Microorganisms: Man and his health
According to lamlad biology pdf download, microorganisms are microscopic living organisms that are typically not visible to the naked eye but can be seen with a microscope. The microorganisms include bacteria, viruses, protozoa, algae and fungi.
Microorganisms Around us
Microorganisms are found almost everywhere in nature. They are found in water, soil, air, surfaces of objects and living organisms, within living organisms where they can invade living cells.
Many microorganisms are disease-causing agents known as pathogens and are mainly parasitic microorganisms. Some microorganisms benefit man, especially the saprophytic ones that bring about the decay of organic matter.
Micro-organisms can be grouped as follows:
- Those without cell structure comprise all viruses.
- Those with prokaryotic cell structures comprising all bacteria and blue-green algae, and Those with eukaryotic cell structures comprising all protists, certain fungi and algae.
Microorganisms in Air
Microorganisms do not grow in the air but occur in dust and water droplets. They produce spores which are light and can be easily dispersed by air. When the spores land on suitable substrates, they germinate, multiply and produce more spores.
Nutrient agar which is exposed to air, grows various types of colonies of bacteria and fungi. The common micro-organisms found in the air are as follows:
- Virus: Common cold virus, influenza virus, poliovirus, pox virus and measles virus.
- Bacteria: Pneumococci, Staphylococci, Streptococci, and Bacillus anthracis cause anthrax and Mycobacterium tuberculosis cause tuberculosis.
- Fungi: Penicillium (blue-green mould), Aspergillus, Rhizopus nigricans (black or bread mould), Saccharomyces (yeast).
Microorganisms in Water
Aquatic organisms are rich in both organic and inorganic nutrients. Marine environments such as wells, ponds, lakes, streams, rivers and seas support various bacteria, blue-green algae, protists, green algae and fungi. Plankton is common microorganisms that constitute aquatic water bodies.
Microorganisms found in water can be grouped as follows:
- natural water microorganisms
- soil microorganisms
- sewage microorganisms
The natural water microorganisms comprise bacteria: Coccus, Bacillus, Pseudomonas, Azoto-bacteria, Thiobacillus, Sarcina, Micrococcus, Vibrio, Spirillum and Spirochaeta which are mostly hetero-trophic.
The blue-green algae include Oscillatoria, Nostoc and Anabaena.
The protists include autotrophic diatoms, dinoflagellates, Chlorella, Chlamydomonas and certain species of Euglena and heterotrophic Amoeba and Paramecium.
The Algae include green algae such as Spirogyra and Volvox. These green algae and protists, such as diatoms, are the primary producers in aquatic environments.
The fungi comprise aquatic fungi, moulds and mildews.
These comprise nitrifying and nitrogen-fixing bacteria, Streptomyces and certain fungi. More information can be read about soil microorganisms when you download lamlad biology pdf.
These include coliform microorganisms such as viruses and non-pathogenic bacteria e., g. Escherichia coli, Streptococcus, Enterococcus faecalis, pathogenic bacteria such as Vibrio cholera and Salmonella Typhi and pathogenic protozoa such as Entamoeba histolytica all of which are found in the intestine of vertebrates.
Microorganisms in our Bodies and Food
Normal Microform in the Body
Microorganisms colonize infant bodies shortly after birth. At the adult stage, numerous bacteria, yeasts and protozoa are established on and in the body. These normal microflorae prevent or interfere with the invasion of the body by pathogens. They become pathogenic when the host’s resistance becomes low, e.g. E. col/, usually found in the colon and causes urinary tract infections.
Pathogenic Microorganisms in the Body
Pathogenic microorganisms usually establish themselves in human bodies and cause diseases:
- When the body resistance is low
- When the normal microflora in the body is disrupted by antibiotic therapy, and in infants where the normal microflora is not yet established.
The inability of the body to resist or fight against pathogens is caused by the following:
- malnutrition, stress and overwork
- Harmful habits like smoking and drinking, and environmental pollution.
Carriers of Microorganisms
The non-living agents that carry microorganisms from one place to another are air, water and food. The living agents that carry microorganisms from place to place are animals. These animals that carry pathogenic microorganisms are known as Vectors.
These vectors include insects like mosquitoes, houseflies, cock-roaches, fleas and tsetse-flies, and other animals like rats, dogs and cats.
Microorganisms in Action
The effects of microbial activity can be seen in the form of organic decay and infectious diseases. The activities of microorganisms can, however, be seen in food production, industrial processes, medicine, agriculture, water treatment and waste disposal.
Beneficial effects of microorganisms
The beneficial effects of microorganisms are seen as primary producers. Microorganisms are also used in various ways to benefit mankind. The use of biological organisms in industries is known as biotechnology. This may involve the use of microorganisms or the use of enzymes extracted from microorganisms.
Beneficial effects in nature
- Microorganisms play an important role in maintaining soil fertility, and recycling nutrients in the ecosystem
Saprophytic microorganisms decompose sewage into harmless inorganic compounds. This is effective in sparsely populated areas. Aerobic and anaerobic bacteria act upon sewage in sewage treatment plants in cities. The final harmless liquid is discharged into water bodies while the sludge is used as fertilizer.
Micro-organisms are used in food industries mainly to:
- Carry out fermentation on certain edible substances to produce foods with properties that help to preserve them, have improved flavours and textures, and make them easily digestible.
- Produce single cell proteins (SCP) from bacteria, yeasts and blue-green algae for cattle feed and human food; and
- Food additions such as vitamins, amino acids and nucleotides are produced from microbial cultures.
Microorganisms are used to produce many substances and enzymes of industrial importance, such as citric acid, dextrans and cellulose. They are also used to produce substances that are important in medicine, such as antibiotics, steroid hormones and vaccines. Bacteria are being used to extract metals such as copper and uranium from low-grade ore and waste residue from mines.
With the use of genetic engineering techniques, scientists are able to produce microorganisms which act as. “*chemical factories** and manufacture substances difficult to obtain by the usual means.
Harmful effects of Microorganisms
Microorganisms are harmful in two ways: by causing food spoilage and by causing diseases.
The types of disease-causing or pathogenic microorganisms in humans are viruses, bacteria, protozoa and fungi.
Spread of Disease-causing microorganisms
Pathogens can spread through:
- Air airborne pathogens entering through the nose or mouth cause diseases like pneumonia, tuberculosis, influenza and mumps.
- Water by water-borne pathogens, spread by drinking contaminated water, affecting the intestines of the host and causing diarrhoea, typhoid and cholera.
- Food by food-borne pathogens through the eating of contaminated food such as milk and ice cream causes bacillary dysentery, amoebic dysentery and cholera.
- direct skin contact, especially in crowded places or during kissing or sexual intercourse and may cause leprosy, ringworm, yaws, syphilis and gonorrhoea; and
- Animal vectors such as insects can spread disease-causing organisms from person to person.
Towards Better Health
In order to attain better health, there is a need to control disease-causing microorganisms and their animal vectors and improve public health facilities.
Control of harmful microorganisms
In order to prevent the spread of infectious diseases, there is a need to kill or inhibit the growth of disease-causing microorganisms. This can be done as follows:
- Sterilization methods kill or remove all microorganisms from the objects that are being treated by using high temperatures and sterilizing chemicals like chlorine.
- Use of chemicals like disinfectants, antiseptics and antibiotics to kill or prevent the growth of pathogenic microorganisms.
- Use of preservation techniques to prevent food spoilage and growth of pathogens in medicines. Use of high salinity salt solution to wash cuts and wounds to prevent them from becoming infected.
- Removal of water or dehydration to inhibit microbial growth.
Control of Vectors
Important vectors of diseases are insects and rodents. The insect vectors include mosquitoes, houseflies, tsetse-flies, lice, and fleas. Through the knowledge of their habits and life cycles, environmental, biological and chemical methods can be used to control a given vector.
The maintenance of good public health in a nation would require the following:
- refuse and sewage disposal;
- protection of water supply and provision of clean water;
- food hygiene;
- control of discases;
- and healthy organizations.
Public Health Organisations
- Family Health International (FIH)
- Federal Environmental Protection Agency (FEPA)
- Global Health Council (GHC)
- Global Health Watch (GHW)
- International Planned Parenthood Federation (IPPF)
- National Institute of Public Health (NIPH)
- National Institute of Health (NIH)
- United Nations Children’s Fund (UNICEF)
- World Health Organization (WHO).