Online Textbook Bacteriology is continuously updated and includes information on Staphylococcus, MRSA, Streptococcus, pseudomonas, anthrax, E. coli, cholera, tuberculosis, Lyme disease and other bacterial pathogens that cause diseases of humans.
Kenneth Todar is the author of the Online Textbook of Bacteriology and an emeritus lecturer at the University of encourages people to wear a FDA approved face mask during the Covid-19 pandemic.
The Online Textbook of Bacteriology is about microbes, including staph, MRSA, strep, anthrax, E. coli, salmonella cholera, pneumonia, meningitis, gastroenteritis, tuberculosis, Lyme disease and other bacterial pathogens.
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Web Review of Todar's Online Textbook of Bacteriology. "The Good, the Bad, and the Deadly"

Tag words: bacteriology, microbiology, bacteria, archaea, procaryote, procaryotic.

Kenneth Todar currently teaches Microbiology 100 at the University of Wisconsin-Madison.  His main teaching interests include general microbiology, bacterial diversity, microbial ecology and pathogenic bacteriology.

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Overview of Bacteriology (page 6)

(This chapter has 6 pages)

© Kenneth Todar, PhD


Exploitation of Bacteria by Humans

Bacteria are used in industry in a number of ways that generally exploit their natural metabolic capabilities. They are used in manufacture of foods and production of antibiotics, probiotics, drugs, vaccines, starter cultures, insecticides, enzymes, fuels and solvents. In addition, with genetic engineering technology, bacteria can be programmed to make various substances used in food science, agriculture and medicine. The genetic systems of bacteria are the foundation of the biotechnology industry discussed below.

In the foods industry, lactic acid bacteria such as Lactobacillus, Lactococcus and Streptococcus are used in the manufacture of dairy products such as cheeses, including cottage cheese and cream cheese, cultured butter, sour cream, buttermilk, yogurt and kefir. Lactic acid bacteria and acetic acid bacteria are used in pickling processes such as olives, cucumber pickles and sauerkraut. Bacterial fermentations are used in processing of teas, coffee, cocoa, soy sauce, sausages and an amazing variety of foods in our everyday lives.

In the pharmaceutical industry, bacteria are used to produce antibiotics, vaccines, and medically-useful enzymes. Most antibiotics are made by bacteria that live in soil. Actinomycetes such as Streptomyces produce tetracyclines, erythromycin, streptomycin, rifamycin and ivermectin. Bacillus and Paenibacillus species produce bacitracin and polymyxin. Bacterial products are used in the manufacture of vaccines for immunization against infectious disease. Vaccines against diphtheria, whooping cough, tetanus, typhoid fever and cholera are made from components of the bacteria that cause the respective diseases. It is significant to note here that the use of antibiotics against infectious disease and the widespread practice of vaccination (immunization) against infectious disease are two twentieth-century developments that have drastically increased the quality of life and the average life expectancy of individuals in developed countries.


The biotechnology industry uses bacterial cells for the production of biological substances that are useful to human existence, including fuels, foods, medicines, hormones, enzymes, proteins, and nucleic acids. The possibilities of biotechnology are endless considering the gene reservoirs and genetic capabilities within the bacteria. Pasteur said it best, "Never underestimate the power of the microbe."

Biotechnology has produced human hormones such as insulin, enzymes such as streptokinase, and human proteins such as interferon and tumor necrosis factor. These products are used for the treatment of a various medical conditions and diseases including diabetes, heart attack, tuberculosis, AIDS and SLE. Botulinum toxin and BT insecticide are bacterial products used in medicine and pest control, respectively

One biotechnological application of bacteria involves the genetic construction of super strains of organisms to perform particular metabolic tasks in the environment. For example, bacteria which have been engineered genetically to degrade petroleum products are used in cleanup of oil spills and other bioremediation efforts.

Another area of biotechnology involves improvement of the qualities of plants through genetic engineering. Genes can be introduced into plants by a bacterium Agrobacterium tumefaciens. Using A. tumefaciens, plants have been genetically engineered so that they are resistant to certain pests, herbicides, and diseases.

Finally, it should not be overlooked that industrial, pharmaceutical and food microbiology are applications of biotechnology. Archaea and bacteria are involved in production of biofuels. Bacteria are the main producers of clinically useful antibiotics; they are a source of vaccines against once dreaded diseases; they are probiotics that enhance our health; and they are primary participants in the fermentations of dairy products and many other foods.

Figure 15. Thermus aquaticus, the thermophilic bacterium that is the source of taq polymerase. L wet mount; R electron micrograph. T.D. Brock. Life at High Temperatures. The polymerase chain reaction (PCR), a mainstay of the biotechnology industry because it allows duplication of genes starting with a single molecule of DNA, is based on the use of the DNA polymerase enzyme derived from Thermus aquaticus.


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Kenneth Todar is an emeritus lecturer at University of Wisconsin-Madison. He has taught microbiology to undergraduate students at The University of Texas, University of Alaska and University of Wisconsin since 1969.

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