Introductory Microbiology

Microbiology in 20th Century

• The discovery of microbial effects on organic and inorganic matter started with the discovery of Theodore Schwann and others (1937) who observed that yeast cells are able to convert sugar to alcohol i.e. alcoholic fermentation. It was Pasteur’s observations that revealed about anaerobic and aerobic microorganisms. Role of microorganisms in the carbon, nitrogen and sulphur cycles in soil and aquatic habitats were discussed by Sergei N. Winogradsky (1956-1953) and Martinus Beijerinck (1851-1931), The Russian microbiologist Winogradsky also discovered that

  (i) soil bacteria oxidize Iron, Sulphur and Ammonia to obtain energy,
  (ii) isolated anaerobic N2 fixers and
  (iii) studied the decomposition of cellulosic organic matter.

  On the other hand, Beijerinck, contributed a lot in the area of microbial ecology. Azotobacter, a free living nitrogen fixer was isolated. Later a root nodulating bacterium named as Rhizobium and sulphate reducers were also isolated. Both these microbiologists developed the enrichment culture techniques and the use of selective media in the microbiology.
• In 20th century, microbiology developed from the angle of other disciplines of biological sciences in such a way so that problems of cell structure to the evolution are solved. Although, more emphasis were laid down on the agents of infectious disease, the immune response, chemotherapeutic agents and bacterial metabolism.
• Beadle and Tautam (1941) used mutants of the bread mold, Neurospora while Salvadore Luria and Max Delbruck (1943) used bacterial mutants to show that gene mutations were truly spontaneous and not directed by the environment. Avery, Macleod, and Mc Carty (1944) evidenced that DNA was the genetic carried genetic information. Such discoveries made microbiology, genetics and biochemistry as modern molecularly oriented genetics. Microbiology contributed maximum in molecular biology which deals with the physical and chemical aspects of living matter and its function. The genetic code and the mechanism of DNA, RNA and protein synthesis were also studied by using several microorganisms. Regulation of gene expression and the control of enzymes activity were also discussed in the light of microbiology in 1970’s new discovery such as recombinant DNA technology and genetic engineering were also led to development of microbiology which gave the service of microbial biotechnology.
• Scientists of West C jester University, Pennsylvania have revived a microbe that had been in suspended animation for 250 million years, a remarkable feat which boosts theories that the ancient seeds for life arrived on Earth from space. Russell Vreeland (2003) isolated a spore forming Bacillus sp. From 250 years old sample of salt crystal found below ground (1850 ft.) in New Mexico. The bacterium seems to be similar to Bacillus marismortui. Earlier, there were reports of oldest living creatures of 254-40 million years.