THE CHEMICAL 

 ACTIVITIES OF BACTERIA 



CHAPTER I 



BACTERIA AS CHEMICAL AGENTS 



The perceptible environment is composed of atoms, some 

 existing separately, the great majority in constantly changing 

 molecular combinations. The velocities of reaction between 

 these molecular combinations vary over a very wide range and 

 it is probable that only a minute fraction of the chemical 

 changes occurring in the environment are perceived by man 

 since the time for which he can make observations is so short. 

 The chemist makes a study of these changes and endeavours 

 to speed them up in the laboratory by such tricks as raising 

 the temperature, adding strong acids or alkalis, introducing 

 catalysts, etc. But if he studies the world outside his test- 

 tubes and flasks, he soon becomes aware that biological 

 material is able to carry out many types of chemical change 

 with far greater ease and at considerably greater speed than 

 he is able to achieve in his laboratory. In fact, one of the 

 properties which differentiate between living and non-living 

 material is this property of producing rapid and fundamental 

 change in the chemical environment ("metabolism"). 

 Living material is aggregated in organisms and we divide 

 organisms for convenience into macro- and micro-organisms. 

 The term "micro-organism" includes several subclasses such 

 as the unicellular yeasts, protozoa, fungi, bacteria, etc., and 

 it is amongst these organisms that we find the widest range 

 and highest rates of metabolic activities. 



As an index of the rate of metabolism we can take 

 the rate of oxygen consumption which is usually measured 

 as the c.mm. of oxygen taken up per hour by 1 mg. dry 

 weight of cell material and is called the Qog of the cells. 

 If we compare the respiratory activities of various living 



CHEM. A.B. 1 



