On-line estimation of biomass through pH control analysis in aerobic yeast fermentation systems

Vicente, António A.; Castrillo, Juan I.; Teixeira, J. A.; Ugalde, Unai

doi:10.1002/(sici)1097-0290(19980520)58:4<445::aid-bit12>3.0.co;2-a

Cited by 30 publications

(4 citation statements)

References 33 publications

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“…Along with this reaction the extracellular medium is acidified and has to be neutralized by the addition of base. The amount of base required for neutralization could be correlated to the uptake of NH 3 , which is present as NH 4 + in the extracellular medium and therefore liberating protons (Vicente et al, 1998). Ammonia is incorporated in the cell with a molar fraction x N (mol N (C-mol biomass) −1 ), which can be measured by elemental analysis.…”

Section: Stoichiometry For Oxidative and Oxidoreductive Growthmentioning

confidence: 99%

Generally applicable fed‐batch culture concept based on the detection of metabolic state by on‐line balancing

Jobé

Herwig

Surzyn

et al. 2003

Biotech & Bioengineering

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In many microorganisms, flux limitations in oxidative metabolism lead to the formation of overflow metabolites even under fully aerobic conditions. This can be avoided if the specific growth rate is controlled at a low enough value. This is usually accomplished by controlling the substrate feeding profile in a fed-batch process. The present work proposes a control concept which is based on the on-line detection of metabolic state by on-line calculation of mass and elemental balances. The advantages of this method are: 1) the check of measurement consistency based on all of the available measurements, 2) the minimum requirement of a priori knowledge of metabolism, and 3) the exclusive use of simple and established on-line techniques which do not require direct measurement of the metabolite in question. The control concept has been linked to a simple adaptive controller and applied to fed-batch cultures of S. cerevisiae and E. coli, organisms which express different overflow metabolites, ethanol and acetic acid, respectively. Oxidative and oxidoreductive states of S. cerevisiae and E. coli cultures were detected with high precision. As demonstrated by the formation of acetic acid in E. coli cultures, metabolic states could be correctly distinguished for systems for which traditional methods, such as respiratory quotient (RQ), are insensitive. Hence, it could be shown that the control concept allowed avoidance of overflow metabolite formation and operation at maximum oxidative biomass productivity and oxidative conversion of substrate into biomass. Based on mass and elemental balances, the proposed method additionally provides a richness of additional information, such as yield coefficients and estimation of concentrations and specific conversion rates. These data certainly help the operator to additionally evaluate the state of the process on-line.

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Section: Stoichiometry For Oxidative and Oxidoreductive Growthmentioning

confidence: 99%

Generally applicable fed‐batch culture concept based on the detection of metabolic state by on‐line balancing

Jobé

Herwig

Surzyn

et al. 2003

Biotech & Bioengineering

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“…(1) because it is negligible (see Bicarbonate Buffer System of Siano, 1995). Castrillo et al (1995) and Vicente et al (1998) showed that the pH control reagent addition rate (r reag ) is only affected by the primary pH-affecting metabolites, as indicated in Eq. (1a), i.e., all other biological and solution chemistry effects are negligible (Siano, 1995).…”

Section: Abiotic Proton Balancementioning

confidence: 99%

“…Castrillo et al (1995) cultivated yeast in a chemostat under respiratory metabolism of glucose or glycerol with ammonia, urea, or nitrate as the nitrogen source. Vicente et al (1998) cultivated yeast in a chemostat under respiro-fermentative metabolism of glucose or ethanol with urea as the nitrogen source. In all cases, r reag (or q H + in their work) was primarily due to the pHaffecting metabolite (ammonia or nitrate) and was negligible when the nitrogen source was urea, which is not a pH-affecting metabolite.…”

Section: Abiotic Proton Balancementioning

confidence: 99%

Use of the abiotic proton balance for describing the pH-auxostat

Siano¹

1999

Biotechnol. Bioeng.

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A new description of the pH‐auxostat is obtained by using the abiotic proton balance in the mathematical model. The new model shows how the stoichiometry of metabolism affects the steady‐state and stability characteristics of the pH‐auxostat. The model can also be used to determine the amount of ammonium salts to include in the medium, and can be applied to the pH‐stat modal fed‐batch reactor and the bistat. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 64: 755–758, 1999.

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“…Methods that measure physical variables are generally better adapted for on-line, in-situ biomass mea-surements (Harris and Kell, 1985;Vicente et al, 1998;Hoffmann et al, 2000;Neves et al, 2000;Arnold et al, 2002). One of these is dielectric spectroscopy, which 75 is a direct technique useful only with high cell concentrations, i.e., higher than 2-5 • 10 5 cell/ml for yeast or animal cells (Ducommun et al, 2002;.…”

Section: Introduction a General Conceptsmentioning

confidence: 99%

Microbial Biomass Estimation

Madrid

Felice

2005

Critical Reviews in Biotechnology

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The development of a fully automated on-line monitoring and control system is very important in bioprocesses. One of the most important parameters in these processes is biomass. This review discusses different methods for biomass quantification. A general definition of biomass and biovolume are presented. Interesting concepts about active but not culturable cells considerations are included as well as concepts that must be taken into account when selecting biomass quantification technology. Chemical methods have had few applications in biomass measurement to date; however, bioluminescence can selectively enumerate viable cells. Photometric methods including fluorescence and scattered light measurements are presented. Reference methods including dry and wet weight, viable counts and direct counts are discussed, as well as the physical methods of flow cytometry, impedancimetric and dielectric techniques.

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On-line estimation of biomass through pH control analysis in aerobic yeast fermentation systems

Cited by 30 publications

References 33 publications

Generally applicable fed‐batch culture concept based on the detection of metabolic state by on‐line balancing

Generally applicable fed‐batch culture concept based on the detection of metabolic state by on‐line balancing

Use of the abiotic proton balance for describing the pH-auxostat

Microbial Biomass Estimation

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