|
Full Length Research Paper
|
|
Optimization of
biomass-producing conditions of Micrococcus sp. S-11
for L-cysteine production
Tao Dong1, Lin Zhao1, 2*, Yu Huang2,
Xin Tan1, 2
1School
of Chemical Engineering and Technology, Tian Jin University,
Tianjin 300072, PR China.
2School
of Environment Science and Technology, Tian Jin University,
Tianjin 300072, PR China.
*Corresponding author. E-mail:
zhaolin@tju.edu.cn
or
tjudongtao@tju.edu.cn. Tel.: +86 22 27405495. Fax: +86
22 27890259.
Accepted
23 March, 2009 |
|
|
|
Abstract |
|
|
|
Micrococcus
S-11 isolated from sediments could transform racemic
2-Amino-D2-thiazoline-4-carboxylic
acid (ATC) into L-cysteine. The optimal carbon and nitrogen
source for its biomass production were glucose and urea. The
optimal culture conditions for biomass production were
investigated through statistical experiment design and data
analysis. A screening test was first conducted on ten
process variables using a Plackett–Burman design, from which
three parameters including glucose, urea and rotational
speed were chosen as significant ones influencing biomass
production. Then these three variables were optimized by
Box-behnken experimental design and response surface
methodology, and a multinomial equation was constructed to
describe the correlation between the biomass production and
the three tested variables. By solving to this equation, the
predicted maximum biomass was obtained at 11.30 g/L when the
culture conditions were glucose 21.98 g/L, urea 4.75 g/L and
rotational speed 124 rpm. The validation experiments were
carried out under the optimal conditions, from which the
average biomass obtained was 11.26 g/L close to the
predicted biomass (11.30 g/L), which was 80.7% higher than
the one 6.23 g/L obtained under the initial conditions. The
results from validation experiments verified the accuracy of
the model in terms of depicting the biomass production of
Micrococcus sp. S-11.
Key
words:
L-cysteine, 2-Amino-D2-thiazoline-4-carboxylic
acid (ATC), biomass, Plackett-Burman design, Box-behnken
design, response surface methodology. |
|
