HISTORY OF MICROBIOLOGY

Historians are unsure who made the first observations of microorganisms, but the microscope was available during the mid-1600s, and an English scientist named Robert Hooke made key observations. He is reputed to have observed strands of fungi among the specimens of cells he viewed. In the 1670s and the decades thereafter, a Dutch merchant named Anton van Leeuwenhoek made careful observations of microscopic organisms, which he called animalcules. Until his death in 1723, van Leeuwenhoek revealed the microscopic world to scientists of the day and is regarded as one of the first to provide accurate descriptions of protozoa, fungi, and bacteria.

After van Leeuwenhoek died, the study of microbiology did not develop rapidly because microscopes were rare and the interest in microorganisms was not high. In those years, scientists debated the theory of spontaneous generation, which stated that microorganisms arise from lifeless matter such as beef broth. This theory was disputed by Francesco Redi, who showed that fly maggots do not arise from decaying meat (as others believed) if the meat is covered to prevent the entry of flies. An English cleric named John Needham advanced spontaneous generation, but Lazzaro Spallanzani disputed the theory by showing that boiled broth would not give rise to microscopic forms of life.

Louis Pasteur and the germ theory. Louis Pasteur worked in the middle and late 1800s. He performed numerous experiments to discover why wine and dairy products became sour, and he found that bacteria were to blame. Pasteur called attention to the importance of microorganisms in everyday life and stirred scientists to think that if bacteria could make the wine “sick,” then perhaps they could cause human illness.

Pasteur had to disprove spontaneous generation to sustain his theory, and he therefore devised a series of swan-necked flasks filled with broth. He left the flasks of broth open to the air, but the flasks had a curve in the neck so that microorganisms would fall into the neck, not the broth. The flasks did not become contaminated (as he predicted they would not), and Pasteur's experiments put to rest the notion of spontaneous generation. His work also encouraged the belief that microorganisms were in the air and could cause disease. Pasteur postulated thegerm theory of disease, which states that microorganisms are the causes of infectious disease.

Pasteur's attempts to prove the germ theory were unsuccessful. However, the German scientist Robert Koch provided the proof by cultivating anthrax bacteria apart from any other type of organism. He then injected pure cultures of the bacilli into mice and showed that the bacilli invariably caused anthrax. The procedures used by Koch came to be known as Koch's postulates (Figure 1 ). They provided a set of principles whereby other microorganisms could be related to other diseases. 

Figure 1

The steps of Koch's postulates used to relate a specific microorganism to a specific disease. (a) Microorganisms are observed in a sick animal and (b) cultivated in the lab. (c) The organisms are injected into a healthy animal, and (d) the animal develops the disease. (e) The organisms are observed in the sick animal and (f) reisolated in the lab.

THE DEVELOPMENT OF MICROBIOLOGY In the late 1800s and for the first decade of the 1900s, scientists seized the opportunity to further develop the germ theory of disease as enunciated by Pasteur and proved by Koch. There emerged a Golden Age of Microbiology during which many agents of different infectious diseases were identified. Many of the etiologic agents of microbial disease were discovered during that period, leading to the ability to halt epidemics by interrupting the spread of microorganisms. Despite the advances in microbiology, it was rarely possible to render life-saving therapy to an infected patient. Then, after World War II, the antibiotics were introduced to medicine. The incidence of pneumonia, tuberculosis, meningitis, syphilis, and many other diseases declined with the use of antibiotics. Work with viruses could not be effectively performed until instruments were developed to help scientists see these disease agents. In the 1940s, the electron microscope was developed and perfected. In that decade, cultivation methods for viruses were also introduced, and the knowledge of viruses developed rapidly. With the development of vaccines in the 1950s and 1960s, such viral diseases as polio, measles, mumps, and rubella came under control. MODERN MICROBIOLOGY Modern microbiology reaches into many fields of human endeavor, including the development of pharmaceutical products, the use of quality-control methods in food and dairy product production, the control of disease-causing microorganisms in consumable waters, and the industrial applications of microorganisms. Microorganisms are used to produce vitamins, amino acids, enzymes, and growth supplements. They manufacture many foods, including fermented dairy products (sour cream, yogurt, and buttermilk), as well as other fermented foods such as pickles, sauerkraut, breads, and alcoholic beverages. One of the major areas of applied microbiology is biotechnology. In this discipline, microorganisms are used as living factories to produce pharmaceuticals that otherwise could not be manufactured. These substances include the human hormone insulin, the antiviral substance interferon, numerous blood-clotting factors and clot dissolving enzymes, and a number of vaccines. Bacteria can be reengineered to increase plant resistance to insects and frost, and biotechnology will represent a major application of microorganisms in the next century.

WHAT IS MICROBIOLOGY?

Microbiology is the study (logy) of very small (micro) living (bio) things.

Microbiology is the study of microorganisms. These "bugs" include: bacteria (that's the Latin plural for bacterium); viruses (that's the non-Latin plural for virus - virii sounds weird, so I don't say it); and, fungi (that's the Latin plural for fungus - which by now you have guessed, or already knew, and may not be all that interested to know, anyway). Microbiology is actually made up of several sub-disciplines.

Microbiology, one of the fastest growing areas of science, is the study of organisms so small that they must be viewed with a microscope. These organisms are primarily bacteria, yeasts, molds, and viruses. Many of the most important scientific discoveries of recent years have been made by microbiologists: since 1910, one-third of the Nobel Prizes in medicine and physiology have been awarded to microbiologists. They are concerned with the welfare of humankind, concentrating not only on aspects of host-microbial interactions influencing disease and immunity, but also on ecological concerns impacting food production and the environment. There is a great demand for microbiologists. Graduates with a concentration in Microbiology find positions in the areas of medical, agricultural, food, industrial, or pharmaceutical microbiology, or microbial genetics or physiology. They may become teachers, science writers, technical librarians, or managers of scientific companies. Some of these professions require advanced degrees. The concentration in Microbiology is designed to furnish necessary experience in academic and practical skills to prepare graduates for immediate entry into the job market or for continuing graduate education in pure or applied biological sciences.

Microbiology is the branch of science dealing with microorganisms. It is one of the most relevant, dynamic and exciting disciplines in the biological sciences.

Microorganisms benefit society by cycling inorganic and organic matter into molecules needed for life and detoxifying discarded wastes. Historically, they have served as microscopic factories for the production of cheeses, alcohol and antibiotics. Microorganisms have also been engineered to produce a wide variety of products for our benefit through the emergence of biotechnology.

Microorganisms have, however, also inflicted great distress to human, animal and plant populations through disease, spoilage of crops, foods and the fouling and degradation of man-made structures. More recently, microorganisms have been used as terrorist weapons.

Microbiology has become an umbrella term that encompasses many sub disciplines or fields of study. These include:

- Bacteriology: the study of bacteria

- Mycology: fungi

- Protozoology: protozoa

- Phycology: algae

- Parasitology: parasites

- Virology: viruses

An understanding of these various life forms in the environment has created other sub disciplines of: microbial ecology, microbial physiology, microbial genetics and molecular biology. Our need to control infectious diseases has brought about the fields of pathology and immunology. Bioinformatics, the in silico research, is a new area of research in microbiology which analyzes the genomes of life forms.

Microbiology is the study of microscopically small, living organisms, such as fungi, algae, protozoa and bacteria, which require a light microscope for observation, and viruses which are visible only under an electron microscope at more than 20 000x magnification, to increase scientific knowledge and develop medical, veterinary, industrial, environmental and other practical applications. Basic characteristics of the microorganisms, including their form, structure, physiology, growth, reproduction and genetics are studied in courses on mycology, yeast biology, bacteriology and the molecular biology of bacteria, viruses and yeasts. Other courses deal with the composition, activities, ecology, practical importance and control of microbial populations of soil, water, food, plants, human and animal bodies, including disease-producing organisms, as well as industrial microbial fermentations.

Microbiology is the study of all microscopic organisms, principally bacteria, fungi and viruses. Microbiology is one of the foundation biological sciences. Through study of microorganisms has come fundamental understanding of how a cell works. It is also an applied science, helping health and medicine, agriculture and maintenance of the environment, as well as the biotechnology industries. We study microorganisms at the level of the community (ecology and epidemiology), at the level of the cell (cell biology and physiology), at the level of protein and gene (molecular biology). The fusion of these elements is Microbiology.

Microbiology today is an integral part of molecular biology, the study of cellular information, which applies to all of biology. Apparently simple organisms, bacteria and viruses are very important to us. They cause a variety of diseases in humans, animals, and plants. Microbiology has benefited us tremendously in improved health care and agriculture. Through the efforts of microbiologists, diagnosis and treatment of bacterial and viral infections have become effective for most diseases. Bacteria and viruses are also an essential part of genetic engineering which has universal application in biological research and in biotechnology. Bacteria are widely used to produce antibiotics and other chemicals, to generate energy from biomass, and to detoxify environmental pollutants. The Microbiology Option offers a strong science foundation and advanced courses in molecular biology of microorganisms, in microbial diversity, in immunochemistry, and in pathogenic and food microbiology. Many microbiology students graduate with a minor in chemistry although a minor is not required. An in-depth education in microbiology prepares you for academic and industrial research and development in many areas of biology as well as for investigations which focus on specific microorganisms or cellular systems. It also prepares you for advanced study in medicine and clinical microbiology and for graduate study in biology.

Microbiology is the study of microorganisms - specifically, disease-causing microorganisms. Microbiology is responsible for identifying infectious agents in blood, urine, sputum, feces, cerebrospinal fluid, and other body fluids. The infectious agents are then tested for sensitivity to certain antibiotics used to treat infections.

Bacteria are absolutely necessary for all life on this planet - for every known ecosystem - including the human ecosystem! Without bacteria, there would be no life, as we call life, on the earth. However, it is a good thing that most bacteria die-out. Here is why: bacteria are single-cell organisms, that produce more of their kind by cell-division, alone. So, if one begins with a single bacterial cell like E. coli for example, in 20 minutes there will be two, and 20 minutes later, four, etc., E. coli cells. At this rate, even though most bacteria are several hundred-times smaller than we can see with our naked eye (never seen a clothed eye), in only 43 hours, from that one cell at the beginning, there would be enough E. coli to occupy the entire volume of the earth (1,090,000,000,000,000,000,000 cubic meters)! In only about two additional hours, these bacteria would weigh as much as the earth - 6,600,000,000,000,000,000,000 tons! Bummer! Luckily for us, most bacterial cells die because of the enormous competition for food, and because of other tiny organisms which produce substances (antibiotics) that kill them - you know, like penicillin, which is made by a particular fungus, the mold - Penicillium). Thank goodness for that one, huh? Actually, many antibiotics are made by certain bacteria too, and, we get many of our necessary vitamins and nutrients from bacteria by allowing the bacteria to multiply in number, and isolating the things that they make, that we cannot make. For example, amino acid supplements are available ("enriched" bread simply means that the amino acid, lysine, which we absolutely need, but cannot make ourselves, is added to the flour used to make the bread), to provide one additional source which most people will eat. This amino acid is produced by certain bacteria grown in huge vats (can be 20,000 liters at one time - that's about 1,500 gallons!), and purified for our use. Antibiotic production is similarly done.

With the advent of molecular genetics and recombinant DNA technology, bacteria now play a very important role as producers of human substances. Since we have learned how genes function, we are able to introduce a human gene into a bacterium and have the product of the human gene expressed. Consequently, a hormone called erythropoietin, which is absloutely necessary for the proper development of red blood cells (erythrocytes), but very, very, difficult to isolate, is now available in high quantity. People who do not have kidneys cannot make this hormone; however, because the hormone has been cloned into bacteria, plenty of this hormone can be made, purified, and given to these people. Human insulin can be similarly made. These are only two examples of the many substances now available to treat human disorders because of our understanding of bacteria.

Scientists use two names to describe each kind of bacteria. The first is the genus name and second is the species name. When the names of the species and genus are written, the are italicized, or underlined. The genus name usually refers to the group to which the bacterium belongs, somewhat like our human family names, except it is listed first. Many times the genus and species names (in the Latin or Greek language) are selected to describe some general feature of the bacterium. For example, the word used to describe the genus name, Streptococcus, tells us that it is a sphere-shaped cell (coccus) and that it occurs in chains (strepto). The species name is more specific and usually refers to the activity or habit of the organism. The species name lactis tells us that is associated with milk. To illustrate, then, we have the most common bacterium in dairy work: Streptococcus lactis. Once one becomes familiar with the various types of bacteria important to your work, "nicknames" are often used to describe the species of bacteria. For example, Streptococcus lactis becomes "Strept. lactis". If you want to refer to more than one species of bacteria that have some common characteristics, you can use another nickname, like Streps, referring to those several species of bacteria with characteristics like those found in the genus Streptococcus. One nickname commonly used in the dairy industry is E. coli which is short for Escherichia coli. With sometimes difficult names to pronounce, it is no wonder that people prefer bacterial nicknames!