IGCSE topic 35: Industrial uses of microorganisms

Aerobic

Requires oxygen.

Aerobic respiration

Process by which substrates are oxidised to carbon dioxide and water in order to release energy for cells.

Anaerobic

Can occur in the absence of oxygen.

Ethanol

A product of anaerobic respiration in yeast that is particularly important in the production of beers and wine.

Fermentation

Growth of microorganisms in a large fermenter vessel. Also refers to the production of ethanol by anaerobic respiration using yeast or bacteria.

Fermenter

A large glass or stainless steel vessel used to grow large volumes of microorganisms under carefully controlled conditions.

Lactic acid bacteria

Bacteria that ferment the lactose in milk to form lactic acid. Used in the manufacture of cheese and yoghurt. Examples include lactobacillus and streptococcus.

Lactose

A simple sugar that is found in milk.

Oxygen

Gas required by most living things. Allows energy to be released from food molecules by the process of aerobic respiration.

Yeast

A simple single-celled fungus that is used in brewing and bread making.

Yoghurt

Dairy product produced by fermenting milk with bacterial cultures to produce lactic acid.

Enzyme

A protein molecule that can catalyse a chemical reaction due to the precise shape on its surface known as the active site.

Amylase

Enzyme that is responsible for the break down of starch molecules. Found in saliva.

Binary fission

Type of asexual reproduction where cell divides to give two identical daughter cells.

Tissue culture

Growing plant or animal cells in liquid culture in the laboratory under aseptic conditions

Antibiotic

A chemical drug that can kill bacteria or stop them from growing but that is safe to use in people or animals.

Antibiotic resistance

Genetic changes caused by rare mutation, that cause some bacteria to become unaffected by specific antibiotics.

Bacterium (bacteria)

One of the five kingdoms of life. Type of microorganism without a nucleus or any membrane-bound organelles. Many types can cause disease.

Biotechnology

The use of microorganisms to produce useful products or carry out useful processes.

Insulin

The important hormone produced by the pancreas that lowers blood glucose levels.

Exponentially

An increase in a factor where the rate of increase itself increases with time

Fertiliser

An additive used to enrich soil in essential plant minerals

Alginate beads

A simple way of immobilising enzymes or microorganisms using a polysaccharide derived from seaweed.

Barley

Source of carbohydrate used in the fermentation process that produces beer.

Death or decline phase

When bacteria are no longer dividing. The death rate significantly exceeds any growth.

Distillation

The process of concentrating alcohol by heating the products of yeast fermentation and condensing the most volatile products.

Food preservation

Preventing or slowing the decay of food by decomposers through artificial means

Homogenisation

Very thorough mixing process that disperses the fat globules in milk.

Hops

Type of dried flower that is added to beer to give more flavour.

Lag phase

When bacteria are adjusting to the new conditions by synthesising the enzymes they need for growth.

Log or exponential phase

When bacteria are dividing rapidly by binary fission. Bacterial numbers double in a fixed period.

Malt

Mixture of starch and sugars produced by germinating barley. Used in beer production.

Malthouse

Flat surface where barley is spread out to germinate and produce the malt.

Mash tun

Vessel used in brewing where the starch in the malt is converted into maltose.

Pasteurisation

Flash heating milk or other liquid foods such as beer to about 80 degrees C for 15 seconds to kill most potentially harmful bacteria or prolong shelf-life.

Penicillin

An important class of antibiotic, the first to be isolated, that kills bacteria by interfering with the synthesis of their cell walls. Produced by a type of mould called penicillium.

Penicillium

Name of the mould that produces the antibiotic penicillin.

Stationary phase

When bacteria are running out of nutrients and toxic products are accumulating. The death rate equals the growth rate.

pH

A measure of the acidity (hydrogen ion concentration) of a solution.

Temperature probe

Sensor used to monitor the temperature in a fermenter.

Homogenisation

Process in which milk is mixed vigourously to ensure that all the fat droplets are fully dispersed.

Starter culture

Flask containing microorganisms that have been grown under carefully controlled conditions to inoculate a larger fermentation vessel.

pH probe

Sensor used to measure the acidity in a fermentation vessel so that conditions can be controlled by the addition of acid or base.

Water jacket

Hollow wall surrounding a fermenter that allows cooling or heating water to be pumped through to control the temperature of the fermentation.