Population heterogeneity and signal transduction Group


Dr. Julia Frunzke
Institute of Biotechnology 1
Forschungszentrum Jülich GmbH
52425 Jülich
Germany
Phone: +49 (2461) 61-5430
Fax: +49 (2461) 61-2710
E-Mail:  j.frunzke@fz-juelich.de
 group photo
Our group in November 2009

 Group Members
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Population heterogeneity in industrial microorganisms



Fig. 1 Genome heterogeneity caused by the induction of the CGP3 prophage (Frunzke et al. 2008b). 		In recent literature numerous studies have been described which reveal that clonal populations of microorganisms living in the same environment often show surprisingly high variation in phenotypic traits. Thus, even though a typical culture of bacteria looks quite homogenous to the human eye, a closer look on the level of gene expression, enzyme activity, or metabolism often reveals drastic cell-to-cell variation. The variability of these traits can of course be the result of mutations or genetic rearrangements but as well arise due to variation in cell-specific factors such as the metabolic state, cell age or so-called intrinsic noise which arises from the stochastic nature of gene expression.

Accordingly, biologists have realized that averaging data retrieved by analyzing bulks of cells can obscure critical information about cell-to-cell variation. We plan to use novel tools to monitor and, more importantly, to understand cell-to-cell variations of industrial production strains with regard to gene expression and product formation. As main model organism we use the Gram-positive soil bacterium Corynebacterium glutamicum which is used today for the industrial production of more than two million tons of amino acids per year, mainly L-glutamate and L-lysine.



Metal ion homeostasis

Microorganisms living in a complex and varying environment as the soil must be able to take up all essential metal ions but at the same time must limit free intracellular levels to prevent toxicity. We have described transcriptional regulators which constitute a complex hierarchical regulatory network controlling iron homeostasis in the Gram-positive soil bacterium Corynebacterium glutamicum. Iron is an essential trace element for almost all organisms as it participates in major biological processes, such as the TCA cycle and the respiratory chain. As a consequence, the iron availability in the growth medium has a strong impact on cellular metabolism and thus productivity of C. glutamicum. Current projects in our group focus on the identification of additional players in this complex regulatory network as well as the investigation of further metalloregulatory proteins.

Fig.: 2: Control of iron homeostasis in
C. glutamicum.

Cooperations

  1. Marc Bramkamp,  Universität Köln.
  2. Julia Vorholt,  ETH Zürich.

last change 18.03.2010 | | Print