CHAPTER II.

Miscellaneous use of bacteria in the arts.

The foods upon which bacteria live are in endless variety, almost every product of animal or vegetable life serving to supply their needs.  Some species appear to require somewhat definite kinds of food, and have therefore rather narrow conditions of life, but the majority may live upon a great variety of organic compounds.  As they consume the material which serves them as food they produce chemical changes therein.  These changes are largely of a nature that the chemist knows as decomposition changes.  By this is meant that the bacteria, seizing hold of ingredients which constitute their food, break them to pieces chemically.  The molecule of the original food matter is split into simpler molecules, and the food is thus changed in its chemical nature.  As a result, the compounds which appear in the decomposing solution are commonly simpler than the original food molecules.  Such products are in general called decomposition products, or sometimes cleavage products.  Sometimes, however, the bacteria have, in addition to their power of pulling their food to pieces, a further power of building other compounds out of the fragments, thus building up as well as pulling down.  But, however they do it, bacteria when growing in any food material have the power of giving rise to numerous products which did not exist in the food mass before.  Because of their extraordinary powers of reproduction they are capable of producing these changes very rapidly and can give rise in a short time to large amounts of the peculiar products of their growth.

It is to these powers of producing chemical changes in their food that bacteria owe all their importance in the world.  Their power of chemically destroying the food products is in itself of no little importance, but the products which arise as the result of this series of chemical changes are of an importance in the world which we are only just beginning to appreciate.  In our attempt to outline the agency which bacteria play in our industries and in natural processes as well, we shall notice that they are sometimes of value simply for their power of producing decomposition; but their greatest value lies in the fact that they are important agents because of the products of their life.

We may notice, in the first place, that in the arts there are several industries which may properly be classed together as maceration industries, all of which are based upon the decomposition powers of bacteria.  Hardly any animal or vegetable substance is able to resist their softening influence, and the artisan relies upon this power in several different directions.

Benefits derived from powers of decomposition.