Elemental composition, heat capacity from 2 to 300 K and derived thermodynamic functions of 5 microorganism species

Abstract

Detailed elemental analysis and low-temperature calorimetric measurement results are reported for the first time for Gram-positive bacteria, Gram-negative bacteria and mold fungi. Microorganism unit carbon formulas (empirical formulas) were calculated. Standard molar heat capacity and entropy were found to be C⁰p,m = 38.200 J/C-mol K and S⁰m = 31.234 J/C-mol K for Escherichia coli, C⁰p,m = 54.188 J/C-mol K and S⁰m = 47.141 J/C-mol K for Gluconobacter oxydans, C⁰p,m = 31.475 J/C-mol K and S⁰m = 33.222 J/C-mol K for Pseudomonas fluorescens, C⁰p,m = 38.118 J/C-mol K and S⁰m = 37.042 J/C-mol K for Streptococcus thermophilus, and C⁰p,m = 35.470 J/C-mol K and S⁰m = 34.393 J/C-mol K for Penicillium chrysogenum. Microorganism heat capacities below 10 K were best described by an expanded Debye-T³ law. Based on the collected data, empirical formulas and entropies per C-mole of the analyzed organisms were determined. The measured heat capacities were compared to predictions of Kopp’s rule and Hurst-Harrison equation, both of which were found to be able to give reasonably accurate predictions. The determined entropies were compared to predictions of Battley and Roels models. The Battley model was found to be more accurate. The measured microorganism entropies lay between the values of their principal macromolecular constituents: DNA, and globular and fibrillar proteins. This indicates that self-assembly of the macromolecular components into cellular structures does not lead to decrease in thermal entropy.