrations were isolated, with the majority of these assigned to the genus Halomonas using phenotypic features and 16S rRNA sequences comparison. PCR amplification with degenerate primers revealed the presence in these isolates of genes encoding ring-cleaving enzymes in the beta-ketoadipate pathway for aromatic catabolism: catechol 1,2-dioxygenase and protocatechuate 3,4-dioxygenase. Furthermore, the activity of these two enzymes was detected in the newly described species Halomonas organivorans. Together, these studies indicate that moderately halophilic bacteria have the potential to catabolize aromatic compounds in environments with high salinity.