Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

When calculating cell-growth thermodynamics, reconsider using the Gibbs free energy equation

10.06.2013
A forthcoming article in The Quarterly Review of Biology provides the basis for an argument against using the Gibbs free energy equation to accurately determine the thermodynamics of microbial growth.

Microbial growth is a biological process that has been previously treated as a chemical reaction operating in accord with the Gibbs free energy equation, developed during the 1870s. The heat of yeast growth was the first to be measured by direct calorimetry, in 1856. However, the full application of the Gibbs equation to microbial growth did not occur until 1997, with the experimental measurement of yeast cell entropy.

Subsequent investigations showed that the quantity of absorbed thermal energy for solid substances had two values, depending on how it was calculated. Because there can be only one correct value at a given temperature, Dr. Edwin H. Battley, emeritus of Stony Brook University and recipient of the International Society for Biological Calorimetry’s Dubrunfaut Award (1994) and Lavoisier Medal (2010), examined the use of the Gibbs free energy equation to accurately determine the change in energy that accompanies cellular growth.

In many systems, the values for some variables cannot be determined experimentally and so must be calculated from theoretically derived values. The free energy change accompanying cellular growth cannot be directly measured but, if the heat of growth can be measured and the entropy change accompanying growth can be calculated indirectly from heat measurements, the free energy change can be calculated using the Gibbs free energy equation.

The basis for Battley’s review is in the observation of an apparent discrepancy between the amounts of growth obtained when S. cerevisiae was grown on glucose in aerobic or anaerobic conditions. Assuming it is the change in the Gibbs energy that drives the reactions that occur in both conditions, it is expected that the amount of growth would be proportional to the amount of nonthermal energy initially available and there would be 13.2 times more growth aerobically than anaerobically. However, when the growth for these two systems was measured turbidometrically, this value was found to be only 3.4. It is clear that a discrepancy exists between what is theoretically expected and what is experimentally determined.

Using results of earlier studies, Battley devised a different equation to calculate the thermodynamics of microbial growth. This involves using a different mathematical procedure to calculate enthalpy values for absorbed thermal energy exchange. As a consequence, values for entropy used for this purpose are removed. He found that the appl­­ication of this equation (which he calls the Battley free energy equation) achieved values different from those obtained using the Gibbs free energy equation for the same system. Because the Battley free energy equation uses an absorbed thermal energy variable that is easier to understand in the context of the real-world system in which microbes exist, Battley argues that his free energy equation more realistically represents real-world conditions, and in a way that is more simple and parsimonious to calculate. As such, it is superior for determining the thermodynamics of microbial growth than is the Gibbs free energy equation.

Battley, Edwin H. “A Theoretical Study of the Thermodynamics of Microbial Growth Using Saccharomyces cerevisiae and a Different Free Energy Equation.” Quarterly Review of Biology Vol.88, No. 2 (June 2013).

The Quarterly Review of Biology (http://journals.uchicago.edu/QRB), the premier review journal in biology, has presented insightful historical, philosophical, and technical treatments of important biological topics since 1926. The QRB publishes outstanding review articles of generous length that are guided by an expansive, inclusive, and often humanistic understanding of biology. Beyond the core biological sciences, the QRB is also an important review journal for scholars in related areas, including policy studies and the history and philosophy of science.

Emily Murphy | EurekAlert!
Further information:
http://www.uchicago.edu

More articles from Life Sciences:

nachricht World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Microscopic trampoline may help create networks of quantum computers

17.07.2018 | Information Technology

In borophene, boundaries are no barrier

17.07.2018 | Materials Sciences

The role of Sodium for the Enhancement of Solar Cells

17.07.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>