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Classification of bacteria
1. Shape
2. Arrangement
3. Ability to accept gram stain
4. Habitat
5. Metabolism
6. O2 requirement
7. Beneficial/ harmful
Cont…
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4. According to the habitat
1. Thermophiles: 45 and 122 °C
Thermophilus aquaticus
2. Extreme thermophiles
3. Psychrophiles: -15 -100C
4. Psychrotrophs
5. Mesophiles - 20 - 450C
6. Hallophiles - High salt - Methanogens
Temperature requirement
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Autotrophic photosynthetic
Cyanobacteria (Blue-green algae) - Nostoc and Anaebena
Heterotrophic
Curdling milk
Production of antibiotics
Nitrogen fixation
Pathogens
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Industrial Application of bacteria
1. Nitrogen fixation
2. Bioremediation (Effective micro organisms)
3. Biological control
4. Growth promotion of plants
5. Usage in Genetic engineering and Biotechnology
6. Vaccine production
7. Antibiotic production
8. Fermentation
9. Usage in Dairy industry
10.Usage in Feed formulation industry
11.Usage in Fiber industry
12.Usage against environmental pollution
Cont….
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Bacterial insecticides
• Bacillus thuringiensis
• Bacillus sphericus
• Bacillus lentimobus • Bacillus popillae
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Cry Protein
Midgut pHProtoxins
Proteolytic processingProteolytic processing
Active toxins
Mode of action of Bacillus thuringiensis
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Tobacco curing
Crude dry tobacco leaves pass through curing and ripening processes before they are ready for use
Bacteria are employed in both these processes and the peculiar taste and smell in the tobacco is due to the bacterial activity
For this purpose molasses and alcohol are added to tobacco.
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Ammonifying bacteria
Bacillus subtilisBacillus mycoidesBacillus ramosus
Act upon the dead animal and plant tissues
Decompose their complex organic compounds like proteins into ammonium compounds (Humus)
They are also known as putrefying bacteria
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Found in the soil
Fixes the nitrogen gas of the atmosphere in the presence of carbohydrates
This fixation of free nitrogen from the atmosphere through ammonia into free nitrates and again their conversion into ammonia and free nitrogen takes place by means of nitrifying and denitrifying bacteria, along with other organisms
Azotobacter
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Vinegar making industry
Bacillus aceti convert the sugar solution into
vinegarAlcohol and acetone manufactureButyl alcohol and acetone are manufactured by the action of bacteria on molasses
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Tea curingCrude tea leaves are acted upon by certain bacteria. The process is known as curing, which is employed to impart a peculiar taste and flavour to the leaves. For this purpose alcohol is added to tea leaves.
Leather tanningThe hides and skins after drying, salting and clearing are steeped in fluids containing specific bacteria. The process of fermentation goes on for some time and then they are transferred to tan-pits and are further allowed to be fermented. This whole process is known as tanning and the bacteria employed in the process are obtained from cowdung and the excreta of dogs and poultry.
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Fibre rettingRetting is the process of separating fibres from-the plant tissues. Bacteria are employed in this industry, which cause decay of the softer tissues and render fibres easily separable mechanically. Fibres of flax, hemp, jute, coconut and other fibrous plants are obtained by immersing the specific plant organs in stagnant pond water where bacteria develop and cause retting.
The sewage workIn order to remove solid and semi-solid constituents of sewage it is allowed to putrify. Putrifying bacteria are allowed to act upon sewage under anaerobic conditions. It gets decayed and liquefied. It is now filtered and the liquid is either drained out to the river or used as manure in fields. For this purpose, in the soak pits the horse dung is filled up.
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EnsilageIt is the process of preserving green fodder in pits. Certain bacteria help in the preservation of fodder.
MedicinesAntitoxins are the chemical substances produced in the host tissues in response to the attack of parasitic bacteria. Different vaccines and serums now prepared from these antitoxins are used in the treatment of specific ailments. The antibiotics such as streptomycin, aureomycin and chloromycetin are obtained from certain actinomycetous bacteria.