Characterization of an 17β-estradiol-degrading bacterium Stenotrophomonas maltophilia SJTL3 tolerant to adverse environmental factors

Bioremediation of environmental estrogens requires microorganisms with stable degradation efficiency and great stress tolerance in complex environments. In this work, Stenotrophomonas maltophilia SJTL3 isolated from wastewater was found to be able to degrade over 90% of 10 μg/mL 17β-estradiol (E2) in a week and the degradation dynamic was fitted by the first-order kinetic equations. Estrone was the first and major intermediate of E2 biodegradation. Strain SJTL3 exhibited strong tolerance to several adverse conditions like extreme pH (3.0-11.0), high osmolality (2%), co-existing heavy metals (6.25 μg/mL of Cu²⁺) and surfactants (5 CMC of Tween 80), and retained normal cell vitality and stable E2-degradaing efficiency. In solid soil, strain SJTL3 could remove nearly 100% of 1 μg/mL of E2 after the bacteria inoculation and 8-day culture. As to the contamination of 10 μg/mL E2 in soil, the biodegradation efficiency was about 90%. The further obtainment of the whole genome of strain SJTL3 and genome analysis revealed that this strain contained not only the potential genes responsible for estrogen degradation, but also the genes encoding proteins involved in stress tolerance. This work could promote the estrogen-biodegrading mechanism study and provide insights into the bioremediation application.