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Introduction to Bacteria

Bacteria! Bacteria! Bacteria!... This is being heard anywhere and everywhere in our daily busy life. Even kids are familiarized with the word “Bacteria” through the visual media. Knowingly or unknowingly most of us are behind those products that claim to keep the bacteria away. But are all of them really harmful as it is being projected?? The answer is a big NO! Because the curd that we include in our diet is being produced by a bacterium named Lactobacillus. There are even many bacterial preparations that we take inside to maintain a healthy stomach. Not only that, a lot of useful bacteria are residing in our mouth, food tract, stomach, etc., but on the contrary, there are a lot of microbes that are capable of causing deadly diseases including food poisoning.
Bacteria are minute organisms that cannot be visualized by the naked eye. It is made up of a single cell. Their study requires an instrument known as the microscope. It magnifies the size of the bacteria. A structure called cell wall accounts for the shape of the bacterial cell. Some bacteria have the ability to move, with the help of structures called flagella, pili, fimbrae, etc., but some bacteria are non-motile. Bacteria grow by a process called binary fission, where the single bacterial cell divides to form two daughter cells.
For growth and multiplication, the minimum nutritional requirements are water, carbon, nitrogen and inorganic salts. Bacteria normally grow on humans and animals and also on other natural sources. Under laboratory conditions, they are grown on artificial nutrient culture media.
Naming of bacteria is usually done in two ways. One is the common name which is in the local language, which helps in easy communication. The second is the scientific name which is the same throughout the world.
Bacteria are of different kinds, those that are useful and those that cause infections. Bacteria that cause infection are called pathogens. The lodgment of bacteria on a tissue of a host constitutes infections.
Sources of infection include human beings, soil, water, food, animals, insects, etc. Methods of transmission of infection are direct contact, inhalation, ingestion of food or drink that carries a pathogen, from mother to baby during birth, from hospitals, etc.
Some bacteria cause diseases by producing toxins, which are of two types- exotoxin and endotoxin. Exotoxins are heat labile proteins secreted by bacteria, containing poisonous substances. Whereas, endotoxins are heat stable and are active only in large doses.
Infectious diseases may be localized or generalized. Localized infections may be superficial or deep seated. Generalized infections spread throughout the body through the bloodstream resulting in bacteremia. Circulation of bacteria in the blood is called bacteremia.
Examples of bacteria causing infections are wound infections, abscess. It is caused by bacteria named Staphylococcus.
Even though bacteria cause diseases, they help to break down dead organic matter and they make up the base of the food web in many environments. Bacteria are of such immense importance because of their extreme flexibility, capacity for rapid growth and reproduction, and great age - the oldest fossils known, nearly 3.5 billion years old, are fossils of bacteria-like organisms.



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