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Appl Microbiol Biotechnol. 2008 Jun;79(4):527-35. Epub 2008 Apr 29.
Improvement of poly(gamma-glutamic acid) biosynthesis and redistribution of metabolic flux with the presence of different additives in Bacillus subtilis CGMCC 0833.

Wu Q, Xu H, Shi N, Yao J, Li S, Ouyang P.

College of Life Science and Pharmacy, Nanjing University of Technology,
Nanjing, China.

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.

PMID: 18443783 [PubMed - indexed for MEDLINE]