Improvement of poly(gamma-glutamic acid) biosynthesis and redistribution of metabolic flux with the presence of different additives in Bacillus subtilis CGMCC 0833.
Tween-80, dimethyl sulfoxide (DMSO), and glycerol could be used as novel materials to regulate the central carbon metabolic pathway and improve gamma-PGA biosynthesis by Bacillus subtilis CGMCC 0833. With glycerol in the medium, the activity of 2-oxoglutarate dehydrogenase complex at the key node of 2-oxoglutarate was depressed, more carbon flux distribution was directed to synthesize glutamate, the substrate of gamma-PGA, which led to overproducing of gamma-PGA, reached 31.7 g/l, compared to the original value of 26.7 g/l. When Tween-80 or DMSO was in the medium, the activity of isocitrate dehydrogenase was stimulated, the branch flux from 2-oxoglutarate to glutamate was also enhanced due to the increasing of total flux from iso-citrate to 2-oxoglutarate, then a large amount of glutamate was produced, and formation of gamma-PGA was also improved, which was a different process compared with that of glycerol. Moreover, with the addition of Tween-80 or DMSO, cell membrane permeability was increased, which facilitated the uptake of extracellular substrates and the secretion of gamma-PGA by this strain; therefore, gamma-PGA production was further stimulated, and 34.4 and 32.7 g/l gamma-PGA were obtained, respectively. This work firstly employed additives to improve the biosynthesis of gamma-PGA and would be helpful in understanding the biosynthesis mechanism of gamma-PGA by Bacillus species deeply.
Wu
Qun
Q
College of Life Science and Pharmacy, Nanjing University of Technology, Nanjing, China.
Xu
Hong
H
Shi
Ningning
N
Yao
Jun
J
Li
Sha
S
Ouyang
Pingkai
P
D001412:Bacillus subtilis / Q000201:enzymology / Q000302:isolation & purification / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D018533:Biomass; D053898:Biosynthetic Pathways; D002244:Carbon / Q000378:metabolism; D002463:Cell Membrane Permeability; D004121:Dimethyl Sulfoxide / Q000378:metabolism*; D004798:Enzymes / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism*; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000096:biosynthesis; D011136:Polysorbates / Q000378:metabolism*
D001426:Bacterial Proteins; D004798:Enzymes; D011136:Polysorbates; C511775:poly(gamma-glutamic acid); D011099:Polyglutamic Acid; D002244:Carbon; D005990:Glycerol; D004121:Dimethyl Sulfoxide