BIO 205

Chapter 27

Useful Microbes

Microorganisms in Industry

• Microorganisms Produce Many Useful Organic Compounds

• Primary metabolites are directly involved in normal growth, development, and reproduction.

Many secondary metabolites have value as food additives, pharmaceuticals, vitamins, etc.

• Secondary metabolites have important ecological functions, and are often species specific.

Microorganisms Also Produce Important Enzymes and Other Products

Some enzymes are important commercially, such as:

1. amylase2. pectinase3. several proteases

Streptokinase breaks down blood clots formed during a heart attack

Hyaluronidase facilitates absorption of fluids injected under the skin

Lactones produced by species of fungi are used for flavorand aroma enhancement

Beer Is Produced by the Fermentation of

Malted Barley

Wine Is Produced by the Fermentation of Fruit or Plant Extracts

Fruit or plant materials are crushed to produce juice (must)

Yeasts are added to begin fermentation in anaerobic conditions

The wine is aged in wooden casks, where unique flavor and aromas develop based on:

• yeast• cask wood• organic compounds in the fruit/plant

• Distilled Spirits Contain More Alcohol than Beer or Wine

• Ethyl alcohol results from distillation of fermented fruits or grains

Other Microbial Products

Many Antibiotics Are the Result of Industrial Production

Penicillin was the first antibiotic to be produced on an industrial scale

Antibiotic production can involve fermentation, producing natural antibiotics or semisynthetic drugs

S. griseus

Some Microbial Products Can Be Used to Control Insects

• A microbial toxin insecticide should be quick and specific to an insect pest

• Bacillus thuringiensis produce a toxin (Bt-toxin) during sporulation that is deposited on leaves

• If ingested by caterpillars, the toxin lyses the gut wall causing paralysis and bacterial invasion

• It seems to be harmless to plants and humans

B. thuringiensis

Dead Cabbage Butterfly Larva

• Fungal Organisms Also Are Being Commercially Developed

• Yeast cells are grown in fermentors

• They are sold as dry yeast or compressed yeast cakes

• Many species of mushrooms are grown on farms

• High humidity and cool temperatures are required for mushroom growth

Agaricus bisporis

Bioremediation Helps Clean Up Pollution Naturally

Naturally occurring Pseudomonas species can be stimulated to degrade oil in spills

Species of Arthrobacter degrade oil and allow plant growth in spill regions

Exxon Valdvez

Anaerobic and aerobic bacteria can reduce polychlorinated biphenyls (PCBs) to:

• carbon dioxide• water• hydrogen chloride

Bacteria can degrade trichloroethylene (TCE) in contaminated ground water

Deinococcus radiodurans may be used to clean up:

• radioactive waste • ionic mercury compounds

Bacteria can reduce levels of TNT in soil surrounding weapons plants

• Industrial Genetic Engineering Continues to Make Advances

• Bacterial plasmids can be used to transfer a foreign gene into a targeted bacterial cell

• Traits like antibiotic resistance and antibiotic production can be transferred

Plasmids

Scientists hope to insert genes from Rhizobium into grain plants, removing the need for fertilizer

Biotechnology may also be used to disrupt pathogen life cycles to prevent disease

End of Chapter 27