Enhanced glutamic acid production by a H+-ATPase-defective mutant of Corynebacterium glutamicum.
Previously we reported that a mutant of Corynebacterium glutamicum ATCC14067 with reduced H+-ATPase activity, F172-8, showed an approximately two times higher specific rate of glucose consumption than the parent, but no glutamic acid productivity under the standard biotin-limited culture conditions, where biotin concentration was set at 5.5 microg/l in the production medium (Sekine et al., Appl. Microbiol. Biotechnol., 57, 534-540 (2001)). In this study, various culture conditions were tested to check the glutamic acid productivity of strain F172-8. The mutant was found to produce glutamic acid under exhaustive biotin limitation, where the biotin concentration of the medium was set at 2.5 microg/l with much smaller inoculum size. When strain F172-8 was cultured under the same biotin-limited conditions using a jar fermentor, 53.7 g/l of glutamic acid was produced from 100 g/l glucose, while the parent produced 34.9 g/l of glutamic acid in a medium with 5.5 microg/l biotin. The glutamic acid yield of strain F172-8 also increased under Tween 40-triggered production conditions (1.2-fold higher than the parent strain). The amounts of biotin-binding enzymes were investigated by Western blot analysis. As compared to the parent, the amount of pyruvate carboxylase was lower in the mutant; however, the amount of acetyl-CoA carboxylase did not significantly change under the glutamic acid production conditions. To the best of our knowledge, this is the first report showing that the H+-ATPase-defective mutant of C. glutamicum is useful in glutamic acid production.
Aoki
Ryo
R
Laboratory of Microbial Resources and Ecology, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan.
Wada
Masaru
M
Takesue
Nobuchika
N
Tanaka
Kenji
K
Yokota
Atsushi
A
D001710:Biotin / Q000378:metabolism; D048230:Corynebacterium glutamicum / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D005285:Fermentation; D018698:Glutamic Acid / Q000096:biosynthesis*; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*
D018698:Glutamic Acid; D001710:Biotin; D006180:Proton-Translocating ATPases