C[O.sub.2]/HC[O.sub.3.sup.-] perturbations of simulated large scale gradients in a scale-down device cause fast transcriptional responses in Corynebacterium glutamicum

• Published in: Applied microbiology and biotechnology Vol. 98; no. 20; pp. 8563 - 8572
• Main Authors: Buchholz, Jens, Graf, Michaela, Freund, Andreas, Busche, Tobias, Kalinowski, Jorn, Blombach, Bastian, Takors, Ralf
• Format: Journal Article
• Language: English
• Published: Springer 15.10.2014
• Subjects: Analysis; Corynebacteria; Genetic aspects; Genetic transcription
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-014-6014-y

The exploration of scale-down models to imitate the influence of large scale bioreactor inhomogeneities on cellular metabolism is a topic with increasing relevance. While gradients of substrates, pH, or dissolved oxygen are often investigated, oscillating C[O.sub.2]/HC[O.sub.3.sup.-] levels, a typical scenario in large industrial bioreactors, is rarely addressed. Hereby, we investigate the metabolic and transcriptional response in Corynebacterium glutamicum wild type as well as the impact on L-lysine production in a model strain exposed to pC[O.sub.2] gradients of (75-315)mbar. A three-compartment cascade bioreactor system was developed and characterized that offers high flexibility for installing gradients and residence times to mimic industrial-relevant conditions and provides the potential of accurate carbon balancing. The phenomenological analysis of cascade fermentations imposed to the pC[O.sub.2] gradients at industry-relevant residence times of about 3.6 min did not significantly impair the process performance, with growth and product formation being similar to control conditions. However, transcriptional analysis disclosed up to 66 differentially expressed genes already after 3.6 min under stimulus exposure, with the overall change in gene expression directly correlateable to the pC[O.sub.2] gradient intensity and the residence time of the cells.