# Empirical elemental formula for biomass

Range | C:H(1.613):O(0.557):N(0.158) |
---|---|

Organism | Budding yeast Saccharomyces cerevisiae |

Reference | von Stockar, U. Liu, J. Does microbial life always feed on negative entropy? Thermodynamic analysis of microbial growth. 1999. Biochim Biophys Acta. 1412(3) p.198 table 4PubMed ID10482783 |

Primary Source | [33] J.A. Roels, Energetics and Kinetics in Biotechnology, Elsevier, Amsterdam, 1983. [38] Edwin H. Battley, Robert L. Putnam, Juliana Boerio-Goates, Heat capacity measurements from 10 to 300 K and derived thermodynamic functions of lyophilized cells of Saccharomyces cerevisiae including the absolute entropy and the entropy of formation at 298.15 K, Thermochim. Acta 298 (1997) 37-46. doi:10.1016/S0040-6031(97)00108-1 [39] Edwin H. Battley, An empirical method for estimating the entropy of formation and the absolute entropy of dried microbial biomass for use in studies on the thermodynamics of microbial growth, Thermochim. Acta 326 (1999) 7-15. doi:10.1016/S0040-6031(98)00584-X |

Method | P.198 left column bottom paragraph: "The entropy can be directly determined using low-temperature calorimetry. The first to apply this technique to microbial biomass were Battley et al. [primary source 38]. They measured the heat capacity of lyophilized Saccharomyces cerevisiae cells over a temperature range of 10–300 K, and consequently determined the entropy of the dried biomass. Assuming that the entropy of hydration and the residual entropy of biomass are small enough to be neglected, the Gibbs energy of combustion is calculated to be −515.0 kJ/C-mol. More recently, Battley [primary source 39] proposed an empirical method to estimate the entropy of the biomass based on the atomic entropies of the atoms comprising the biomass. As he showed, this method gives very good accuracy as compared to the values calculated based on the experimentally determined entropies. The results of the reported work on the entropies and Gibbs energies of combustion of biomass are summarized in Table 4." |

Comments | P.198 right column 2nd paragraph: "As seen in Table 4, the Gibbs energy of combustion for S. cerevisiae that was determined using the experimental value of entropy is within 1% of the value estimated with Roels’ correlation, or Battley’s empirical method. Therefore, it is hypothesized that the Gibbs energy of combustion for other microorganisms may also be estimated by using Roels’ correlation or Battley’s method without introducing large error in the calculation of Gibbs energy changes. In most cases, the value for average biomass (−541.2 kJ/C-mol) may be used, though some further error might be introduced." This means that for every mole of carbon, there are 1.613 moles of hydrogen, 0.557 moles of oxygen and 0.158 moles of nitrogen. There are also 0.012 moles of phosphorus, 0.003 of sulfur, 0.003 of magnesium, 0.022 of potassium and 0.001 of calcium. |

Entered by | Phil Mongiovi |

ID | 101801 |