e-journal

The Auxiliary Substrate Concept: From simple considerations to heuristically valuable knowledge

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Microorganisms are used in biotechnology. They are either (i) aim and purpose of a
process, e.g. with the production of single cell proteins, or (ii) mean to an end insofar
as they serve as a catalyst or ‘‘factory’’ for syntheses (e.g. of products of primary and
secondary metabolism, of enzymes and antibiotics) or for the degradation and
detoxification of harmful organics and inorganics. In all cases, the efficiency and
velocity, finally the productivity, are parameters which essentially determine the
economy of the processes. Therefore, search for approaches to optimize these
processes is a permanent task and challenge for scientists and engineers. It is shown
that the auxiliary substrate concept is suitable to increase the yield coefficients. It is
based on the energetic evaluation of organics, on the knowledge that organics as
sources of carbon and energy for growth are deficient in ATP and/or reducing
equivalents, and says that it is possible to improve the carbon conversion efficiency up
to the carbon metabolism determined upper limit. The latter is determined by
inevitable losses of carbon along the way of assimilation and anabolism and amounts
to about 85% for so-called glycolytic substrates, e.g. glucose, methanol, and to about
75% for gluconeogenetic substrates, e.g. C2-substrates (acetic acid, hexadecane). The
approach is explained and some experimental examples are presented. By simultaneous
utilization of an extra energy source (auxiliary substrate) the yield coefficient
can be increased (i) in glucose from about 0.5 to 0.7 g/g (by means of formate), (ii) in
acetate from 0.34–0.4 to 0.5–0.65 g/g (by means of formate and thiosulfate, respectively),
and (iii) in hexadecane from about 0.94 to 1.26 g/g (by means of formate).
The precalculated yield coefficients and mixing ratios agree well with the experimentally
attained ones. The approach is easily feasible and economically valuable.

Keywords: Auxiliary substrate / Energetic evaluation / Upper limit / Yield coefficient

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Informasi Detail

Judul Seri

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No. Panggil

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Penerbit

New York : WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim., 2009

Deskripsi Fisik

Eng. Life Sci. 2009, 9, No. 4, 285–290

Bahasa

English

ISBN/ISSN

DOI: 10.1002/elsc.20

Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

2009, 9, No. 4, 285–290

Subjek

TEKNIK LINGKUNGAN

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

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