Production of L-lysine and L-lysine-containing feed additives

Wendisch VF, Bathe B. Production of L-lysine and L-lysine-containing feed additives. 07.08.2008

Method for fermentatively preparing L-amino acids

Wendisch VF, Lindner S, Bathe B, Claes W. Method for fermentatively preparing L-amino acids. 29.10.2010

Characterization of Methionine Export in Corynebacterium glutamicum

Corynebacterium glutamicum is known for its effective excretion of amino acids under particular metabolic conditions. Concomitant activities of uptake and excretion systems would create an energy-wasting futile cycle; amino acid export systems are therefore tightly regulated. We have used a DNA microarray approach to identify genes for membrane proteins which are overexpressed under conditions of elevated cytoplasmic concentrations of methionine. One of these genes was brnF, coding for the larger subunit of BrnFE, a previously identified two-component isoleucine export system. By deletion, complementation, and overexpression of the brnFE genes in a C. glutamicum strain, in which the two uptake systems for methionine were inactivated, we identified BrnFE as being responsible for methionine export. In the presence of both substrates in the cytoplasm, BrnFE was found to transport isoleucine and methionine at similar rates. The expression of the brnFE gene cluster depends on an Lrp-type transcription factor and was shown to be strongly induced by increasing cytoplasmic methionine concentration. Methionine was a better inducer than isoleucine, indicating that methionine rather than isoleucine might be the native substrate of BrnFE. When the synthesis of BrnFE was blocked by chloramphenicol, fast methionine export was still observed, but only at greatly increased cytoplasmic levels of this amino acid. This indicates the presence of at least one other methionine export system, presumably with low affinity but high capacity. Under conditions where cytoplasmic methionine does not exceed a concentration of 50 mM, BrnFE is the dominant export system for this amino acid

Characterization of myo-Inositol Utilization by Corynebacterium glutamicum: the Stimulon, Identification of Transporters, and Influence on l-Lysine Formation

Although numerous bacteria possess genes annotated iol in their genomes, there have been very few studies on the possibly associated myo-inositol metabolism and its significance for the cell. We found that Corynebacterium glutamicum utilizes myo-inositol as a carbon and energy source, enabling proliferation with a high maximum rate of 0.35 h(−1). Whole-genome DNA microarray analysis revealed that 31 genes respond to myo-inositol utilization, with 21 of them being localized in two clusters of >14 kb. A set of genomic mutations and functional studies yielded the result that some genes in the two clusters are redundant, and only cluster I is necessary for catabolizing the polyol. There are three genes which encode carriers belonging to the major facilitator superfamily and which exhibit a >12-fold increased mRNA level on myo-inositol. As revealed by mutant characterizations, one carrier is not involved in myo-inositol uptake whereas the other two are active and can completely replace each other with apparent K(m)s for myo-inositol as a substrate of 0.20 mM and 0.45 mM, respectively. Interestingly, upon utilization of myo-inositol, the l-lysine yield is 0.10 mol/mol, as opposed to 0.30 mol/mol, with glucose as the substrate. This is probably not only due to myo-inositol metabolism alone since a mixture of 187 mM glucose and 17 mM myo-inositol, where the polyol only contributes 8% of the total carbon, reduced the l-lysine yield by 29%. Moreover, genome comparisons with other bacteria highlight the core genes required for growth on myo-inositol, whose metabolism is still weakly defined

Process for the fermentative preparation of organic chemical compounds using coryneform bacteria in which the SugR gene is present in attenuated form

Bathe B, Blombach B, Eikmanns B, Engels V, Thierbach G, Wendisch VF. Process for the fermentative preparation of organic chemical compounds using coryneform bacteria in which the SugR gene is present in attenuated form. 13.03.2012