Holiii

teaching triple science quick guide

Micro-organisms in industry

Micro-organisms are used in cheese production.

What are micro-organisms?
Micro-organisms are organisms that are microscopic and cannot be seen by the naked human eye. Fungi, algae, bacteria, protozoa and viruses are all types of micro-organism.

Where can we find micro-organisms?
Where you find water, you can normallyfind micro-organisms. Amazingly, some species have adapted to live in hostile and extreme environments such as the deep sea or geothermal springs.

Facts
Bacteria are small. On average they have diameters of 0.5–2 microns (1 micron is a millionth of a metre). If you lined up 100,000 bacteria of 1 micron in length, the line would only be 1cm long! It is estimated that in the human gut there live1014 microorganisms, which is over 100 trillion organisms. They weigh in at more than 1kg. A 3MW (three million watt) landfill power plant could power 1900 homes, eliminate 6000 tonnes per year of methane from escaping into the atmosphere and eliminate 18,000 tonnes per year of carbon dioxide from fossil fuel replacement. This is equivalent to removing 25,000 cars from the road, or not using305,000 barrels of oil per year.

How are micro-organisms used in industry?
Micro-organisms are essential to many processes. For example, the nitrogen cycle (where nitrogen is recycled in the ecosystem) or in the decomposition of animal and plant waste. Micro-organisms are increasingly important to industry, where they are used in a huge variety of processes ranging from food production to watertreatment. One of the most well-known applications of micro-organisms in industry is fermentation, where carbohydrates (such as sugar) are converted into an acid or an alcohol. Foods that are produced using these methods include cheese, yoghurt, butter, beer, wine and bread. The most common yeast that is used in the preparation of beer is Saccharomyces cerevisiae, commonly known as ‘baker’s yeast’ or‘brewer’s yeast’. Beer is made from barley, wheat or rye grain which is germinated to convert starch to sugar such as maltose. The grain is dried and crushed before hot water and yeast are added to initiate fermentation. In the fermentation process, sugars in the mixture are converted to alcohol and carbon dioxide. After 2–5 days the beer is separated from the yeast, matured and filtered beforeconsumption. Wine is also produced by fermentation. Grapes are crushed to release the sugars, and yeast is then added for fermentation and conversion of the sugars into alcohol. For sparkling wines, the carbon dioxide produced by the fermentation process is trapped to create bubbles.

Terms
Host A host is an organism that harbours a parasite, mutual partner, or commensal partner, typicallyproviding nourishment and shelter. Probiotic Probiotic (for life) bacteria can protect the host and prevent disease. They are live micro-organisms that provide a health benefit to the host. For example, antibiotics can kill off normal intestinal flora and the administration of probiotic bacteria can replenish the flora to normal levels. Fermentation is the chemical conversion of carbohydrates intoalcohols or acids. It occurs when oxygen supplies are limited and therefore is a type of anaerobic respiration.

Yoghurt-based drinks that contain probiotic bacteria (live micro-organisms that can give a health benefit to the host) are increasingly popular. Bacterial strains such as Lactobacillus bulgaricus convert lactose sugar into lactic acid. This lowers the pH and causes the milk to clot,creating the characteristic texture and taste of yoghurt. The live bacteria in probiotic yoghurts are thought to restore the natural microbe population of the gut (flora), which can be depleted by antibiotics, for example.

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