Affiliation:
1. Institute of Biotechnology, Research Centre Juelich, D-52425 Juelich, Germany
2. Degussa R&D Feed Additives/Biotechnology, P.O. Box 1112, D-33788 Halle, Germany
3. Institute of Molecular Microbiology and Biotechnology, University of Münster, Corrensstrasse 3, D-48149 Münster, Germany
Abstract
ABSTRACT
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.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology