Hello hivers! I hope you're all safe and sound in this pandemic period? This is another educative post that will entice your learning.
Some believed that microorganisms are harmful while some belief that they are of beneficial effect. Some don't even have idea of anything about it not to talk of knowing if it is actually helpful or otherwise. This post will open the eyes of its readers to some certain facts but before then let's look at how microorganism is discovered.
THE DISCOVERY OF MICROORGANISMS
Just as the theory of abiogenesis was being refuted, another controversy on the discovery of microorganisms by Anthony Van Leeuwenhoek. Anthony Van Leeuwenhoek (1632-1723). He developed the curious hobby of constructing microscopes, though he was not the first to build a microscope but his instrument was the finest of that time.
Leeuwenhoek's greatest recognition comes from his discovery of the previously invisible world of microorganisms. He discovered protozoa in fresh water, bacteria in the human mouth. He described his experiments in sufficient details such that it can be repeated.
ECONOMIC IMPORTANCE OF MICROORGANISMS
Microorganisms have both beneficial and harmful impact on man and other living things.
The beneficial effects include;
1.) Microorganisms help in maintaining soil fertility. The activities of saprophytic bacteria and fungi convert dead parts of organism and their waste, into humus which improves soil fertility.
2.) Microorganisms help in maintaining soil fertility. In nature, inorganic substances such as carbon, nitrogen, oxygen, water, phosphates and sulphates, are built up into large organic molecules such as proteins and carbohydrates by various autotrophs including microbial ones. When living organisms die, the elements trapped in these organic compounds are set free, mainly by microbial decomposers, as carbondioxidedioxide, water and ammonia. This is clearly shown by the role played by microorganisms in the nitrogen and carbon cycles.
3.) Saprophytic organisms help in sewage disposal by decomposing sewage into harmless inorganic compounds.
4.) In food industries, microorganisms are used mainly to;
- carry out fermentation
- produce Single Cell Proteins (SCP)
- food additives.
5.) Microorganisms are used in food industries to produce many substances and enzymes of industrial importance e.g. citric acid, dextrans and cellulose.
6.) Enzyme technology - Industries will tend to use microorganisms or their enzymes to bring about chemical conversion.
7.) Genetic Engineering - Microorganisms are used as 'chemical factories' to manufacture substances difficult to obtain by the usual methods.
8.) Biological control of pest - Several microorganisms have been produced to specifically attack insect pests. These pathogens may be added to the crop in powder.
9.) Biodegradation of pollutants - Modern technology produces many organic substances that cannot be degraded and recycled in nature. These substances accumulate and pollute the environment. Petroleum is an important pollutant that is degraded poorly in nature. Hydrocarbons feeding bacteria are used to clean up areas like harbors that become frequently polluted with petroleum.
The harmful effects of microorganisms include;
- Food spoilage microorganisms.
- Disease causing microorganisms.
The important types of disease causing or pathogenic microorganisms in humans are viruses, bacteria, protozoa and fungi. Pathogenic microorganisms cause infections or communicable diseases.
Pathogenic microorganisms generally have a definite path by which they spread which includes:
- Air - Airborne pathogens
- Water - Water borne pathogens
- Food - Food borne pathogens
- Direct skin contact
- Animal vectors
FOOD MICROBIOLOGY
The major preoccupation of all animals has been to obtain food.
We know that microorganisms use the same food that we use so that, for the most part, food preservation involves either killing the microorganisms present on the food or preventing them from growing.
Heating or cooking the food is the major technique for killing contaminating organisms, although the addition of high concentration of salt and use of radiation are also effective for some foods. Food preservation methods that do not kill the organism but work because they prevent their growth include both freezing and drying.
Food Infection: This is the ingestion of food containing living organisms that are able to grow or sporulate in the intestine; causing an illness. Examples of microorganisms causing food infections include Clostridium perfringes, Vibrio parahaemolyticus and a number of different Salmonella Spp.
Food Poisoning:- This is caused by ingesting toxins or poisonous substances that microorganisms have secreted into the food. In food poisoning, the organism may have been killed after formation of the toxin in the food, but if the toxin itself is not destroyed, severe food poisoning can result from eating the food. Organism causing this type of food intoxication include Staphylococcus aureus, Clostridium botulinum and Bacillus ceteus.
Food poisoning due to Staphylococcus aureus is common and usually not fatal. Botulism, the food poisoning caused by Clostridium botulinum toxin, carries a high mortality rate. General control measures for preventing cleanliness and sanitary handling of food, including thorough cooking and refrigeration. Examples of fermented vegetables are green beans, beets, pickles and green olives.
Single Cell Protein (SCP) is the name given to foods consisting solely of yeast, algae or bacteria. They are produced using inexpensive carbohydrate by-products and at present are used primarily as animal foods; although they would appear to provide a good source of proteins and vitamins for humans as well.
CONTROLS OF MICROORGANISMS
To prevent infectious diseases from spreading, we have to kill or inhibit the growth of disease causing microorganisms. This can be done in the following ways:
Sterilization method: This method kill or remove all microorganisms from the objects that are being treated it can be carried out in the following ways.
(a) Moist heat:- Steam under pressure is the sterilizing agent and it is used to sterilize surgical bandages, instrument, media and contaminated materials.
(b) Dry heat:- This is used often to sterilize objects at appropriate temperatures. It is used to sterilize powder gauze dressing, e.t.c
(c) Boiling:- Vegetative forms of pathogenic organisms are readily destroyed at the temperature of boiling water at high temperature, microorganisms can be killed especially by cooking food properly. At low temperature, the growth of microorganism is inhibited e.g. refrigeration r freezingAnticeptics:- These are chemicals that kill or inhibit the growth of pathogenic microorganisms they are usually mild chemicals or dilute solution of strong chemicals that can be safely applied on body surfaces. Antiseptic can be used on cuts, abrasions and wounds on our skin to prevent infection by inhibiting microbial growth. Common antiseptics include alcohol (70%) boric acid and tincture of iodine (2%). Disinfectant are chemicals that kill or inhibit the growth of pathogens - these are stronger chemicals than antiseptics e.g. carbolic acid. It can be used to disinfect lavatories, floors and hospitals.
Antibiotics:- These are chemicals which, in low concentrations, can selectively kill or inhibit the growth of most pathogenic microorganisms. Antibiotics are produced by microorganisms like bacteria and fungi and are not harmful to human. For example, the antibiotic penicillin G is produced by the blue-green mould penicillium.
Generally, antibiotics are used to control diseases caused by pathogenic bacteria. However, they are not effective in controlling pathogenic viruses and protozoa.High Salinity: A high salinity affects the osmotic balance between the microbial cell and its environment. This inhibits the growth of the microbial cell, and so prevent its multiplication. Washing cuts and wound with salt solution prevent them from becoming infected. Some foods are also preserved by salting.
Dehydration:- Water is essential for the growth and multiplication of microorganism. Removal of water or dehydration would, therefore, inhibit microbial growth. Many foods are preserved by dehydration methods such as drying.
Drying in the sun is a practical way of killing disease-causing microorganism in beddings, blanket and clothes. Both dehydration and ultraviolet rays in sunlight kills pathogenic microorganisms.
References
Control of microorganism
Micro organism around us
What is the economic importance of microorganisms?
