Metabolite overproduction

In order to develop a rational approach to improving rates of metabolite production, it is necessary to consider the fate of the nutrients that are required for its synthesis. However, overcoming the major flux control points within a metabolic pathway may not lead to metabolite overproduction if the energetic consequences of the alteration are unfavourable to the organism. 

Goodacre, R. Trew, S. Wrigley-Jones, C. Neal, M. J. Maddock, J. Ottley, T. W. Porter, N. Kell, D. B. Rapid screening for metabolite overproduction in fermentor broths using pyrolysis mass spectrometry with multivariate calibration and artificial neural networks. Biotechnol. Bioengin. 1994, 44,1205-1216. 

DRASTIC) A hyperspectral FT-IR-based approach to rapid screening for metabolite overproduction. Hna/yhca Chimica Acta, 348, 273-282. 

Kell DB, Winson MK, Goodacre R, Woodward AM, Alsberg BK, Jones A, Timmins EM, Rowland JJ (1998) DRASTIC (Diffuse Reflectance Absorbance Spectroscopy Taking In Chemometrics). A novel, rapid, hyperspectral, FT-IR-based approach to screening for biocatalytic activity and metabolite overproduction. In Kieslich K (ed) New Frontiers in Screening for Microbial Biocatalysts. Elsevier Science B. V., The Netherlands, p 61... 

Metabolite overproduction and growth efficiency Summary and objectives... 

DRASTIC (Diffuse Reflectance Absorbance Spectroscopy Taking In Chemometrics). a novel, rapid, hyperspectral, FT-IR-based approach to screening for biocatalytic activity and metabolite overproduction... 

In analysing complex fermentor broths and supernatants, in contrast to the case for simple mixtures, the multivariate analysis approach not only monitors the infra-red spectral contribution of the target molecules per se but may also take into account other features associated with the metabolite concentration. In this way the use of unsupervised methods such as PCA and supervised methods such as PLS, and DFA can exploit differences in the organism (for example the mutant type) or the medium which correlate with metabolite overproduction. This can provide a useful amplification to the method when the target molecule concentrations are particularly low. 

Chemical mutagenesis of microbial strains typically produces mutants with a range of metabolite overproduction capabilities. In the case of S. citricolor, mutants have been isolated which produce either aristeromycin, or neplanocin A, or both molecules, at higher levels. In strain development programmes efficient identification of those mutants overproducing target molecules is of key importance. 

The results of this study, using quantification of aristeromycin and neplanocin A in a model S. citricolor fermentation system, illustrate for the first time that the DRASTIC approach provides a novel, rapid and successful method for screening microbial strains for metabolite overproduction in titre improvement programmes. 

Winson, M. K., Goodacre, R., Timmins, E. et al (1997a) Diffuse reflectance absorbance spectroscopy taking in chemometrics (DRASTIC). A hyperspectral FT-IR-based approach to rapid screening for metabolite overproduction. Analytica Chimica Acta, in press. 

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