Microbiology

Microbiology (from Greek mikros-small, bios-life and logos-science), the science studying the smallest organisms or microbes. Microbe-a term proposed by Sedillot for all living beings invisible to the naked eye. Adopting this term, Pasteur named microbie the science of microorganisms. However, the word microbiology gained currency, introduced by Duclaux and applied by him in his treatise on microbes. ("Traite de microbiologie", v. I-IV, P., 1898-1901). The history of M. has common beginnings with bacteriology (see), since the study of microbes as agents of fermentation and infections was created by the discoveries of Pasteur, who, without making a fundamental distinction between yeasts and bacteria, developed methods equally applicable to both. The significance of the simplest organisms (Protozoa) for M. was discovered with the discovery of malaria plasmodia (Laveran; 1882). Ten years later (1892) Ivanovsky found that the mosaic disease of tobacco leaves is caused by an invisible and non-cultivable microbe. In 1896 Loffler and Frosch proved that foot-and-mouth disease has as its agent an invisible and filterable virus. Thus was completed the inclusion in M. of the main types of microbes subject to its study. The content of M. is therefore the study of bacteria, fungi and protozoa by means of special methods developed mainly by bacteriology. However, all the microbes just mentioned are studied by special sciences: bacteria-by bacteriology, fungi-by mycology, protozoan animals-by protozoology. There is also protistology-the doctrine of the lower fungi and protozoan animals standing on the border between the plant and animal kingdoms (kingdom of protists, according to Haeckel). At present the term M. is often (as the name of a subject of instruction, scientific societies, publications and institutions) used either as a synonym for bacteriology or as a concept that, along with bacteriology in its entirety, also includes mycology and protozoology only in a limited part. The existence of separate disciplines for each of the mentioned groups of microbes still does not eliminate the need for M., which combines all these separate disciplines. The point is that the biological role of microbes is extremely great. They participate in a number of the most important processes, in fermentations and infections, which have enormous significance for the life of nature and man. Remarkable in this is that under natural conditions these processes do not depend on the life of only one species of microbe. They, on the contrary, usually proceed under the influence of the joint and sequential activity of different classes of microorganisms. Thus, for example, in the formation of soil, bacteria, actinomycetes (a group transitional between bacteria and fungi), various fungi, yeasts and even unicellular algae and Protozoa participate. Ammonia formation from proteins proceeds very energetically in the soil, and some bacteria play a significant role in this; but fungi also play no less a role. In the decomposition of cellulose, aerobic and anaerobic bacteria, as well as various fungi and actinomycetes, participate. Alcoholic fermentation, on which the production of wine, beer, bread, etc. is based, is caused by various species of yeasts; it can also be caused by various bacteria and molds. In the ripening of cheeses, in addition to lactic and propionic acid bacteria, fungi play a decisive role. Even in a healthy human body, a combination of different species of microbes is observed: bacteria, fungi and protozoa. Some infections are caused by specific combinations of individual species of microbes. In sanitary installations-in the filtration of drinking water, purification of waste water, in the self-purification of rivers-the combined action of various species of microbes is noted. Thus, everywhere in the study of specific processes, the researcher discovers not a uniform flora or fauna, but a landscape inhabited by all classes of microbes. Therefore, for the study of these most important processes, there must exist a science-M., uniting knowledge about all microorganisms. In addition, there are microbes that cannot be confidently attributed to any of the three classes mentioned above, but which must nevertheless be studied in view of their paramount practical importance. Already the genus rickettsiae, among which many authors consider the causative agent of such an important ep. disease as typhus to be found, presents great differences from typical bacteria. Various symbionts of the mycetomas of insects and other animals are even less similar to bacteria. The nature of filterable viruses is still little known, and they play an important role in the etiology, immunology and epidemiology of infectious diseases of man, animals and plants. Finally, there are agents regarding which the question has not yet been decided whether they are living beings or chemical substrates. These are bacteriophage and the causative agent of malignant chicken sarcoma. But they are also studied by the same general methods of M., which were developed with reference to bacteria, and the same problems are raised in connection with them, which constitute the content of M.-Thus the existence of M. as an independent science is fully justified, studying by special methods the corresponding biological phenomena for the solution of its tasks in relation to the totality of all microorganisms, and uniting their various groups-plant, animal and of undetermined origin. The tasks of M. are extremely extensive and diverse, which has led to its splitting into a number of disciplines corresponding to the individual processes to be studied. Thus, medical M. is devoted to the life activity of microbes causing infections in man; veterinary M. deals with microbial diseases of animals; phytopathological M.-microbial diseases of plants; agricultural M. deals with processes occurring in the soil and in cultivated plants (nodules); technical M., which in turn breaks down into many subsections, studies the participation of microbes in various productions: cheese-making, leatherworking, tobacco, brewing, etc.-All these separate disciplines are united by general M., first set forth, as already mentioned, by Duclaux (1898-1901; the work was not completed due to the death of the author). Then general M. was consecutively devoted to the works of Gamaleya (1900), Kruse (1910) and in recent years Omeliansky. - Achievements and prospects of microbiology. In all its subsections M. has led to the most important results and problems. Medical M. has developed the doctrine of infection (see) and has provided means for the prevention and treatment of infectious diseases. In the history of chicken sarcoma it touches on the etiology of malignant tumors. The study of bacteriophages raises before it the question of the elementary properties of living matter. On the other hand, the problems of dissociation and cyclogenesis are introduced into the foundations of the doctrine of the development of organisms. In technical M. there are also many most important achievements. Pure yeast cultures give the desired bouquet to wines and especially a valuable aroma to butter. The study of beer diseases allows their prevention. The discovery of nitrifying and nodule bacteria provides means to increase soil fertility. The production of cheeses is carried out in the desired direction with the help of cultures of corresponding microbes. Further achievements can be expected in questions of the formation of soil humus, the retting of textile plants, in leatherworking, in obtaining high-grade tobacco. Interesting achievements of recent times, showing that microscopic beings can be quickly adapted to meet the increased demand from industry, are glycerin and acetone fermentations. These same examples prove that M. knows how to change the life activity of microbes, directing it in the desired direction. For the study of various departments of medical M. there exist numerous institutes and laboratories both in the USSR and abroad (see Bacteriology). The Pasteur Institute in Paris unites medical, veterinary and agricultural M. (department of soil microbiology in Brie-Comte Robert near Paris). For non-medical disciplines the following institutions exist: in England-laboratory in Rothamsted Park (Harpenden), studying soil M.; in Germany, in Kiel-Preuss. Versuchs- und Forschungsanstalt fur Milchwesen for dairy matters; a similar institute in Switzerland (Rtutti, near Bern); institute of fermentation processes (Gahrungs-gewerbe) in Berlin; a similar institute in Copenhagen (Carlsber Labor.); then a number of marine biological stations studying the microbes of the sea (in England, in the USA). In the USSR, besides the Institute of Experimental Medicine with a department of general M. in Leningrad, there is the Institute of Agricultural M. in the Lenin Agricultural Academy in Moscow; departments of M.: in the Leningrad Ichthyological Institute, in the State Hydrological Institute, in the Meat Institute and generally in almost all technical and agricultural institutes; then the agrobacteriological laboratory of the Institute for Fertilizers; in Kiev-the State Bacteriological Institute named after Zabolotny with a department of soil bacteriology.-Teaching of M. is carried on in medical and technical institutes. The oldest departments of general M. are in Odessa and in Leningrad. Lit.-supplement to the lit. given in the article Bacteriology (vol. II, pp. 712-714). Gamaleya N., Foundations of General Bacteriology, Odessa, 1900; Krichevsky I., Course of Medical Microbiology, pt. 1-2, M.-L., 1930;

Omeliansky V., Fundamentals of Microbiology, M.-L., 1931; Fundamentals of Medical Microbiology, ed. by S. Korshun, vol. I, M.-L., 1930; Khudyakov N., Agricultural Microbiology, M., 1926; Baumgartel, Outline of Theoretical Bacteriology, B., 1924; Bergey D., Manual of Determinative Bacteriology, Baltimore, 1923; Buchanan R., General Systematic Bacteriology, Baltimore, 1925; Buchanan R. and Fulmer E., Physiology and Biochemistry of Bacteria, v. I-III, L.-Baltimore, 1928-30; Calmette A., Negre L. and Boquet A., Technical Manual of Microbiology and Serology, P., 1926 (Russian ed.-M.-L., 1928); Duclaux E., Treatise on Microbiology, v. I-IV, P., 1898-1901; Handbook of Pathogenic Microorganisms, ed. by W. Kolle, R. Kraus and P. Uhlenhuth, v. 1-X. Jena-B.-Wien, 1926-31 (extensive bibliography); Jordan E. and Falk I., The New Knowledge of Bacteriology and Immunology, Chicago, 1928; Kruse W., General Microbiology, Lpz., 1910; Levine M. and Schoenlein H., A Compilation of Micro-organisms, L., 1930; Massee E., Atlas of Microbiology, P., 1915; Marshall C., Microbiology, Philadelphia, 1926; Park W. and Williams A., Pathogenic^Tmicro-organisms, including bacteria and protozoa, Philadelphia, 1929; Waksman S., Principles of Soil Microbiology, London, 1927. See also bibliography for the article Protozoology.