Dibutyl phthalate degrading bacteria isolated from the rhizosphere of bluegrass (Poa pratensis L.)

The ability of three bacterial strains of the class Actinomycetes, isolated from the rhizosphere of bluegrass (Poa pratensis L.) plants growing in the industrial development area of the Verkhnekamsk salt deposit (Perm krai), to grow on dibutyl phthalate (DBP) as the only source of carbon and energy was studied. Based on 16S rRNA gene analysis, it was shown that the strain Rh7bel showed similarity at 100% level with Rhodococcus wratislaviensis NBRC 100605T, and strains NKDBFbel and NKDBFgelt are phylogenetically close to two type strains of the species Pseudarthrobacter oxydans and Pseudarthrobacter polychromogenes (99.83% similarity). DBP-degrading strains are characterized by efficient growth on the key metabolite of DBP degradation, orthophthalic acid, and utilization of this metabolite. The strain Rhodococcus sp. Rh7bel demonstrated the highest rates of DBP utilization: the maximum specific substrate consumption rate was 0.018±0.002 h-1, substrate utilization was 70.7% in 72 hours (initial DBP concentration 0.2 g/L). Thus, rhizosphere DBP-degrading strains Rhodococcus sp. Rh7bel, Pseudarthrobacter spp. NKDBFbel and NKDBFgelt are promising for further study and development of technology for phytoremediation of soils contaminated with phthalates.