Modeling of Growth, Lactate Consumption, and Volatile Fatty Acid Production by Megasphaera elsdenii Cultivated in Minimal and Complex Media

Abstract

Use of the Pirt and Luedeking-Piret equations permits the determination of the effect of medium composition on the metabolic patterns of Megasphaera elsdenii grown in minimal and complex media with lactate as the major carbon source. To establish the significance of the parameters involved in the Pirt and Luedeking-Piret equations, a quantitative statistical criterion was proposed. In the complex medium, lactate was completely used for growth and product formation, whereas in the minimal medium a fraction of the energy obtained from lactate was used for maintenance purposes. Modeling of VFA production by the Luedeking-Piret equation showed that, independent of the type of medium, acetate and propionate are growth-associated products, while butyrate and valerate are only partially growth-associated. The growth-associated products are related to energy-yielding metabolism and the non-growth-associated products are related to the consumption of reducing equivalents.

Improvement of growth, fermentative efficiency and ethanol tolerance of Kloeckera africana during the fermentation of Agave tequilana juice by addition of yeast extract

“…Response variables were final biomass, reducing sugar and ethanol concentrations, biomass and ethanol yields and specific growth rate. Kinetic parameters were calculated from the experimental data using the Marquardt ‘Solver’ (Excel, Microsoft) and fitted by the logistic, Pirt and Luedeking‐Piret equations 24…”

Differences in growth physiology and aggregation of Pichia pastoris cells between solid‐state and submerged fermentations under aerobic conditions

“…The integrated form of Equation is shown in Equation as follows: where S is the substrate concentration (g L −1 ); Y x / s is the biomass/substrate yield (g biomass g −1 glycerol), S 0 is the initial concentration of substrate, S ( x ) is the substrate concentration corresponding to each X ( t ) value, and m is the maintenance coefficient (g glycerol g −1 biomass h −1 ), the parameters S 0 , Y x / s , and m were estimated by minimizing the sum of least squares of residual errors between the integrated data using Equation and the observed values of S ( x ) for each fermentation run, yielding R 2 > 0.91; the data analysis‐linear regression of Excel Microsoft ® tool was used.…”

A comparative study of Taxol production in liquid and solid-state fermentation with Nigrospora sp. a fungus isolated from Taxus globosa

“…2006). Soto‐Cruz et al. (2002) used a singular mathematical procedure followed by integration to obtain a set of equations to describe growth, substrate and fatty acid production by Megasphaera elsdenii.…”

“…1993). Subsequently, the logistic, Pirt and Luedeking–Piret models were used to model biomass, sugar consumption and Taxol production, respectively (Soto‐Cruz et al. 2002).…”

“…In each case, the fungus was grown in media at two (2·), four (4·), six (6·) and eight times (8·) the original M1D-medium concentration (Stierle et al 1993). Subsequently, the logistic, Pirt and Luedeking-Piret models were used to model biomass, sugar consumption and Taxol production, respectively (Soto-Cruz et al 2002).…”