PURPOSE

In this experiment, Saccaharomyces cerevisiae will be cultured on chemically defined medium under aerobic conditions and microbial growth will be followed with indirect and direct methods.

INTRODUCTION

Bioenergetics is the study of the energy relationships in living organisms. Microbial activity is dependent on catabolic reactions for energy production and biomass synthesis (see figure 1).

The relationship between energy and synthesis reactions is critical in understanding the balance of inputs and outputs from the biodegradation process. Bioenergetics provided an analytical framework to combine the stoichiometry of these individual reactions with classical thermodynamics to estimate such important results as cell biomass production and heat evolution. The resultant overall stoichiometric relationships also help determine nutrient requirements, pH and alkalinity effects, and energy flow and fate throughout the system.

In heterotrophic organisms, respiration reactions provide the energy required for cell metabolism and growth. Adenosine triphosphate (ATP) is used by organisms to transfer energy within the cell, and gains this energy during the transfer of electrons from an electron donor to an electron acceptor

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