Economic importance of bacteria
The economic importance of bacteria derives from the fact that bacteria can be deliberately exploited by humans in a number of beneficial ways.  Despite the fact that some bacteria play harmful roles, such as causing disease and spoiling food, the economic importance of bacteria includes both their useful and harmful aspects.

# Useful bacteria
Most bacteria are
'Bold text'Bold text'===Biotechnology and bacteria===
Biotechnology is defined as the application of organisms such as bacteria, fungi and algae to the manufacturing and services industries. These include:
- Fermentation processes, such as brewing, baking, cheese and butter manufacturing, Bacteria, often Lactobacillus 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 yogurt.
- Chemical manufacturing such as ethanol, acetone, organic acid, enzymes, perfumes etc.  In the chemical industry, bacteria are most important in the production of enantiomerically pure chemicals for use as pharmaceuticals or agrochemicals.
- Pharmaceuticals, such as antibiotics, vaccines and steroids.
- Microbial mining, which is the bacteria and other microorganisms are cultured in container and then used to bring these processes e.g., copper extraction.

## Genetic engineering and bacteria
Genetic engineering is the manipulation of genes. It is also called recombinant DNA technology. In genetic engineering, pieces of DNA (genes) are introduced into a host by means of a carrier (vector) system. The foreign DNA becomes a permanent feature of the host, being replicated and passed on to daughter cells along with the rest of its DNA.  Bacterial cells are transformed and used in production of commercially important products. The examples are production of human insulin (used against diabetes), human growth hormone (somatotrophin used to treat pituitary dwarfism), and infections which can be used to help fight viral diseases.
Using biotechnology techniques, bacteria can also be bioengineered for the production of therapeutic proteins, such as insulin, growth factors or antibodies.

## Fibre retting
Bacterial populations, especially that of Clostridium butyclicum, are used to separate fibres of jute, hemp, flax, etc, the plants are immersed in water and when they swell, inoculated with bacteria which hydrolyze pectic substance of the cell walls and separate the fibres.These separated fibres are used to make ropes and sacks.

## Digestion
Some bacteria living in the gut of cattles, horses and other herbivores secrete cellulase, an enzyme that helps in the digestion of the cellulose contents of plant cell walls.  Cellulose in the major source of energy for these animals.

## Vitamin synthesis
Escherichia coli living in human colon synthesize vitamin B and release it for human use. Similarly, Clostridium butyclicum is used for commercial preparation of riboflavin, a vitamin B.

## Waste disposal
Aerobic and anaerobic bacteria are used to decompose sewage wastes. They break down organic matter to harmless, soluble sludge in settling tanks. The methane gas produced is used as energy source. Similarly toxic chemicals synthesized by living organisms and those present in the pesticides are disposed with the help of bacteria.
Pseudomonas putida has been created by using genetic engineering techniques and can break down xylene and camphor.
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. Fertilizer was added to some of the beaches in Prince William Sound in an attempt to promote the growth of these naturally occurring bacteria after the infamous 1989 Exxon Valdez oil spill. These efforts were effective on beaches that were not too thickly covered in oil. Bacteria are also used for the bioremediation of industrial toxic wastes.

# Pest control
Bacteria can also be used in the place of pesticides in the biological pest control. This commonly uses Bacillus thuringiensis (also called BT), a Gram-positive, soil dwelling bacterium. This bacteria is used as a Lepidopteran-specific insecticide under trade names such as Dipel and Thuricide. 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.

# Harmful bacteria
Some bacteria are harmful and act either as disease-causing agents (pathogens) both in plants and animals, or may play role in food spoilage.

## Agents of disease.
Organisms which cause disease are called pathogens. Some bacteria are pathogens 
Some bacteria are pathogenic and cause diseases both in animals and plants. However, pathogenic bacteria more commonly affect animals than plants.

## Food spoilage
Saprotrophic bacteria attack and decompose organic matter. This characteristic has posed a problem to mankind as food such as stored grains, meat, fish, vegetable and fruits are attacked by saprotrophic bacteria and spoiled. Similarly milk and products are easily contaminated by bacteria and spoiled.