Bacteria is one of the first organisms to appear in Earth. These have different shapes, sizes and functions. These organisms lack nucleus, that is they are also called prokaryotes. These were discovered by Anton Van Leeuwenhoek by his self made microscope. These bacteria are found in every places of Earth, even on our skin. Most of these bacteria are useful and rest are pathogens.
Discovery of Bacterium
Although bacteria originated on earth about 4 billion years ago, these were discovered only in 1675 by Anton Van Leeuwenhoek by his self designed microscope. He observed these rod shaped ( other shapes of these bacteria were discovered later ) bacteria and their movement and called them tiny animalcules as they behaved like animals.
Study of Bacteria
Study of bacteria is bacteriology. It is important for making food products, in agriculture, e.t.c. It involves behavior, classification, functions, uses, pathogenic reactions and its characteristics. A person in the field of Bacteriology is a Bacteriologist.
Structure of Bacterium
The cells of bacteria are surrounded by a plasma or cell membrane. This membrane holds the cytoplasm and other proteins. These cells of bacteria lack nucleus, mitochondria, Golgi System and other common organelles found in animal and plant cells. So, these bacteria are called prokaryotes.
Reproduction
Bacteria reproduce by a process called binary fission having two process, mitosis and meiosis. This is an asexual reproduction. In mitosis, two identical diploid cells are produced from one diploid where as in meiosis, four different haploid cells are produced from one diploid. To study the growth of bacteria, a cultural medium like PDA ( potato dextrose agar ) or yeast extract is used. These bacteria are kept in agar plates and placed inside an incubator having room temperature (27 C). After one or two days, we can see the growth and study the process how it reproduces.
Pathogenic Bacteria
Pathogenic bacteria are disease causing bacteria. Some diseases caused by bacteria are tetanus, typhoid fever, diphtheria, syphilis, dysentery, cholera, tuberculosis and various other diseases.
Some pathogenic bacteria are Clostridium botulinum, Clostridium tetani, Streptococcus, Staphylococcus, Bacillus anthracis, e.t.c These bacteria not only cause diseases to humans, but also to animals and plants. Anthrax is a disease caused by Bacillus to animals. Leaf spot is a disease caused to plants by Pseudomonas. All these bacteria are very less when compared to useful bacteria.
Useful Bacteria
Pseudomonas
Many bacteria are useful. These are used in the production of curd where Lactobacillus converts the sugar into lactose. Acetobacter is used in vinegar production as it produces acetic acid. Bacteria is used to produce antibiotics also. Rhizobium is a bacteria used in farms as it converts atmospheric nitrogen into nitrites and nitrates. Various bacteria like Bacillus, Pseudomonas, nitrobacter are responsible for nitrogen cycle. These are used in various industries also. From this, we see that useful bacteria are more than pathogenic bacteria.
Latest Discoveries
The latest discovered Burrowing Bacteria burrows into plant roots and delivers nitrogen. This is a very useful bacteria and this can be used instead of fertilizers.
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Now, see the following video how a bacteria in saliva is seen through microscope:
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Article by- M. Santosh
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