Analysis of carbon metabolism and improvement of gamma-polyglutamic acid production from Bacillus subtilis NX-2.
Bacillus subtilis NX-2 produces gamma-polyglutamic acid (gamma-PGA) when using glucose and L-glutamate as carbon sources. The conversion of carbon sources into gamma-PGA was analyzed with the (13)C-NMR method after enriching the media with (13)C-labeled glucose. The results showed that the percentage of gamma-PGA monomers derived from glucose was relatively low, approximately 6% and 9%, respectively, with an initial glucose concentration of 30 and 40 g L(-1). It was concluded that glucose was utilized mainly as the growth-limiting substrate for cell growth and supplied the required energy during gamma-PGA biosynthesis, while L-glutamate was preferred as the main substrate for gamma-PGA formation. To achieve an efficient conversion of L-glutamate and enhance the gamma-PGA production, a fed-batch culture was proposed by feeding of glucose. By this method, supplied L-glutamate (40 g L(-1)) was completely depleted, and gamma-PGA yield was attained 42 g L(-1).
Yao
Jun
J
Department of Biotechnology, School of Basic Medical Science, Nanjing Medical University, Nanjing, 210029, People's Republic of China.
Xu
Hong
H
Shi
Ningning
N
Cao
Xin
X
Feng
Xiaohai
X
Li
Sha
S
Ouyang
Pingkai
P
D001412:Bacillus subtilis / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D007553:Isotope Labeling; D019906:Nuclear Magnetic Resonance, Biomolecular; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000378:metabolism
C511775:poly(gamma-glutamic acid); D011099:Polyglutamic Acid; D018698:Glutamic Acid; D002244:Carbon; D005947:Glucose