Bacteria are a large group of single-celled micro-organisms found everywhere on Earth. Several thousand species exist but only a hundred have economic importance. They are vital to life, performing many physiological functions, including metabolic functions to complete the fermentation of nutrients, barriers functions to protect the digestive system from pathogenic bacteria and stimulation functions in the development of the immune system. There are approximately ten times as many bacterial cells in the human flora as there are human cells in the body, with large numbers of bacteria on the skin and as gut flora. Most bacteria have not been characterized, and only about half of the phyla of bacteria have species that can be grown in the laboratory.
Bacteria grow to a fixed size and then reproduce through binary fission, whereby they divide the genetic information and split into two new organisms. Under optimal conditions, they can grow and divide extremely rapidly, and bacterial populations can double as quickly as every 9.8 minutes. In an industrial setting, bacteria are cultivated in fully aseptic conditions. Bacterial cell biomass inoculum is prepared in the laboratory, and then transferred to industrial fermenters. Parameters of fermentation (pH, Temperature, aeration) may vary depending on the strains used. The growth media can be either multiple ingredients and in some cases dairy based ingredients. After growth, the cells are harvested through centrifugation, then either frozen or lyophilized for packaging and sale. Dry bacteria can be sold as a bulk powder or dosage form (capsule or sachet).
Bacteria, often lactic acid bacteria such as Lactobacillus and Lactococcus, in combination with yeasts and molds, have been used for thousands of years in the preparation of fermented foods such as cheese, pickles, soy sauce, sauerkraut, vinegar, wine and yoghurt.
Some bacteria ferment in the gastro-intestinal system helping the host digest foods and fight off opportunistic pathogens. The choice of functional bacterial strains used as probiotics is based on many scientific criteria, including their ability to promote health, their safe use in food, their suitability for large-scale industrial production, their survival and metabolic activity under processing and storage conditions, and during their passage through the digestive tract.
The ability of bacteria to degrade a variety of organic compounds is remarkable and has been used in waste processing and bioremediation. Bacteria capable of digesting the hydrocarbons in petroleum are often used to clean up oil spills. Bacteria are also used for the bioremediation of industrial toxic wastes. In the chemical industry, bacteria are most important in the production of enantiomerically pure chemicals for use as pharmaceuticals or agrichemicals.
Bacteria can also be used in the place of pesticides in the biological pest control. Because of their specificity, these pesticides are regarded as environmentally friendly, with little or no effect on humans, wildlife, pollinators and most other beneficial insects.
Because of their ability to quickly grow and the relative ease with which they can be manipulated, bacteria are the workhorses for the fields of molecular biology, genetics and biochemistry. By inducing mutations in bacterial DNA and examining the resulting phenotypes, scientists can determine the function of genes, enzymes and metabolic pathways in bacteria, and then apply this knowledge to more complex organisms. This understanding of bacterial metabolism and genetics allows the use of biotechnology to bioengineer bacteria for the production of therapeutic proteins, such as insulin, growth factors, or antibodies.