Economic Importance of Bacteria

Most bacteria are heterotrophic i.e. they depend on ready-made food from different sources. In this category, the bacteria maybe:

1. Saprophytic — Such bacteria draw nourishment from decaying dead organisms.
2. Parasitic — Such bacteria draw nourishment from the body of their living hosts.

The bacteria secrete powerful enzymes from their cells into the surrounding food containing material. The enzymes make the food material soluble which is then absorbed as a solution into the bacterial cell.

Uses of bacteria in industry:

1. Tanning of leather — It is brought about by sunlight with the involvement of a few bacteria which breakdown the soft perishable parts of the skin.
2. Tea curing — Different flavours of tea are produced by certain bacteria.

Antibiotics are chemical substances produced by a living organism which inhibits or kills the growth of micro-organisms that cause the diseases such as fungi and bacteria. Examples of antibiotics are:

1. Streptomycin
2. Penicillin

A special category of soil bacteria (Rhizobium) is found living in small nodules on the roots of leguminous plants. These bacteria pick up free nitrogen from the soil and atmosphere and convert it into soluble nitrates. These nitrates are used by the host plant and also by other plants sown later in the same soil.

Denitrifying bacteria in the soil break down nitrates present in the soil to release nitrogen gas which enters the atmosphere. Pseudomonas is an example of denitrifying bacteria.

These are unicellular and prokaryotic.

Reason — Bacteria are single-celled organisms that lack a nucleus and membrane-bound organelles. Unlike plants, which are multicellular and have eukaryotic cells, bacteria are classified as prokaryotes. This fundamental difference in cellular structure and organization led to their separation from the plant kingdom.

Streptomyces

Reason — Streptomycin was discovered next to penicillin by Selman Waksman. It was derived from Streptomyces griseus.

Bacillus

Reason — Rod-shaped bacteria are called bacillus.

Rhizobium

Reason — Rhizobium is the nitrogen fixing bacteria present in root nodules of legumes.

Peptidoglycan

Reason — The bacterial cell wall is made up of Peptidoglycan and not cellulose as in plants.

Plasmid

Reason — Plasmid is a small circular DNA suspended in the Cytoplasm.

Binary fission

Reason — Bacteria divides into two by simple cell division. This is known as binary fission.

They do not have a well defined nucleus enclosed in a nuclear membrane.

Reason — The cells in which the nuclear membrane is absent is called prokaryotes.

Typhoid

Reason — TAB is the vaccine of Typhoid. It contains killed typhoid bacteria.

Vaccines

Reason — Vaccine consists of weakened or dead germ substances. Administration of vaccine results in resistance in body against the particular disease.

1. Cocci (spherical bacteria)
2. Bacilli (rod-shaped bacteria)
3. Spirilla (twisted or spiral bacteria)
4. Vibrio (comma-shaped)

1. Diplococci
2. Streptococci
3. Staphylococci

Bacteria mostly shows saprotrophic and parasitic nutrition.

The common method of reproduction in bacteria is fission or cell division.

Bacteria produce spores to overcome unfavourable conditions.

In air, bacteria can be present in the form of spores.

Spore formation in bacteria cannot be considered as a form of reproduction as they can reproduce through asexual means only such as cell division or fission. The formation of spores in bacteria is only an escape tactic from unfavorable condition that is exhibited by them.

Bacteria are unicellular organisms that lack membrane bound cell organelles like chloroplast, mitochondria, etc. and even a well-defined nucleus is absent which states that they have a simpler cellular organization.

(a) Antibiotics — An antibiotic is a chemical substance produced by a living microorganism which can stop the growth of or kill some disease-producing bacteria and fungi.

(b) Antitoxins — Antitoxin is a substance produced in animal bodies which reacts with the poison (toxin) produced by the invading germs.

(c) Serum — Serum actually means blood plasma from which fibrinogen has been removed. It may contain numerous chemical substances including anti-bodies and antitoxins.

(d) Botulism — Botulism is a very serious food poisoning due to a special bacterium sometimes found in tinned or sealed foods.

(e) Pasteurization — Pasteurization is the process of food preservation, applied usually to milk. In this process, the milk is heated at 60°C for 30 minutes and then chilled quickly. It kills majority of bacteria.

(a) Anthrax and Bovine tuberculosis

(b) Bacterial blight of cowpea and Black rot of mustard

(c) Cholera and Tuberculosis

(d) Nitrosomonas and Nitrobacter

(e) Azotobacter and Clostridium

(a) TAB — Typhoid-paratyphoid A and B

(b) BCG — Bacille Calmette-Guerin

(c) DNA — Deoxyribonucleic Acid

(d) GMO — Genetically Modified Organism

(a) Direct sunlight contains ultraviolet radiations of the Sun, which help in killing of mould spores present in air. Hence, it is advised that every living room in the house should get direct sunlight at least for a short time.

(b) No, tinned and sealed food are not always safe to eat as it may contain harmful bacteria like Clostridium botulinum that causes food poisoning. Clostridium botulinum releases toxins under low-oxygen conditions. These toxins are very lethal and can block nerve functions leading to muscular and respiratory paralysis.
Moreover, the chemicals used in the inner coating of the container can be harmful for humans.

(a) Difference between Decay and Putrefaction:

(b) Difference between Pasteurization and Sterilization:

Yes, bacteria can exist in aquarium. Bacteria can exist practically everywhere, as they can withstand any climatic condition.

(a) Below diagram shows the Nitrogen cycle:

1. Nitrification — The conversion of atmospheric nitrogen to nitrates is called nitrification.
2. Denitrification — The conversion of nitrates into atmospheric nitrogen is called Denitrification.

(b) Difference between biological nitrogen fixation and industrial nitrogen fixation are:

(c) Symbiotic relationship.

(a) Fishes and snails are present in the aquarium shown here.

(b) Yes, aquariums contain bacteria. A balanced aquarium contains some nitrifying bacteria like Nitrosomonas and Nitrobacter which converts the ammoniacal waste released by fish to nitrates. The filter media and various solid surfaces in the aquarium, such as gravel, rocks, plants, and decorations, harbor these bacteria in abundance.

(a) Flagella

(b) Curing

(c) Leather tanning

(d) Black rot of mustard

(e) Selman Waksman

(a) The first antibiotic penicillin was discovered by Alexander Fleming.

(b) Rhizobium bacteria is found living in the nodules on the roots of leguminous plants.

(c) The hormone insulin was the first substance produced by Escherichia coli.

(d) Pseudomonas is an example of denitrifying bacteria.

(e) Saprotrophic and parasitic are the two heterotrophic modes of nutrition in bacteria.

(a) Nitrosomonas

(b) Nitrobacter