Bacteriology, the branch of biology devoted to the study of bacteria. Bacteriologists are concerned with the structure and functions of bacteria, with the environmental conditions that affect bacterial growth, with the effects of bacteria on the other organisms, and with the uses for bacteria.

Bacteriology is important in medicine, public health and sanitation work, agriculture, food-processing, and industry. There are many branches of this science, each dealing with special problems that have arisen from the complex effects that bacteria have upon civilization.

The relation of bacteria to disease has given rise to the sciences of pathologic bacteriology (concerning treatment and causes of disease), immunology (concerning immunity to disease), antiseptic surgery, veterinary bacteriology, and sanitary bacteriology.

Plant diseases and their economic importance have led to the development of plant bacteriology. Soil and dairy bacteriology deal with the microorganisms useful in those fields. Zymotechnology concerns fermenting processes caused by bacteria, yeasts, and molds.


The essential tool of the bacteriologist is the microscope. As improved by Anton van Leeuwenhoek (1632–1723), a Dutch lens grinder, it opened up an invisible world on which earlier scientists could only speculate. Leeuwenhoek reported discovery of bacteria in 1676. In 1838, Christian Ehrenberg (1795–1876), a German zoologist, published a work on microscopic organisms. He also developed a system for classifying them, using terms that are still applied by bacteriologists.

Louis Pasteur (1822–1895), a French chemist, is generally considered the father of modern bacteriology. His research on fermentation led to studies of the activity of many microscopic organisms. Robert Koch (1843–1910), a German physician, made major contributions to the techniques of bacteriology. Other important bacteriologists are listed in the following cross references.