GENERAL MICROBIOLOGY - T.P. Pyrog - 2004

1. EMERGENCE AND DEVELOPMENT OF MICROBIOLOGY

1.3. ROBERT KOCH'S DISCOVERIES. DEVELOPMENT OF RESEARCH METHODS

The establishment of MICROBIOLOGY AS A science is largely associated with the name of the German scientist Robert Koch (1843-1910). Having conducted initial experimental studies on mice, he discovered the CAUSATIVE AGENT OF anthrax — a spore-forming rod bacterium. The scientist proved that the disease can be caused by both vegetative Cells and spores. In 1882, R. Koch discovered the causative agent of tuberculosis — the tubercle bacillus. From a culture of the tuberculosis bacillus grown on a liquid nutrient medium, he obtained a preparation called tuberculin, which is still used today for diagnosing tuberculosis. For these studies, R. Koch was awarded the Nobel Prize (1905). During an expedition to Egypt and India to combat cholera, he discovered the cholera vibrio.

In R. Koch's time, laboratory Methods for working with microorganism cultures had not yet been developed. To obtain pure cultures, the dilution method proposed by R. Koch was used. The fluid containing a mixture of microorganisms was repeatedly diluted with sterile Water in order to isolate a single microbial Cell at a certain dilution. However, this labor-intensive method could not reliably guarantee obtaining a pure culture.

In R. Koch's laboratories, METHODS FOR PREPARING solid nutrient media using gelatin were developed for the first time. On such a solid medium, microorganisms grow as isolated colonies, with each colony consisting of cells of a single species, thus representing a pure culture. Later, R. Koch's laboratory began using Agar instead of gelatin for preparing solid media — a polysaccharide extracted from red seaweeds. Its solutions melt at 100 C and turn into a solid, transparent gel at 44 C. The scientist's laboratory also developed Methods for Staining microorganisms with aniline Dyes, designed a Microscope illuminator, applied an immersion system, and developed a technique for bacterial microphotography.