title: Effect of sulfur sources on specific desulfurization activity of Rhodococcus erythropolis KA2-5-1 in exponential fed-batch culture.
abstract: The effects of sulfur sources on the desulfurization activity of Rhodococcus erythropolis KA2-5-1 were investigated by using an exponential fed-batch culture technique. The feed rate of a sulfur source was controlled independently of the feed rate of ethanol, which was used as a carbon and energy source. Among the sulfur sources examined were dibenzothiophene (DBT), ammonium sulfate, L-cysteine, L-methionine, and 2-amino-ethanesulfonic acid. When the fed-medium contained DBT as the sole sulfur source, KA2-5-1 cells showed a maximum desulfurization activity of approximately 130 mmol 2-HBP kg-cell(-1) h(-1). Similar levels of enzyme activity were also achieved with inexpensive ammonium sulfate by using the exponential fed-batch culture technique. In addition, higher levels of desulfurization activity were achieved by increasing the dosage of the DBT desulfurization (dsz) operon and dszD gene in R. erythropolis KA2-5-1. The recombinant strain showed a maximum desulfurization activity of approximately 250 mmol 2-HBP kg-cell(-1) h(-1) in the exponential fed-batch cultures.
authors.affiliation: Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Konishi
authors.forename: Michimasa
authors.initials: M
authors.lastname: Kishimoto
authors.forename: Takeshi
authors.initials: T
authors.lastname: Omasa
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Katakura
authors.forename: Suteaki
authors.initials: S
authors.lastname: Shioya
authors.forename: Hisao
authors.initials: H
authors.lastname: Ohtake
mesh_terms: D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology*; D018929:Cell Culture Techniques / Q000379:methods*; D000431:Ethanol / Q000378:metabolism*; D012240:Rhodococcus / Q000145:classification / Q000254:growth & development* / Q000378:metabolism*; D013457:Sulfur Compounds / Q000378:metabolism*
chemical_list: D013457:Sulfur Compounds; D000431:Ethanol