Q.5. Write note on food poisoning (2006)
Ans. Food Poisoning :- All activities of bacteria are not beneficial. Some saprophytic bacteria cause decay of our food and make it unpalatable. The activities of certain bacteria produce powerful toxins are powerful enough to cause food poisoning which results in serious illness and even death. Some species of staphylococcus are the common offenders. There is another dangerous food poisoning bacterium known as clostridium botulinium. It causes botulism - a fatal form of food poisoning.
Clostridium botulinum exists as spores in the intestines of many fish, birds and baryard animals as cows and horses and also in human intestines. The spores reach the soil in manure, sewage and organic fertilizers and may be attached to harvest foods.
This is the second most common food- borne disease caused by Clostridium perfringeus. The symptoms are due to a toxin that increases the water secretion in the latter part of small intestine, leading to diarrhea. There are abdominal pairs but no fever or blood involvement. The toxins may be produced under anaerobic conditions in canned foods as well as the intestine. Death is rare, and severe cases treated with antitoxin and penicillins.
Q.6. Write inbrief the economic importance of bacteria. (2007, 09, 12)
Related Questions -
Q. Write short note on Role of bactria in Agriculture. (2012)
Q. What is the role of bacteria in our life? ( 1997, 99)
Q. Describe in detail the useful and harmful activities of Bacteria. (2005)
Q. Write short note on Economic importance of bacteria. (2013)
Ans. The economic importance of bacteria derives from the fact that bacteria are exploited by humans in a number of beneficial ways. Despite the fact that some bacteria play harmful roles, such as causing disease and spoiling food, the economic importance of bacteria includes both their useful and harmful aspects.
Useful Bactria: -
(A) In Agriculture-
(i) In Soil Fertility :-
Some bacteria increase the fertility of soil. N2 is essential for all plants and about 80% N2 is present in atmosphere. All plants take N2 in the form of nitrates. These bacteria which fix the N2 belong to two categories.
(a) Nitrogen Fixing Bacteria:-
Some bacteria live free in soil as azobacter and Clostridium. These live in root nodules of leguminous plants. Rhizoibium leguminosorum. These bacteria converts the atmospheric N2 into Nitrogen compounds. This process of N2 transformation is called N2 fixation.
(b) Nitrifying Bacteria:-
These bacteria convert free N2 into ammonium compounds. These ammonium compounds are converted into nitrates by Nitrosomonas and nitrites are converted into nitrates by Nitrobacter.
(ii) Decomposition of Plants and Animals:-
Some bacteria bring about the decomposition of proteins, fats, carbohydrates and complex organic compound of the bodies of plants and animals.
(B) In Industry:-
(i) In Dairies products:-
Formation of curd, butter, ghee and cheese etc. are brought about by lactic acid bacteria.
(ii) Manufacture of venegar production:-
Sugar solutions are commercially fermented by Mycoderma aceti into acetic acid used as venegar.
(iii) Manufacture of acetone and alcohol:-
Both acetone and alcohol are commercially produced by sugary solution of molasses using anaerobic bacteria Clostridium.
(iv) ‘Curing’ and ‘ripening’ of tea and tabacco: -
Bacteria are used for ‘curling’ crude leaves of tea and tabacco. After harvesting, crude leaves are hung in shade and are permitted for certain bacterial (Mycrococcus candisans) action. The process adds flavour and tastes to tea and tabacco leaves increasing their market value.
(v) Bacteria used for fibre xetting:-
The intact fibres of jute, hemp, flax etc. are separated by baterial action. When these plants are immersed in water, they absorb water and swell and permit action of bacteria such as Clostridium butyclicum. Bacteria hydrolyse the pectic substances of the middle lamella. The fibres are thus separated and used in making of ropes and sacks.
(vi) Bacteria used in leather tanning industry:-
In certain cases, bacteria are used to tann the removed skin of animals into leather. It involves fermention which loosen the skin and assists in thes removal of skin hair. Though, this practice has been recently replaced by chemicals in modern days.
(c) Medicinal uses of Bacteria:-
(i) Vitamins: - Some species of Clostridium are used in the manufacture of Riboflavin ( a kind of vit. B ), e.g. C. butylicum is used to produce vitamin by fermentation of carbohydrate. Vitamins are valuable and are great asset to human body.
(ii) Antibiotics: - Antibiotics like thyrothrycin and subtilin are produced by bacteria like Bacillus brevis and B. sutilis, respectively. The subtilin is used as powerful food preserver.
Harmful Bacteria:-
1. Human Diseases: - Bacteria cause many serious diseases of man, e.g. tuberculosis, pneumonia typhoid, cholera, diphtheria, dysentry etc.
2. Animal Disease: -Tuberculosis of cattle, anthrax of sheep, chicken, cholera, pneumonia in horses, sheep and goats are various serious diseases caused by bacteria.
3. Plant Diseases: -Blight of peas citrus cancker, cotton rot, potato blank beg. soft rot of carrot cabbage of pine apple root and wilt disease of tomatoes potatoes, etc. are serious plant diseases caused by bacteria.
4. Bacteria cause food spoilage:-
Bacteria along with certain fungi spoil the food stuffs (meat, fish, butter, vegetables, fruits etc.). In certain cases bacterial contaminated food causes, poisoning to man. Clostridium botulinum secrets poisonous toxins ands causes death. This phenomenon is called botulism.
5. Bacteria responsible for cottom deterioration:-
Cotton and its manufactured articles are commonly destroyed by Spirochaete cytophoga.
6. Bacteria cause penicillin destruction:-
Certain bacteria spoil it by secreting enzyme penicillase.
7. Bacteria reduce soil fertility:-
By denitrification process, bacteria break down nitrates present in the soil, thus liberating N2 in the atmosphere and reducing the soil fertility. Such bacteria are called denitrifying.
Q.7. For what Lederberg and Tatum are known? Explain in brief their major contribution. (2009)
Ans. Joshua Lederberg (May 23, 1925 - February 2, 2008) was an American molecular biologist known for his work in genetics, artificial intelligence and space exploration. He won the Nobel Prize in 1958 in Physiology or Medicine for discovering that bacteria can mate and exchange genes. He shared the prize with E. L. Tatum and G. Beadle who won for their work with genetics. In addition to his contributions to biology, Lederberg did extensive research in aritificial intelligence. This included work in the NASA experimental programs seeking life on Mars and the chemistry expert system Dendral.
Lederberg received his undergraduate degree in 1944. He began medical studies at Columbia’s college of Physicians and Surgeon while continuing to perform experiments. Inspired by Oswald Avery’s discovery of the importance of DNA, .Lederberg began to investigate his hypothesis that, contrary to prevailing opinion, bacteria did not simply pass down exact copies of genetic information, making all cells in a lineage essentially clones. After making little progress at Columbia, he wrote to E. Taturn Ryan’s post-doctoral mentor, a collaboration. 1946 and 1947, Lederberg took a leave of absence to study under the mentorship of Tatum at Yale University . They showed that the bacterium E coli entered a sexual phase during which it could share genetic information through bacterial conjugation.
Lederberg also showed in 1952 that bacteriophages could transfer genetic information between bacteria in Salmonella. In 1957, J. Lederberg founded the Department of Medical genetics at the University of Wisconsin - Madison. Throughout his carrier, Lederberg was active as a scientific advisor to the U. S. Government. Starting in 1950, he has been a member of various panels of the Presidential Science Advisory committee. In 1979, he became a member of the U.S. Defense Science, Board and the Chairman of President Jimmy Carter’s President’s Cancer Panel. In 1989, he received National Medal of Science for his contributions to the scientific world. In 1994, he headed the Department of Defense’s Task Force on Persian Gulf War Health Effects, which investigated Gulf War Syndrome. In 2006, Lederberg was awarded the Presidential Medal of Freedom.
Edward Laurie Tatum was born on December 14th, 1909, at Boulder, Colorado, U.S.A. He was educated at the University of Chicago and Wisconsin, taking his A. B. degree in Chemistry in 1931, his M. S. degree in Microbiology in 1932 and his Ph.D. degree in Biochemistry in 1934.
After taking his doctorate degree, he studied for a year at the university of Wisconsin and then was awarded a General Education Fellowship at the University of Utrecht, Holland. He then joined the Department of Biological Sciences at Stanford University, California, where he was Research Associate from 1937 until 1941 and Assistant Professor of Botany and Professor of Microbiology at Yale University. In 1948 he returned to Stanford University as Professor of Biology and letter became Professor of Biochemistry.
Tatum’S research has been concerned primarily with the biochemistry, nutrition and genetics of microorganisms and of the fruit fly, Drosophila melanogaster. During his fruitful collaboration with G. W. Beadle he took charge of the chemical aspects. of their joint work on the genetics of eye - colour in Drosophila and to work instead with the fungus Neurospora crassa, it was Tatum who discovered that biotin was necessary for the successful cultivation of this fungus on simple inorganic media and thus provided these two workers with the genetic material that they needed for the work which gained then, together with J. Lederberg, the Nobel Prize.
In 1953 he received the Remsen Award of the American Chemical Society. He is a member of the Advisory Committee of the national foundation and has served on research advisory panels of the American Committee of the national foundation and has’ served on research advisory panels of the American committee of the Nation Research Council on Grwoth. He also served for 10 years on .the Editorial Board of the Journal of Biological Chemistry. He is now a member of the Editorial Board of Science and of Biochimica et Biophysica Acta.