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Here, focus is on Corynebacterium glutamicum mannose metabolic genes with the aim to improve this industrially important microorganism’s ability to ferment mannose present
in mixed sugar substrates. cgR_0857 encodes C. glutamicum’s protein with 36% amino acid sequence identity to mannose 6-phosphate isomerase encoded by manA of Escherichia coli. Its deletion mutant did not grow on mannose and exhibited noticeably reduced growth on glucose as sole carbon sources. In
effect, C. glutamicum manA is not only essential for growth on mannose but also important in glucose metabolism. A double deletion mutant of genes encoding
glucose and fructose permeases (ptsG and ptsF, respectively) of the phosphoenolpyruvate-dependent phosphotransferase system (PTS) was not able to grow on mannose unlike
the respective single deletion mutants with mannose utilization ability. A mutant deficient in ptsH, a general PTS gene, did not utilize mannose. These indicate that the glucose-PTS and fructose-PTS are responsible for mannose
uptake in C. glutamicum. When cultured with a glucose and mannose mixture, mannose utilization of manA-overexpressing strain CRM1 was significantly higher than that of its wild-type counterpart, but with a strong preference
for glucose. ptsF-overexpressing strain CRM2 co-utilized mannose and glucose, but at a total sugar consumption rate much lower than that of
the wild-type strain and CRM1. Strain CRM3 overexpressing both manA and ptsF efficiently co-utilized mannose and glucose. Under oxygen-deprived conditions, high volumetric productivity of organic acids
concomitant with the simultaneous consumption of the mixed sugars was achieved by the densely packed growth-arrested CRM3
cells. 相似文献
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Aims
To increase the l ‐isoleucine production in Corynebacterium glutamicum by overexpressing the global regulator Lrp and the two‐component export system BrnFE.Methods and Results
The brnFE operon and the lrp gene were cloned into the shuttle vector pDXW‐8 individually or in combination. The constructed plasmids were transformed into an l ‐isoleucine‐producing strain C. glutamicum JHI3‐156, and the l ‐isoleucine production in these different strains was analysed and compared. More l ‐isoleucine was produced when only Lrp was expressed than when only BrnFE was expressed. Significant increase in l ‐isoleucine production was observed when Lrp and BrnFE were expressed in combination. Compared to the control strain, l ‐isoleucine production in JHI3‐156/pDXW‐8‐lrp‐brnFE increased 63% in flask cultivation, and the specific yield of l ‐isoleucine increased 72% in fed‐batch fermentation.Conclusions
Both Lrp and BrnFE are important to enhance the l ‐isoleucine production in C. glutamicum.Significance and Impact of the Study
The results provide useful information to enhance l ‐isoleucine or other branched‐chain amino acid production in C. glutamicum. 相似文献6.
We analyzed 1,2-propanediol (1,2-PD) production in metabolically engineered Corynebacterium glutamicum. Wild-type C. glutamicum produced 93 μM 1,2-PD after 132 h incubation under aerobic conditions. No gene encoding the methylglyoxal synthase (MGS)
which catalyzes the first step of 1,2-PD synthesis from the glycolytic pathway was detected on the C. glutamicum genome, but several genes annotated as encoding putative aldo-keto reductases (AKRs) were present. AKR functions as a methylglyoxal
reductase in the 1,2-PD synthesis pathway. Expressing Escherichia coli mgs gene in C. glutamicum increased 1,2-PD yield 100-fold, suggesting that wild-type C. glutamicum carries the genes downstream of MGS in the 1,2-PD synthesis pathway. Furthermore, simultaneous overexpression of mgs and cgR_2242, one of the genes annotated as AKRs, enhanced 1,2-PD production to 24 mM. This work establishes that 1,2-PD synthesis by
C. glutamicum, previously unknown, is possible. 相似文献
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Hee-Sung Shin Yong-Jae Kim In-Hwa Yoo Heung-Shick Lee Shouguang Jin Un-Hwan Ha 《Biotechnology letters》2011,33(1):97-102
A genetic locus, encoding putative acyltransferase, was induced by autoinducers in Corynebacterium glutamicum. The autoinducers were maximally produced by the bacterium after 24 h culture. Those molecules are resistant to proteinase
K treatment (300 μg ml−1) for 30 min at 37°C or at 121°C for 15 min, and remained stable after extensive storage at 4°C. Autoinducers in the cell-free
culture fluids from Corynebacterium ammoniagenes and Pseudomonas aeruginosa also induced the expression of acyltransferase in C. glutamicum, suggesting possible cross-recognition of the autoinducers by C. glutamicum. C. glutamicum thus possesses an autoinduction system which secretes autoinducers during growth, triggering the expression of downstream
genes, exemplified by the putative acyltransferase gene. 相似文献
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Peng X Okai N Vertès AA Inatomi K Inui M Yukawa H 《Applied microbiology and biotechnology》2011,91(5):1375-1387
Corynebacterium glutamicum encodes a mannitol catabolic operon, which comprises three genes: the DeoR-type repressor coding gene mtlR (sucR), an MFS transporter gene (mtlT), and a mannitol 2-dehydrogenase gene (mtlD). The mtlR gene is located upstream of the mtlTD genes in the opposite orientation. In spite of this, wild-type C. glutamicum lacks the ability to utilize mannitol. This wild-type phenotype results from the genetic regulation of the genes coding for
mannitol transport and catalytic proteins mediated by the autoregulated MtlR protein since mtlR mutants grow on mannitol as the sole carbon source. MtlR binds to sites near the mtlR (two sites) and mtlTD promoters (one site downstream of the promoter), with the consensus sequence 5′-TCTAACA-3′ being required for its binding.
The newly discovered operon comprises the three basic functional elements required for mannitol utilization: regulation, transport,
and metabolism to fructose, further processed to the common intermediate of glycolysis fructose-6-phosphate. When relieved
from MtlR repression, C. glutamicum, which lacks a functional fructokinase, excretes the fructose derived from mannitol and imports it by the fructose-specific
PTS. In order to use mannitol from seaweed biomass hydrolysates as a carbon source for the production of useful commodity
chemicals and materials, an overexpression system using the tac promoter was developed. For congruence with the operon, we propose to rename sucR as the mtlR gene. 相似文献
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Osamu Kato Jung-Won Youn K Corinna Stansen Daisuke Matsui Tadao Oikawa Volker F Wendisch 《BMC microbiology》2010,10(1):321
Background
Corynebacterium glutamicum is able to grow with lactate as sole or combined carbon and energy source. Quinone-dependent L-lactate dehydrogenase LldD is known to be essential for utilization of L-lactate by C. glutamicum. D-lactate also serves as sole carbon source for C. glutamicum ATCC 13032. 相似文献18.
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Borbála Tihanyi Tibor Vellai Ágnes Regős Eszter Ari Fritz Müller Krisztina Takács-Vellai 《BMC developmental biology》2010,10(1):78