Effects of pulse feeding of beet molasses on recombinant benzaldehyde lyase production by Escherichia coli BL21(DE3).
The effect of fed-batch operation (FBO) strategy was investigated using pretreated-beet molasses, containing galactose that induces the lac promoter, on benzaldehyde lyase (BAL) production by recombinant Escherichia coli BL21(DE3)pLySs. After batch cultivation with 30 g l(-1) pretreated-beet molasses consisting of 7.5 g l(-1) glucose and 7.5 g l(-1) fructose, three FBO strategies were applied at dissolved oxygen (=40%) cascade to air-flow rate. In FBO1 when air-flow rate decreased considerably, feed was given to the system in pulses in such a way that pretreated-beet molasses concentration increased by 10 kg m(-3) (containing 2.5 g l(-1) glucose+2.5 g l(-1) fructose); however, decrease in air-flow rate demonstrated only the absence of glucose but not fructose. Thus, in FBO2 when fructose and glucose were completely utilized, pretreated-beet molasses was pulse-fed and its concentration increased by 10 g l(-1). In FBO3 with the decreased amount of pretreated-beet molasses (6 g l(-1)), shift response time from glucose to fructose consumption was avoided, and glucose and fructose consumptions were well correlated with air-flow rate, and the highest CX (8.04 g l(-1)) and BAL (2,315 U ml(-1)) production were obtained (t=24 h) with the highest substrate yield on cell and product formation.
Calik
Pinar
P
Department of Chemical Engineering, Industrial Biotechnology and Metabolic Engineering Laboratory, Middle East Technical University, 06531, Ankara, Turkey. pcalik@metu.edu.tr
Levent
Hande
H
D000446:Aldehyde-Lyases / Q000096:biosynthesis*; D019149:Bioreactors / Q000382:microbiology; D003470:Culture Media / Q000737:chemistry*; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000096:biosynthesis*; D005285:Fermentation; D008965:Molasses; D011994:Recombinant Proteins / Q000096:biosynthesis; D013549:Sweetening Agents / Q000378:metabolism*
D003470:Culture Media; D029968:Escherichia coli Proteins; D011994:Recombinant Proteins; D013549:Sweetening Agents; D000446:Aldehyde-Lyases; C059416:benzaldehyde lyase