Transcriptomics and quantitative physiology of ß-lactam producing Penicillium chrysogenum

Transcriptomics and quantitative physiology of ß-lactam producing Penicillium chrysogenum

Harris, D.M.

Pronk, J.T. (promotor)

Applied Sciences

Biotechnology

2008-03-11

With an over 1000-fold improvement in specific productivity since its discovery, penicillin is one of the very successful examples of industrial biotechnology. Although classical strain improvement programmes have been a major contributor to this success, the wish for a more rational approach towards improvements has driven the work described in this thesis. As most ß-lactam biosynthesis routes share the first steps in their pathway, the production of penicillin-G in chemostat cultivations of P. chrysogenum has been chosen as a model system. Compared to common laboratory organisms such as bakers' yeast, the information on P. chrysogenum is relatively limited, which also reduces the range of possibilities for a rational approach. The majority of the work described in this thesis can therefore be assigned to the analysis phase of the metabolic engineering cycle. In the first half of the thesis more classical techniques are employed to investigate two important aspects of ß-lactam production: NADPH metabolism and the unexpectedly high energy demand of penicillin production. The work presented in the second half of this thesis was made possible by the availability of the genome sequence of P. chrysogenum. A whole series of transcriptome studies of chemostat based cultivations of P. chrysogenum was set up with the aim to identify key factors involved in penicillin production. Using this experimental design it was possible to explore transcriptional responses towards ß-lactam production and side chain catabolism at a genome-wide scale. Each of these studies has provided putative targets for metabolic engineering of ß-lactam production by Penicillium chrysogenum.

penicillium chrysogenum
penicillin transcriptomics
metabolic engineering
micro-array
ß-lactam
chemostat
phenylacetic acid

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Institutional Repository

doctoral thesis

(c) 2008 Harris, D.M.