Biodegradation of dibutyl phthalate using Deinococcus spp. isolated from Lout desert of Iran

Phthalates are fatty liquids, which are colorless and odorless, with very low solubility in water; they are used as a plasticizer in most polymer products. Thesecompounds have gained attention due to their high levels of toxicity, carcinogenicity and the emergence of multiple diseases in humans and living organisms. In this study, dibutyl phthalate (DBP) biodegradation ability was investigated using Deinococcus spp. isolated from Lout desert of Iran. The strains LD4 and LD5 were inoculated into TSB medium and incubated at 30°C for 24 hours. Then 5 ml of growth medium was transferred to 100 ml of fresh minimal salt medium with 1 ml of sterile 7% DBP asa sole carbon source. The flasks were incubated on an orbital shaker at 30°C and 150 rpm for 24-48 hours. Biodegradation of DBP was investigated by two assessment methods including the optical density of growth culture using spectrophotometer (wavelength at 600 nm) and high-performance liquid chromatography (HPLC). The results demonstrated that both Deinococcus strains, LD4 and LD5, started degradation after 6 hours then reached to a maximum after 24 hours of incubation. The results of growth assessment in the culture medium containing DBP showed that optical density of growth medium was increased by both LD4 and LD5 from 0.211 to 0.751 and 0.226 to 0.763, respectively. The results of this research revealed that the native Deinococcus strains isolated from Lout desert are suitable for the degradation of phthalates in industrial wastewater and contaminated sites.

Keywords:

Dibutyl phthalate , Biodegradation , Deinococcus