The impact of PHB accumulation on l-glutamate production by recombinant Corynebacterium glutamicum

ABSTRACT Gene expression changes of glutamate-producing Corynebacterium glutamicum were identified in transcriptome comparisons by DNA microarray analysis. During glutamate production induced by a temperature shift, C. glutamicum strain 2262 showed significantly higher mRNA levels of the NCgl2816 and NCgl2817 genes than its non-glutamate-producing derivative 2262NP. Reverse transcription-PCR analysis showed that the two genes together constitute an operon. NCgl2816 putatively codes for a lactate permease, while NCgl2817 was demonstrated to encode quinone-dependent l-lactate dehydrogenase, which was named LldD. C. glutamicum LldD displayed Michaelis-Menten kinetics for the substrate l-lactate with a Km of about 0.51 mM. The specific activity of LldD was about 10-fold higher during growth on l-lactate or on an l-lactate-glucose mixture than during growth on glucose, d-lactate, or pyruvate, while the specific activity of quinone-dependent d-lactate dehydrogenase differed little with the carbon source. RNA levels of NCgl2816 and lldD were about 18-fold higher during growth on l-lactate than on pyruvate. Disruption of the NCgl2816-lldD operon resulted in loss of the ability to utilize l-lactate as the sole carbon source. Expression of lldD restored l-lactate utilization, indicating that the function of the permease gene NCgl2816 is dispensable, while LldD is essential, for growth of C. glutamicum on l-lactate.

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An improved temperature-triggered process for glutamate production with Corynebacterium glutamicum

Enzyme and Microbial Technology ◽

10.1016/s0141-0229(99)00120-9 ◽

1999 ◽

Vol 25 (8-9) ◽

pp. 762-768 ◽

Cited By ~ 36

Author(s):

S. Delaunay ◽

P. Gourdon ◽

P. Lapujade ◽

E. Mailly ◽

E. Oriol ◽

...

Keyword(s):

Corynebacterium Glutamicum ◽

Glutamate Production

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Glutamate production by Corynebacterium glutamicum: dependence on the oxoglutarate dehydrogenase inhibitor protein OdhI and protein kinase PknG

Applied Microbiology and Biotechnology ◽

10.1007/s00253-007-0933-9 ◽

2007 ◽

Vol 76 (3) ◽

pp. 691-700 ◽

Cited By ~ 75

Author(s):

Christian Schultz ◽

Axel Niebisch ◽

Lena Gebel ◽

Michael Bott

Keyword(s):

Protein Kinase ◽

Corynebacterium Glutamicum ◽

Inhibitor Protein ◽

Glutamate Production ◽

Oxoglutarate Dehydrogenase

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Impact of Heterologous Expression of Escherichia coli UDP-Glucose Pyrophosphorylase on Trehalose and Glycogen Synthesis in Corynebacterium glutamicum

Applied and Environmental Microbiology ◽

10.1128/aem.70.7.3845-3854.2004 ◽

2004 ◽

Vol 70 (7) ◽

pp. 3845-3854 ◽

Cited By ~ 20

Author(s):

Leandro Padilla ◽

Susanne Morbach ◽

Reinhard Krämer ◽

Eduardo Agosin

Keyword(s):

Escherichia Coli ◽

Heterologous Expression ◽

Corynebacterium Glutamicum ◽

Glycogen Synthesis ◽

Glycogen Accumulation ◽

E Coli ◽

Wide Range ◽

The Impact ◽

Synthetic Operon ◽

Trehalose Synthesis

ABSTRACT Trehalose is a disaccharide with a wide range of applications in the food industry. We recently proposed a strategy for trehalose production based on improved strains of the gram-positive bacterium Corynebacterium glutamicum. This microorganism synthesizes trehalose through two major pathways, OtsBA and TreYZ, by using UDP-glucose and ADP-glucose, respectively, as the glucosyl donors. In this paper we describe improvement of the UDP-glucose supply through heterologous expression in C. glutamicum of the UDP-glucose pyrophosphorylase gene from Escherichia coli, either expressed alone or coexpressed with the E. coli ots genes (galU otsBA synthetic operon). The impact of such expression on trehalose accumulation and excretion, glycogen accumulation, and the growth pattern of new recombinant strains is described. Expression of the galU otsBA synthetic operon resulted in a sixfold increase in the accumulated and excreted trehalose relative to that in a wild-type strain. Surprisingly, single expression of galU also resulted in an increase in the accumulated trehalose. This increase in trehalose synthesis was abolished upon deletion of the TreYZ pathway. These results proved that UDP-glucose has an important role not only in the OtsBA pathway but also in the TreYZ pathway.

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