Use of Various Measurements for Biomass Estimation

Abstract

Electron, carbon, and nitrogen balances can be thought of as relationships among the time rates of change of the various compounds participating in a fermentation process. As such, they define the minimum number of necessary measurements from which the remaining rates can be determined through the use of the balances. All possibilities, however, are not equivalent, and some of them lead to singularities and solutions of high sensitivity. These possibilities are reviewed in this paper, and suggestions are offered in regard t o the combination of rate measurements from which robust biomass estimates can be produced.

Microbial Cellulose Utilization: Fundamentals and Biotechnology

“…Compounds other than protein and nitrogen have been used in studies involving solid substrates as indicators of cell concentration, including phospholipids (190), DNA (244,631), ATP (677), glucosamine (154), dehydrogenase activity (209), chitin (307), gene probes (640), and cell-specific antibodies (364). Metabolic measurements (e.g., of nutrient consumption, CO 2 or heat evolution, and product formation) provide an additional class of methods that have been applied to the determination of cell concentration in the presence of solid substrates (98,324). Such measurements are useful if the cell yield relative to the measured quantity is known with certainty from prior work, which is seldom the case for cellulolytic microorganisms.…”

Quantitative determination of cellulase concentration as distinct from cell concentration in studies of microbial cellulose utilization: Analytical framework and methodological approach

“…Determination of cell mass in the presence of solid substrates has been reported based on measurement of a component common to cells and cellulase such as protein (CordovaLopez et al, 1996;Kennedy et al, 1992a;Mitchell et al, 1991) or nitrogen (Lynd et al, 1989;Weimer et al, 1991); a cell-speci®c component such as phospholipids (Findlay et al, 1989), ATP (Thierry and Chicheportiche, 1988), DNA (Hashimoto et al, 1982;Solomon et al, 1983), glucosamine (Desgranges et al, 1991), dehydrogenase activity (Ghaly et al, 1989), chitin (Ito et al, 1989), species-speci®c RNA (Stean et al, 1989), or species-speci®c antibodies (Kurane et al, 1979); nutrient consumption, evolution of CO 2 , calorimetric measurements, or product formation (see Chattaway et al, 1992; Kennedy et al, 1992a for reviews); or a physical property such as dielectric permittivity (Harris et al, 1987), osmotic pressure (Aoyagi et al, 1995), or light scattering (with deconvolution) (Kennedy et al, 1992b).…”

Use of the abiotic proton balance for determining linear relations among net conversion rates of primary metabolites in fermentation processes

“…For the Gibbs free energy balance, the additional unknown is the Gibbs free energy dissipation rate, which cannot be measured. Furthermore, the molar enthalpy is typically proportional to the degree of reduction for biological compounds, and hence may not introduce additional information (Chattaway et al, 1992); the molar Gibbs free energies are concentration dependent and cannot in practice be obtained accurately (Noorman et al, 1991).…”

“…In this manner, measurement of a subset of the net conversion rate vector allows the calculation of some (partially observable process) or all (fully observable process) of the remaining (unmeasured) net conversion rates. However, the utility of these methods is limited by the lack of available measurements and the need for additional independent balances (Chattaway et al, 1992).…”