BACTERIA AS CHEMICAL AGENTS 



the ribose molecules renders the substance inactive. The 

 power to synthesise proteins, nucleotides, etc, is a property 

 of many living tissues and in some bacteria we have organisms 

 which are able to synthesise all these substances from very 

 simple raw materials and at considerable speed. For example, 

 the group of bacteria known as the chemosynthetic auto- 

 trophes synthesise bacterial protoplasm from purely inorganic 

 sources, utilising COg, NH3, and inorganic salts as the raw 

 material from which is produced all that chemical complex 

 forming the multiplying cell. 



The synthetic abilities of bacteria form an absorbing 

 problem for the chemist, although these abilities are not 

 necessarily exceptional amongst living cells — we do not yet 

 know sufficient about this aspect of metabolism to say how 

 exceptional or unexceptional the synthetic powers of bacteria 

 may be — but when we come to consider the destructive 

 (catabolic) activities of bacteria we are faced with a bewildering 

 diversity of chemical potential. It is common experience 

 that when an organism dies and falls on to the surface 

 of the earth, it will disappear in the course of time. 

 Carcases and corpses are buried, dead plants and plant 

 trimmings are composted, excreta are spread on open fields, 

 and, in due course, they are altered into some form not 

 recognisably related to the original. This is mainly due 

 to the scavenging action of soil micro-organisms which by 

 their destructive abilities break down the dead material and 

 convert it into bacterial protoplasm (fungal protoplasm, etc.) 

 and various soluble products. Think for a moment what this 

 involves: chemically inert proteins such as keratin; poly- 

 saccharide complexes such as chitin and cellulose; fats, 

 hydrocarbons, lipoids, sterols, etc., are broken down into 

 simpler substances which are assimilated, putrefied, or fer- 

 mented, with the resultant production of bacterial protoplasm, 

 salts, ammonia, carbon dioxide, gaseous N2 and H2, etc. 

 Bacteria which can oxidise sulphur to sulphuric acid exist 

 in sulphuretted waters, others exist in soil deriving energy 

 for existence from the oxidation of hydrogen to water, while 



