Konishi Masaaki, Kishimoto Michimasa, Omasa Takeshi, Katakura Yoshio, Shioya Suteaki, Ohtake Hisao
Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
J Biosci Bioeng. 2005 Mar;99(3):259-63. doi: 10.1263/jbb.99.259.
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.
采用指数流加分批培养技术，研究了硫源对红平红球菌KA2-5-1脱硫活性的影响。硫源的进料速率与用作碳源和能源的乙醇的进料速率独立控制。所研究的硫源包括二苯并噻吩（DBT）、硫酸铵、L-半胱氨酸、L-甲硫氨酸和2-氨基乙磺酸。当补料培养基含有DBT作为唯一硫源时，KA2-5-1细胞表现出约130 mmol 2-HBP kg细胞（-1）h（-1）的最大脱硫活性。通过指数流加分批培养技术，使用廉价的硫酸铵也能达到类似水平的酶活性。此外，通过增加红平红球菌KA2-5-1中DBT脱硫（dsz）操纵子和dszD基因的剂量，可实现更高水平的脱硫活性。在指数流加分批培养中，重组菌株表现出约250 mmol 2-HBP kg细胞（-1）h（-1）的最大脱硫活性。
