Micro-organisms also known as microbes are microscopic
organisms which can only been seen properly under a microscope. The types of
microbes include bacteria, fungi, viruses and protoctists. Although they can be
harmful, they can be useful when it comes to human existence for example,
saprophytic decomposers are important for breaking down the dead organic matter
found in ecosystems however, they are also involved in food spoilage and
illness. As well as this, bacteria are an essential part of digestion.
Carbohydrate digesting bacteria is found in the gut of mammals. One bacterium
essential to human existence is E-coli found in the large intestine which
provides vitamin K, essential for the clotting of blood.
Micro-organisms are involved in many different cycles and
processes such as the nitrogen cycle. All living organisms require nitrogen to
produce protein. Air contains 80% nitrogen gas however, plants and animals
cannot use it in this form which means that it needs to be converted into
nitrates and is easier for the organisms to absorb. For the nitrogen to be
converted, certain bacterium is needed, these include nitrogen-fixing bacteria,
nitrifying bacteria and denitrifying bacteria. Nitrogen fixing bacteria such as Rhizobium can be found in the soil, nodules and the roots of some
plants (Bothe, et al., 2007). It converts
the gas into nitrogen compounds which are then taken by plants and combined
with the products of photosynthesis to make proteins. Animals receive their protein from other
animals or plants. Nitrifying bacteria converts ammonium compounds found in
waste and dead organic matter into nitrates which are then taken in by plants. Denitrifying bacteria then take the ammonium compounds and
nitrates from the soil and convert them into nitrogen gas (Slade, 2007).
There are multiple factors that can affect the nitrogen
cycle. These factors include intensive farming and lighting. Intensive farming
affects the cycle as it reduces soil quality due to nitrate fertilisers which
strip the essential plant nutrients: nitrogen. Although fertilises improve crop
fields, too much leads to destruction of habitats. The nitrates get washed out
of the soil and flow into lakes and rivers which in turn pollute drinking water
and cause algae to grow in freshwater habitats. The algae use up all the oxygen
which kills the fish and invertebrates (Sprent, 1987).
Not only are bacteria useful for natural processes including
the nitrogen cycle, it is also used for processes such as water/sewage
treatment, food production and pharmaceutical manufacture. Sewage treatment is
the use of bacterium to break down harmful substances by aerobic and anaerobic
bacteria (Bitton, 2011). The aerobic
bacterium decomposes the organic matter in the presence of oxygen and once it
has been used up, the bacterium is not able to function anymore. Anaerobic
bacteria will then continue to decompose the matter into methane and CO2
along with water and other minerals essential to human existence. The ‘sludge’
that is left is used as fertilisers as it is rich in phosphates and nitrates (Mara & Horan, 2003).
Another example of micro-organisms being beneficial to humans
is the use within the food industry. Lactobacillus
feeds on milk and coverts the lactose into lactic acid causing a change in
state during fermentation to produce yoghurt. This is essential to humans as
probiotic yoghurt with live bacteria maintains the balance of microbial flora
in the gut and prevents growth of pathogens (Lee, et al., 2017). As well as this, a type of
fungus known as Fusarium graminearum has
been developed as a meat substitute for humans. Some bacteria and fungi present
in food such as cheese give the products the distinctive flavours such as Penicillium camemberti in the production
Camembert cheese (V, 2015). Yeast is a
common fungus used within the food industry for bread production and brewing.
It breathes anaerobically and can break down the glucose in food with
production of CO2, ethanol and energy. A form of anaerobic
respiration is fermentation in which alcohol is produced.
Pharmaceutical manufacture is another major industry that
uses micro-organisms as they can be beneficial in health and disease. It is
known that antibiotics are acquired from micro-organisms for example, a strain
of fungi is used against another strain to produce a medicine (Hugo & Russell, 2011). They
are also used within vaccines which are partially weakened/killed microbes used
to produces antibodies against antigens that enter the body. One common
micro-organism used in the pharmaceutical industry is Penicillium notatum: the first species of fungus used for medical
purposes. Strains of this fungi are used to produce the drug penicillin (Heritage, et al., 1999)
In conclusion, micro-organisms are essential to human existence
on the planet as they have beneficial uses such as food production and water treatment.
Although a lot of them are pathogenic, there are a lot more that have important
roles within ecosystems and human lives. For example, they are essential for
the nitrogen and carbon cycles and increase crop yields when added to fertilisers.
They are also used within medicines to help produce the antibiotics and are used
for research to determine how to improve the medicine and to determine which micro-organisms
are now antibiotic resistant.