Bacteria

Bacteria are microscopic and single-celled organisms. These exist in millions in all kinds of environments and not only inside but outside of other organisms also. One can find bacteria in soil, water, plants, animals and radioactive waste too. These exist in the earth’s crust, arctic glaciers as well as in the hot springs. Some kinds of bacteria are harmful, but many other kinds of bacteria are beneficial. Bacteria support different forms of life of plants as well as animals. These are also useful in industrial and medicinal processes. These are being considered the first organism which was appeared on earth.

For example, the oldest known fossils are bacteria-like organisms. Bacteria are using organic and some inorganic compounds in the form of their food. Different kinds of the gut microbiome or bacteria heavily affect human health.

Definition

Bacteria are those organisms which are having single cells only. These are neither plants nor animals. These are very minute organisms having the length of few micrometres and these exist together in communities of millions. For example, a gram of soil is typically containing about 40 million bacterial cells. Also, a millilitre of freshwater generally contains about one million bacterial cells. Our earth is estimated to hold at least 5 nonillion bacteria. They are very renowned due to their tremendous capacity to adapt and multiply in number. Their history is very old, nearly 3.5 billion years. Also, these are being recognized as the earliest fossils found on the earth. They can reproduce themselves by using the Binary fission procedure.

History

Approximately 2000 years ago Marcus Terentius suggested that diseases are being caused by tiny animals found in the air. He was the Roman author. Further, he advised people to avoid marshy places during the construction work. This was since those places might contain very tiny insects. And, such insects might enter the body through the mouth and nostrils and hence causing the diseases.

Later on, during the 17th century, a Dutch scientist, Antonie van Leeuwenhoek created a single-lens microscope. Through this, he saw animalcules, and further, those were termed as bacteria. Therefore, he is considered the first microbiologist. After many years, in the 19th century, chemists Louis Pasteur and Robert Koch discovered that germs are behind the diseases. At that time, it was known as the Germ Theory. Scientist Paul Ehrlich was the first scientist who had detected bacteria by using stains.

Types of Bacteria

In our environment, there are different types of bacteria.  We may classify them on the basis of various criteria. One such way for classification is on the basis of the shape of bacteria. Three basic classification shapes are Spherical, Rod and Spiral.

1. Spherical

Such bacteria have shapes like a ball or sphere. These are termed as Cocci as a group whereas a single bacterium is termed as Coccus. Streptococcus group is one such popular example that is responsible for throat infection. This nomenclature is obtained from the Greek term “Kokko,” which means berry. These types of bacteria are among the lowest and easiest bacteria having an average diameter of approximately 0.5 to 1.0 microns. Staphylococcus bacteria may trigger food poisoning and toxic shock syndrome. Another one is meningococcus, which is behind the epidemic bacterial meningitis.

2. Rod-shaped

These kinds of bacteria are known as bacilli in a group, whereas bacillus in particular. These are rod-shaped, and some of them are curved too. These are also termed vibrio. Bacillus anthracis (B Anthracis) is one such example of bacteria. These bacteria are having a more complex structure and nature in comparison to the class of coccus. These are 0.5 to 1.0 microns broad and 1to 4 microns long on average. One bacteria Yersinia pestis can trigger bubonic and pneumonic plague. On the other hand, some of these are beneficial bacteria and useful to create antibiotics. Also, some are good for the human intestinal tract helping for digestion.

3. Spiral

These kinds of bacteria are termed spirilla in group and spirillus in particular. The bacteria with very tight coils are spirochetes. Bacteria having a spiral shape cause Leptospirosis, syphilis etc. These bacteria appear almost worm-like with the observation under a microscope. Two very well-known such families are Treponema pallidum and Leptospira. Beneficial spirochetes are including the symbiotic spirochetes. They enter into the stomachs of ruminants like sheep, cattle, and goats. These are also residing in the termite’s intestines and hence are assisting in the wood and plant fibre digestion. Due to this, termites can remove rotted and diseased wood.

Structure of Bacteria

Bacteria are prokaryotes with single cells. These are lacking the nucleus but having thread-like mass which is termed as the nucleoid. Ribosomes are the spherical units present in the bacterial cell. Bacterial cells have two protective cells. External cell wall and the internal cell membrane. The bacterial cell is different in plants and animals.

Generally, a bacterial cell includes:

• Capsule: It is a layer non the outside of the cell wall.
• Cell wall: It is a layer of polymer material peptidoglycan, and found outside of the plasma membrane.
• Plasma membrane: It exists within the cell wall. It is permeable and may pass substances through itself.
• Cytoplasm: It is a gelatinous substance inside the plasma membrane. It contains genetic material and ribosomes.
• DNA: It contains all the genetic instructions of bacteria and it is located inside the cytoplasm.
• Ribosomes: Inside it, proteins are synthesized. These are complex particles made up of RNA-rich granules.
• Flagellum: It is required for the movement of bacteria. Also, some bacteria are having more than one flagellum.
• Pili: These are hair-like appendages on the outside of the cell. This helps bacteria to stick to surfaces. With Pilli, bacteria transfer genetic material to other cells. Therefore, it is responsible to spread illness in humans.

FAQs About Bacteria

Q.1: What is the role of bacteria in human survival?

Answer: There are many bacteria inside the human body. Hence they play an important role in human survival. For example, bacteria in the digestive system break down the nutrients for further easy processing. Also, non-hazardous bacteria help to prevent the diseases. Some bacteria attack pathogens to protect us from disease.

Q.2: What are the usages of bacteria in industries and researches?

Answer: Bacteria helps to break down the organic compounds. Therefore, it is useful for waste processing and cleaning up oil spills and toxic waste. Many pharmaceutical and chemical industries are using bacteria to produce certain chemicals. On the other hand, bacteria are useful in molecular biology, biochemistry and genetic research.

Q.3: What are some major hazards caused by Bacteria?

Answer: Some bacteria are the main cause of diseases in humans. Some of such diseases are cholera, diphtheria, dysentery, plague, pneumonia, tuberculosis, typhoid etc. With exposure to bacteria, the immune system of the human body attacks them for prevention.

Q.4: What are the different ways of feeding for bacteria?

Answer: Heterotrophic bacteria are getting their energy through consuming organic carbon. Most bacteria absorb dead organic material. Some parasitic bacteria also kill their host too. Whereas, autotrophs bacteria make their food by using photosynthesis or by using chemosynthesis. Bacteria using photosynthesis are photoautotrophs. On the other hand, the bacteria using chemosynthesis are chemoautotrophs.