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Chapter 3 – Biology and Human Welfare

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Biology and Human Welfare are always associated with each other due to the microbes’ universal nature. Microbes are present in soil, water, air, inside our bodies, and that of other animals and plants, deep inside the geysers (thermal vents), deep in the soil, under the layers of snow several metres, and in highly-acidic environments. Microbes present around us are protozoa, bacteria, fungi and microscopic plant viruses, viroids, and prions. Human health and diseases associated with it result from infection from harmful microbes, or we can say pathogens present in the environment. 

Many microbes in human welfare are involved in assisting humans for better life microbes present in our gut. Microbes present in households are the ones that are easily found at our homes (in the curd, idli, dosa), while microbes in industrial production are those involved in the manufacturing of beverages, bread, and antibiotics. Methanogens are microbes involved in biogas production to generate energy from bio-waste. Some microbes like Rhizobium, Mycorrhiza, Cyanobacteria are involved as biocontrol agents.

An individual’s good health is considered when they demonstrate physical, emotional, mental, and social well-being. When the normal functioning of organs or organ-system is affected, the body of an individual suffers from diseases. 

Diseases can be broadly grouped into types, which are infectious diseases and non-infectious diseases. Some diseases get transmitted from unhealthy people to a healthy person. They are called contagious diseases—for example, common cold, AIDS, chickenpox, etc. If conditions don’t transmit from an unhealthy person to a healthy person, it is termed non-infectious diseases – cancer, diabetes, hypertension, etc.

Many microorganisms present in our environment could cause diseases in man; such disease-causing organisms are called pathogens—for example,  viruses, bacteria, protozoans, fungi, worms, etc. 

Type of DiseasePathogenName of the diseaseMode of transmissionSymptoms
Bacterial diseasesSalmonella typhiTyphoidWater–borne diseaseProlonged high fever (39° to 40°C), weakness, constipation, loss of appetite and headache
Streptococcus pneumoniae and Haemophilus influenzaePneumoniaAir-borne diseaseFever, chills, cough and headache, lips and fingernails may turn grey to bluish in colour in severe cases
Viral diseasesRhino virusesCommon cold
Protozoan diseasesSpecies of Plasmodium (P. vivax, P. malaria and P. falciparum)MalariaVector-borne disease (Female Anopheles mosquito)Chill and high fever recurring after 3-4 days
Entamoeba histolyticaAmoebiasis (amoebic dysentery)Food-borne diseaseConstipation, abdominal pain and cramps, stools with mucus and blood
Diseases caused by wormsAscarisAscariasisWater-borne diseaseInternal bleeding, anemia, muscular pain and fever
Wuchereria (W. bancrofti and W. malayi)Elephantiasis or FilariasisVector-borne disease (Female Aedes mosquito)Chronic inflammation of lymphatic vessels of the lower limbs
Fungal diseasesMicrosporum, Trichophyton and EpidermophytonRingwormsWater-borne diseaseDry, scaly lesions on on skin, scalp and nails

Microbes in human welfare

Not all microbes we come across are harmful. Most of them are useful to humans and plants. They provide us with nutrients, increase the quality, taste and palatability of some food products.

Microbes In Household Products

We use microbes or products derived from them in our lives. Many microbes are used to prepare curd, cheese, fermented fish, soyabean and bamboo shoots to make foods.

  • Lactobacillus – It is commonly called lactic acid bacteria (LAB) and used for production of curd. A small amount of curd which is added to the fresh milk as inoculum, contains millions of LAB. LAB grows in milk at suitable temperatures, produces acids that coagulate and partially digest the milk proteins and convert it to curd.
  • Saccharomyces Cerevisiae – It is commonly known as baker’s yeast. It is added in a dough used to make bread. As a result of fermentation, it releases CO2 and gives a puffed-up appearance to the dough.
  • Propionibacterium Sharmanii – It is used to prepare Swiss cheese.
  • Penicillium Roqueforti – It is a fungi used to prepare a variety of cheese named as Roquefort cheese.

Microbes I Industrial Products

Microbes are used to synthesize a number of products like beverages and antibiotics in the industries. For a long time, microbes, especially yeasts, have been used for the production of beverages such as wine, beer, whisky, brandy or rum. Antibiotics are the chemical substances produced by some microbes that can kill or inhibit the growth of other microbes. Production of these substances on an industrial scale requires growing these microbes in very large vessels called fermenters. Many microbes in industrial products are:

  • Saccharomyces Cerevisiae – It is a fungus which is used to ferment malted cereals and fruit juices to produce ethanol in the industries.
  • Penicillium Notatum – It is a fungus which is used for industrial production of an antibiotic called Penicillin.
  • Aspergillus NigerIt is an acid-producing fungi used in industries for production of citric acid.
  • Acetobacter Aceti – It is a bacteria used to produce acetic acid.
  • Clostridium Butylicum – It is a bacteria used to produce butyric acid in the industries.
  • Lactobacillus – It is a bacteria which is used industrially to produce lactic acid.Many microbes are used to produce enzymes like lipases, proteases, amylases.
  • Lipases – They are used in detergent formulations and remove oily stains from the laundry.
  • Pectinases And Proteases – These enzymes can hydrolyse proteins and thus used to clarify bottled juices.
  • Streptokinase – It is an enzyme produced by the bacterium Streptococcus. It is used to remove clots from the blood vessels of patients who have undergone myocardial infarction.
  • Trichoderma polysporum – It is a fungus used to prepare cyclosporin A that is used as an immunosuppressive agent in organ-transplant patients.
  • Monascus purpureus – It is the statin producing yeast which acts as blood-cholesterol lowering agents. It shows competitive inhibition with the enzyme responsible for synthesis of cholesterol.

Microbes In Production Of Biogas

A mixture of gases produced as a result of metabolic activities inside the microbes is called Biogas. Biogas is used as fuel.

Methanogens are the group of anaerobic bacteria growing on cellulosic material to produce large amounts of methane along with CO2 and H2.  Example – Methanobacterium are present in anaerobic sludge and rumen of cattle. These bacteria hydrolyse the cellulose present in the rumen and provide nutrition to the cattle.

Biogas plant, which is used to produce biogas from the animal excreta, household waste and other bio-waste use these bacteria. The biogas plant consists of a concrete tank which is 10-15 feet deep. Slurry of dung is fed in the tank and bio-wastes are collected. As the methanogens act on the waste, due to their activity, they release gases, hence slurry is produced. Spent slurry is used as fertilizer, while biogas produced is supplied to the nearby houses so that it could be used as fuel and for cooking.

Microbes As Biocontrol \Agents

Most of the plants suffer from many diseases and infections. Such issues can be sorted by using insecticides and pesticides, but they are toxic and extremely harmful to human beings and animals and pollute our environment.

  • Bacillus Thuringiensis – It is a bacteria which is commonly termed as Bt. It is used to control butterfly caterpillars. They are sprayed onto vulnerable plants and then eaten by the insect larvae. Bt contains inactive protein, but when it enters inside the gut of the larvae, the toxin is activated due to pH of the gut and the larvae get killed. The bacterial disease kills the caterpillars, but doesn’t harm other insects. Example- Bt-cotton.
  • Trichoderma – It is free-living fungi found in roots of plants. They act as effective biocontrol agents of several plant pathogens.
  • Baculoviruses– They attack insects and other arthropods, but can be used as biological control agents. Baculovirus is of the genus Nucleopolyhedrovirus. They have species-specific, narrow spectrum insecticidal applications and cause no harm to plants, mammals, birds, fishes or even on non-target insects.

Microbes as biofertilizers

Biofertilizers are produced from the organisms that help in enriching the nutrient quality of the soil.

  • Rhizobium – They are found in symbiotic association with the roots nodules of the leguminous plants. Rhizobium fixes atmospheric nitrogen which is utilised by the plant.
  • Azospirillum and Azotobacter – They are free-living nitrogen-fixing bacteria.
  • Mycorrhiza – They are the fungi which absorb phosphorus from soil and show symbiotic associations with plants.
  • Cyanobacteria – These autotrophic microbes act as important biofertilizers and can fix atmospheric nitrogen. Example – Anabaena, Nostoc, Oscillatoria, etc.

Microbes are a very important component of life on earth. Not all microbes are pathogenic. Many microbes are very useful to human beings. It is clear from the diverse uses human beings have put microbes to that they play an important role in the welfare of human society.

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High School Physics

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  • Addition
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