Commercial Uses of Microorganisms PDF

# Commercial Uses of Microorganisms ## Fermentation - Fermentation is the breakdown of substances by the activity of fungi and bacteria, usually leading to the production of carbon dioxide and alcohol/acid. - Alcohol is made by the fermentation of sugar using yeast. - Yeast is used to ferment suga...

# Commercial Uses of Microorganisms ## Fermentation - Fermentation is the breakdown of substances by the activity of fungi and bacteria, usually leading to the production of carbon dioxide and alcohol/acid. - Alcohol is made by the fermentation of sugar using yeast. - Yeast is used to ferment sugars in grapes to make wine. - Sugars in rice and barley are fermented to produce beer. ## Commercial Uses - **Yeast is used in bakeries to make bread.** When it is added to dough, it produces carbon dioxide, which makes the dough rise. Bread made from the dough is soft and fluffy due to the gas. Yeast is also used to make dhokla light and fluffy. - **Idli and dosa are made by grinding rice and pulses to a fine paste.** The mixture is allowed to stand for a few hours. Fermentation occurs naturally due to bacteria in the mixture. # Retting of Fibres - Linen is made from fibres obtained from the flax plant. - Similarly, jute fibres are obtained from jute plants. - The plants are tied in bundles and placed in water. - Bacteria enter the stems and gradually destroy the stem tissues, loosening the supporting fibres. This is known as **retting**. - These fibres are used to make threads. # Production of Leather - The action of microbes was traditionally used in the leather-making industry. - During the processing of hide (animal skin) to produce leather, the action of bacteria on the skins makes them soft and pliable. # Food Industry ## Making of Curd and Cheese - Some bacteria break down lactose (milk sugar) to form lactic acid, which turns milk sour. - Lactic acid acts on **casein**, a protein present in milk. - This helps in the formation of curd. ## The Making of Cheese - The making of cheese is similar in some ways. - Bacteria convert the lactose found in milk to lactic acid. - An enzyme is added to set the curd. - The semi-solid curdled material is separated from the fluid and is made into cheese. - Fungi and bacteria act on fresh cheese and give it its characteristic smell and flavour. ## Making of Vinegar - Yeast cells break down the sugar found in fruits and convert it into alcohol. - Bacteria act on this alcohol to form vinegar. # Algae - Algae are used in the preparation of agar (vegetarian gelatine). - Sodium compounds obtained from algae keep ice cream smooth and free of crystals. - Products from algae are also used as food stabilisers and as a thickener in salad dressings. - Algae are potentially an unlimited source of wholesome and nutritious food. - In China and Japan, many types of seaweed are consumed as food. - Chlorella is a single-celled spherical alga that has been the subject of research in the study of photosynthesis and as a source of human food (especially on space flights). # Making of Antibiotics - An **antibiotic** is a substance that kills microorganisms or stops their growth. - Fungi secrete antibiotics such as penicillin and cephalosporin, while bacteria secrete the antibiotics streptomycin, chloramphenicol and tetracycline. - Antibiotics can kill disease-causing microorganisms without severe side effects such as injury to body tissues or disturbance of body functions. - Today, over a hundred different antibiotics are available to doctors to cure anything from minor illnesses to life-threatening infections. - Each antibiotic works differently and acts on different types of bacteria. - Antibiotics are also used to cure plant and animal diseases. - They are mixed with food to cure microbial infections in livestock (poultry and cattle). # Immunity and Making of Vaccines - A foreign substance or a disease-causing microbe that enters our body is called an **antigen**. - Our body produces proteins, called **antibodies**, to attack and destroy the antigen. - Antibodies produced against a particular antigen are specific and will attack only that antigen. - For example, antibodies produced against the measles virus will not attack typhoid bacteria. - The ability of our body to resist infection is known as **immunity**. - **Immunity against some diseases may be natural, that is, inherited from parents.** - **Immunity against some diseases is acquired after recovering from an attack of the disease, as in the case of measles and chickenpox.** - Once you have recovered from these diseases, the antibodies remain in the blood for a short time. - However, the ability to produce the antibodies again is greatly increased. - Therefore, any further infection by the bacterium or virus is likely to be stopped, and you are immune to the disease. - **Immunity against a particular disease can also be induced in the body by introducing dead or weakened microbes of the disease.** - This substance introduced into the body is called a **vaccine**. - The body recognises the antigen and produces antibodies against it. - This technique is called **vaccination** or **immunisation**. - Through this process, it is now possible to be protected against a number of infectious diseases like tetanus, typhoid, polio, measles and hepatitis B. ## Vaccines - Vaccines can be a dose of: - **dead microbes**, as in the case of cholera and typhoid vaccines - **live microbes**, which have been altered so that they are no longer dangerous and cannot cause the disease, as in the case of polio and measles vaccines - **toxoids**, harmless forms of the **toxins** (poisonous substances) produced by disease-causing germs, as in the case of the tetanus vaccine - All vaccines are made from microorganisms. # Harmful Microorganisms - Many kinds of microorganisms cause diseases in humans. Such microorganisms are called **pathogens**. - Diseases caused by microorganisms and transmitted from an infected person or animal to another person or animal are called **communicable diseases** or **infectious diseases**. - Communicable diseases are carried from person to person in a number of ways. - The main sources of infection are: - **Through direct contact with a sick person**, as in the case of ringworm and chickenpox. - **Through air**, also known as droplet infection, as in the common cold and flu. When a sick person sneezes or coughs, microbes are released into the air. These can infect a healthy person breathing the air. - **Through contaminated food and water**, as in cholera and typhoid. - **Through insects** such as flies, fleas and mosquitoes, which are carriers of microbes. - When a mosquito bites an infected human, it carries microbes with it and transfers them to any healthy person it bites afterwards. - Diseases such as malaria, dengue fever and yellow fever spread in this way. - Fleas transfer the bacterium that causes bubonic plague from rats to humans. - Flies carry microbes from contaminated food to clean food. # Table 2.1 Diseases caused by microorganisms | Disease | Cause | Method of spread | Symptoms | Prevention | |-----------------|-----------------------------------------------|-------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------| | Cholera | Bacterium: *Vibrio cholerae* | Contaminated water or food | Severe diarrhoea, dehydration, vomiting, abdominal pains | Vaccination | | Tuberculosis (TB) | Bacterium: *Mycobacterium tuberculosis* | Droplet infection | Persistent cough, fever, fatigue, weight loss, blood in sputum | BCG vaccination | | Typhoid | Bacterium: *Salmonella typhi* | Contaminated water or food | High fever, acute headache, constipation, dry cough | Anti-typhoid inoculation | | Gastroenteritis | Many viruses and bacteria | Mainly food-borne | Diarrhoea and vomiting within hours of eating an infected meal | No vaccine; antibiotics can be taken for bacterial infections | | Common cold | Many viruses | Droplet infection | Fever, headache, runny nose, sneezing and coughing | No vaccine; avoid crowded places; cover nose and mouth when coughing and sneezing | | Poliomyelitis (polio) | Polio virus | Through human faeces | Fever, headache, destruction of nerve cells causing stiffness, paralysis and muscle wastage | Polio vaccine by mouth and injection | | Malaria | Protozoa: *Plasmodium* species | Through infected mosquitoes | Recurring chills and fever | Check breeding of mosquitoes | | Ringworm | Fungus | Transmitted to humans from pets or livestock, or from infected bedding | Itchy ring-shaped patches | Maintain hygiene; infection can be treated with antifungal medication | # Diseases caused by microorganisms - **Through animal bites**, as in the case of rabies. The bite of an infected dog can spread the disease to a human. - **Through cuts and wounds**, as in the case of tetanus. - Different pathogens act in different ways. - Some produce **toxins**, while others invade cells or tissues, and then produce toxins. - The symptoms of the disease appear only after a brief lapse of time, during which the microbes multiply rapidly. - The period between the infection and the appearance of symptoms is called the **incubation period**. - The symptoms may be fever, headache, nausea, vomiting, rashes and so on. - **Viruses cause diseases** such as the common cold, measles and influenza. These diseases spread through the air. - **Fungi and bacteria grow on food**, releasing toxic substances and spoiling the food. This leads to food poisoning. - **Bacteria cause pneumonia, tetanus, tuberculosis and cholera.** - **Protozoa cause malaria and amoebic dysentery.** - **Microorganisms also cause diseases in plants and animals.** - **Leaf mosaic viruses enter and damage the outer cells of leaves.** - **Potato blight in potato plants is caused by a fungus.** - **Mildew in grapes, roses, gooseberries and other flowering plants is caused by fungi.** - **Rust in wheat and other cereals is caused by fungi.** - **Foot-and-mouth disease in cattle is caused by a virus.** # Food Preservation - Have you ever felt ill soon after eating a meal? If so, you may have eaten spoilt food. - Food has to be kept free of the growth of moulds and bacteria, which spoil food and cause food poisoning and other diseases. - Many fungi and bacteria are decomposers. - They are responsible for the decomposition of dead organic matter. - When fungi and bacteria come in contact with food, they begin to decompose the food and release **chemical toxins**. - These contaminate or spoil food, making it unfit to be eaten. - When food is stored for use at a later date, it is important to prevent it from getting damaged by the activities of: - microbes-bacteria and fungi - insects-flies, weevils and so on - rodents-mice, rats and so on - natural chemical changes which take place within food - To prevent spoilage of food by insects and rodents, food should be kept covered or in closed containers. - However, it is not always possible to keep food away from microbes. - It is, therefore, much better to kill the microbes or make sure that the conditions are not suitable for their growth. - This will prevent food-borne diseases and keep food fit to be eaten for a longer period. - Processing of food to prevent its spoilage and to retain its nutritive value for long periods is called **food preservation**. - Food preservation helps us in many ways. - It reduces wastage of food. - It increases the storage period. - It enables food to be transported to distant places. - It helps to store food for use in seasons when it is not available. # Methods of Food Preservation - Food is preserved using many methods. - **Canning** Food and drink can be preserved by putting them in sealed, airtight containers. ## Food Preservation Methods - **Pasteurisation** Most bacteria in milk and other liquids can be killed by heating them to high temperatures and quickly cooling them down. This method ensures that the flavour of the food is not affected. - **Sun drying** Microbes cannot grow in dry conditions. So, water is removed from some vegetables like cauliflowers and fruits like mangoes by drying them in sunlight. - **Salting** Fruits and vegetables can be preserved by adding salt and then drying them. Salt prevents the growth of microbes. - **Pickling** Raw mangoes, gooseberries, lemons, and vegetables like cauliflowers, onions and cucumbers are preserved in vinegar or brine (salty water) to prevent the growth of microbes and give them a sharp or spicy flavour. They are then eaten with other foods - **Adding sugar** Fruits are preserved in the form of jams and jellies by adding sugar. Sugar removes water from cells, preventing the growth of microbes. - **Refrigeration** Freezing stops the growth and multiplication of microbes but does not kill them. Frozen food should not be left in the open for long as the microbes will start multiplying again. # Assess Yourself Mark if you have understood the concept. - Microorganisms or microbes are tiny organisms that can only be seen under a microscope. - The five major groups of microorganisms are bacteria, viruses, protozoa, fungi and algae. - The ideal conditions for most types of microorganisms to survive well are enough oxygen, moisture, moderate temperatures of about 25-38 °C, darkness and suitable food supply. - The main uses of bacteria are: increasing soil fertility, cleaning the environment, in the food, leather and fibre industry, and in making medicines (antibiotics and vaccines). - Nitrogen gas can be fixed by bacteria in the root nodules of legumes. Denitrifying bacteria free nitrogen from the nitrates. - The process of circulation of nitrogen between the atmosphere, soil, plants and animals is called the nitrogen cycle. - Harmful microorganisms are called pathogens. They cause communicable diseases such as cholera, polio, flu, dysentery and hepatitis. They also cause diseases in plants and animals. - Communicable diseases spread through direct contact, air, contaminated food and water, insects, animal bites, and through cuts and wounds. - Pathogens cause diseases by damaging tissues or by producing toxins. - Food has to be preserved for later use and should be kept fresh. If microbes grow on it, the food gets spoilt and eating it may cause food poisoning. - Microbial activity in food is controlled by treating the food in a process called food preservation. Some methods of food preservation are canning, sun drying, salting, pickling, adding sugar and refrigeration. For self assessment.