돌연변이 균주 Gordona sp. EID의 dibenzothiophene 탈황 특성

Characteristics of dibenzothiophene desulfurization by mutant Gordona sp. EID

석유탈황용 균주인 Gordona sp. CYKS1을 ethylmethanesulfone 처리하여 돌연변이 균주 EID를 개발하여, dibenzothiophene(DBT) 탈황 특성을 조사하였다. EID 균주는 DBT를 2-hydroxybiphenyl(2-HBP)와 sulfate로 대사하는 4S pathway를 가지며, wild type인 CYKS1이 $2.6{\mu}mol{\cdot}L^{-1}{\cdot}h^{-1}$의 탈황속도를 보이는 반면, EID균주는 $4.0{\mu}mol{\cdot}L^{-1}{\cdot}h^{-1}$의 탈황속도를 나타내었다. 탄소원으로 공급된 glucose의 농도가 EID 균주의 DBT탈황속도에 미치는 영향을 조사한 결과 glucose의 농도가 증가할수록 탈황속도가 증가하였다. 또한, DBT 분해속도에 미치는 DBT의 초기 농도의 영향을 알아본 결과, 2.0 mM에서 최대 DBT 분해활성($11.1{\mu}mol{\cdot}L^{-1}{\cdot}h^{-1}$)을 나타내었다. 최종 대사산물인 2-HBP와 sulfate 농도가 증가할수록 EID 균주의 DBT 분해능은 감소하였다. 0.2 mM의 2-HBP를 첨가한 배지에서는 EID 균주의 성장과 DBT 탈황능은 완전 저해 받았다. Sulfate가 0.5g/L 첨가된 조건에서의 EID 균주의 DBT 탈황속도는 $1.4{\mu}mol{\cdot}L^{-1}{\cdot}h^{-1}$이었다.

Mutant strain EID was developed by treating Gordona sp. CYKS1 with ethylmethanesulfone, and the desulfurization characteristics of dibenzothiophene(DBT) by mutant EID was investigated. Strain EID desulfurized DBT to 2-hydroxybiphenyl (2-HBP) by 4S pathway. Desulfurization rate of the strain EID was $4.0{\mu}mol{\cdot}L^{-1}{\cdot}h^{-1}$, while that of the wild type CYKS1 was $2.6{\mu}mol{\cdot}L^{-1}{\cdot}h^{-1}$. The effect of glucose concentration supplied as the carbon source on the DBT desulfurization showed that DBT desulfurization rate was enhanced as the glucose concentration increased. Maximum DBT desulfurization rate was $11.1{\mu}mol{\cdot}L^{-1}{\cdot}h^{-1}$ at 2.0 mM DBT concentration. As end-products such as 2-HBP and sulfate concentrations increase, DBT desulfurization activity of the strain EID decreased. When 0.2 mM of 2-HBP was added in the medium, no growth and desulfurization activity was observed. When 0.5 g/L $Na_2SO_4$ was simultaneously supplied with DBT, DBT desulfurization rate was$1.4{\mu}mol{\cdot}L^{-1}{\cdot}h^{-1}$.