Effects of CaCl2 on viscosity of culture broth, and on activities of enzymes around the 2-oxoglutarate branch, in Bacillus subtilis CGMCC 2108 producing poly-(γ-glutamic acid).
CaCl(2) was used as a novel additive to enhance poly-(γ-glutamic acid) (γ-PGA) production by Bacillus subtilis strain CGMCC 2108. Addition of CaCl(2) to medium effectively reduced viscosity of culture broth, and increased consumption of extracellular glutamate by 11.4%, leading to γ-PGA yield of 9.07 g/l, compared to 7.88 g/l in control. CaCl(2) also increased activities of three key enzymes around the crucial 2-oxoglutarate branch of the γ-PGA biosynthesis pathway: isocitrate dehydrogenase (ICDH), glutamate dehydrogenase (GDH), and 2-oxoglutarate dehydrogenase complex (ODHC). In particular, GDH activity was increased more than 8-fold, indicating that more 2-oxoglutarate was directed to synthesis of glutamate, the substrate of γ-PGA. Interestingly, the molecular weight of γ-PGA remained constant regardless of CaCl(2) addition.
College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, PR China.
Baiqi
B
Huang
Peiyong
P
Qin
Zhiwen
Z
Xu
Ruiyan
R
Zhu
Yonghong
Y
Meng
D001412:Bacillus subtilis / Q000187:drug effects / Q000378:metabolism*; D002122:Calcium Chloride / Q000494:pharmacology*; D003470:Culture Media / Q000737:chemistry*; D004789:Enzyme Activation / Q000187:drug effects; D007656:Ketoglutaric Acids / Q000378:metabolism*; D010088:Oxidoreductases / Q000187:drug effects*; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D014783:Viscosity
D003470:Culture Media; D007656:Ketoglutaric Acids; C511775:poly(gamma-glutamic acid); D011099:Polyglutamic Acid; D010088:Oxidoreductases; D002122:Calcium Chloride