7. Introduction to Microbiology

 

Applied Microbiology :-

                                         The branch of biology which deals with the study of enzymes related to some prokaryotes and eukaryotic microbes, proteins, applied genetics, molecular biology etc. is called as applied microbiology.

 

 Industrial Microbiology :-

                             When microbiology is used for commercial purpose as well as economic, social and environment related processes, then it is called as industrial microbiology.

 

      Main features of industrial microbiology

 

1)    Using fermentation process, different products such as bread, cheese, wine and raw material for chemical reactions is produced.

2)   Use of microbes for garbage management and pollution control.

 

                              Products

A. Dairy products

               By preparing various milk products, one can preserve milk for a long time. Cheese, butter, kefir, yoghurt etc. are some important milk products.

                                     While making these products the water content and acidity of the milk is changed. Due to this, texture, taste, aroma and flavor is changed.

 

               Basic process on milk in dairy

1)    Milk is pasteurized at the start to destroy harmful microbes.

2)   Then the milk is fermented by using lactobacilli.

3)   In this process, lactose sugar present in the milk is converted into lactic acid.

4)   Due to lactic acid, the milk proteins get coagulated.

5)   Besides this, compounds with taste and flavor are formed like Diacetyl.

 

                           Production of Yoghurt

 

1)    Yoghurt is produced from the milk with the help of lactobacilli.

2)   The condensed milk powder is mixed with milk to increase the protein content of the milk.

3)   The milk is boiled and then it is cooled till it becomes lukewarm.

4)   Then the bacterial strain of Streptococcus thermophilus and Lactobacillus delbrueckii   

 are added to it in the proper proportion.

5)   The streptococcus bacterium converts the milk into solution containing lactic acid. This makes the protein to get out. It makes the yoghurt dense.

6)   The lactobacilli form aldehydes like compound which gives the characteristic taste to the yoghurt.

7)   Various fruit juices can be mixed with yoghurt to impart different flavours forming strawberry, banana, mango etc.

8)   The pasteurization is carried out to increase the self life of yoghurt and improve its probiotic properties.

 

Butter:

Butter is of two types namely sweet cream and cultured. For large scale production of cultured butter microbes are used.

 

Cheese production:-

1)    Cheese is made from cow’s  milk. Chemical and microbiological testing of milk is done.

2)   Three types of  bacteria i.e. Lactobacillus lactis, Lactobacillus cremoris and Streptococcus thermophilus along with some color is added to the milk.

3)   It imparts sourness to the milk and it is converted into yoghurt like substance.

4)   The water from this yoghurt is removed to make the yoghurt denser.

5)   The enzyme protease is added to the mixture to make it denser.

6)   Later, cutting the solid yoghurt into pieces , washing, rubbing, salting and mixing of essential microbes, pigments and flavours is done.

7)   The pressed cheese is then cut into pieces and sorted for ripening.

 

Probiotics:-

1)    Probiotic substances are mostly milk products containing live active bacteria.

2)   The useful colonies of bacteria are produced in the elementary canal of human being due to the probiotics.

3)   Probiotics decreases the population of harmful microbes like clostridium from our intestine.

4)   It enhances the immunity due to regular intake in the diet.

5)   Probiotics reduces the ill effects of harmful substances formed during metabolic activities.

6)   Due to intake of antibiotics useful microbes becomes inactive, but probiotics makes them active again.

7)   Now a days probiotics are used for treatment of diarrhea and treatment of poultry.

 

Bread:-

1)    Breads are produced from the flour of cereals.

2)   Dough is prepared by mixing together the baker’s yeast (Saccharomyces cerevisiae) , water, salt and other necessary materials with flour.

3)   Due to fermentation, sugar is converted into the carbon dioxide and ethanol.

4)   While baking the dough carbon dioxide is released and the bread becomes fluffy and spongy.

5)   Compressed yeast containing carbohydrates, proteins, vitamins and minerals is used in commercial bakery industry.

6)   Dry granular yeast is used for domestic use.

 

Vinegar production

1)  4 % acetic acid is called as vinegar.

2)   With the help of the S. cerevisae, ethanol is obtained by fermentation of fruit juices, maple syrup, sugar molasses, starch of the roots etc.

3)   Then for the microbial degradation of ethanol, a mixture of bacterial strains like Acetobacter and Glucanobacter is used. Ethanol is converted into acetic acid and other by-products are obtained.

4)   The acetic acid is separated from mixture by rarefaction.

5)   Potassium ferrocyanide is used to bleach this acetic acid.

6)   Finally the pasteurization is done followed by the mixing of small amount of SO₂ (Sulphur dioxide) gas to produce vinegar.

 

 Uses of vinegar

1)    Vinegar is used for the preservation of pickles, sauces, ketchups, chutneys etc.

2)   It imparts the sour taste to food materials.

 

Soya sauce:-

            Fungus Aspergillus oryzae is used to ferment the mixture of flour of wheat or rice and soyabean to produce soya sauce.

 

Microbial enzymes:-

                                     The enzymes obtained by the activity of microbes are used in the  industrial processes. These microbial enzymes are better than chemical catalysts.

Advantages of microbial enzymes

      1)    Microbial enzymes work at the low temperature, pressure and Ph

2)   Energy is saved in the processes using microbial enzymes.

3)   There is no need of erosion proof instruments for the processes.

4)   Unnecessary products are not formed in the process.

5)   Purification is not needed and hence expenses on purification are reduced.

6)   Enzymes can be reused.

7)   Microbial enzymes are eco-friendly because elimination and decomposition of waste material is avoided.

 

Use of microbial enzymes in industries:

1)    Microbial enzymes are used in detergents in cleaning process to remove dirt at low temperature.

2)   It is used to obtain glucose and fructose syrup from corn flour using enzymes of cacilli and streptomyces.

3)   They are used in various industries like cheese, paper, textile, leather, plant extracts etc.

 

Xanthan Gum:-

1)    Xanthan gum is obtained by fermentation of starch and molasses with help of Xanthomonas species.

2)   It is soluble in hot water and cold water so it is very useful.

3)   It is used in the production of pigments, fertilizers, toothpaste, weedicides, high quality paper etc.

4)   It is used to impart thickness to ice-cream, milkshakes, chocolates, instant soups etc.

Antibiotics:

                     Antibiotics are the medicines obtained from the bacteria and fungi by carrying out  certain processes.

                     Some human diseases and other animal diseases are controlled by using antibiotics.

Examples: Penicillin, cephalosporin, gentamycin, streptomycin, Tetracyclin, ampicillin, amoxicillin,

                monobacton, bacitracin etc.

  

Microbes and fuels:- 

1)    Methane is obtained from agricultural and industrial waste by microbial anaerobic decomposition.

2)   Ethanol is a clean fuel which is obtained during fermentation of molasses by yeast.

3)   Hydrogen is a fuel of future. It is released when bacteria perform bio-photolysis of water.

 

        Advantages of fuels obtained from microbes

1)  They are not polluting.

2)  The conventional fuels are exhaustible. After few hundred years, they will be exhausted. Fossil fuels cause lot of air pollution due to emission of carbon dioxide. So it is necessary to increase the use of such fuels.

 

                                Microbial pollution control:-

1)    With the help of suitable microbes, the environmental problems can be tackled.

2)    Microbes are used in biogas plants, compost production, sewage treatment etc.

Bio- fuel:

 

              Bio- fuel is a good and renewable source of energy. They are easily available and in abundance. They are called as reliable fuels of the future. They are available in the following three forms.

1)    Solid:- Coal, dung, crop residue, dung cakes etc.

2)   Liquid :- Vegatable oils, alcohol, bio-diesel etc.

3)   Gaseous :- Gobar gas, coal gas

 

Land filling sites:-

   1)    In the land- filling sites the degradable wastes are transferred. Such sites are    

          away from the residential area.

2)   Large pits are dug in open spaces. These pits are lined with plastic sheets. So the leaching of toxic and harmful materials are avoided to reduce soil pollution.

3)   Compressed waste is put in the pit and is covered with the layers of soil, sawdust, leafy waste etc.

4)   Specific biochemical substances are added for speedy decomposition.

5)   Bioreactors which are the mixtures of bacteria are mixed at some places.

6)   Soil microbes and other top layers decompose the waste.

7)   Soil slurry is used to seal the pits completely.

8)   After a certain period, best quality compost is formed. Such sites can decompose more and more biodegradable waste and can be used again and again.

Clean Technology :-

                             Microbes have natural ability of decomposing the manmade chemicals. Hydrocarbons and other chemicals are transformed with the help of these abilities.

 

        Cleaning the oil spills of rivers and oceans with help of microbes

 

1)    The oil spills take place in rivers or oceans due to several reasons.

2)   This crude oil is highly toxic to the flora and fauna of the river or ocean.

3)   Oil spills can be removed by using mechanical means but it is very difficult.

4)  The culture of microbes like Pseudomonas species and Alcanovorax borkumensis.

5)   They have the ability to destroy the pyridines and other chemicals present in the HC.

6)   They are released at the place of the oil spills to clear them.

7)   These bacteria are called as hydrocabonoclastic bacteria (HCB). They decompose the HC and bring about the reaction of carbon with oxygen.

8)     In this process CO2 & water is formed. In this way oil spills are cleaned.

 

          Conversion of soil polluted by acid rain into fertile land 

1)    Acidophillium spp. And Acidobacillus ferroxidens arethe bacteria which have the capacity to use sulphuric acid as their energy source.

2)   Since this sulphuric acid is present in the acid rain, the bacterium becomes the right choice to control the same.

3)   In this way, bacteria can control the soil pollution occurring due to acid rain, making the soil fertile again.

 

                            Decomposition of plastic bottles by using microbes

1)    Plastic bottles are formed from the chemical substances PET ( Polyethylene Terephthalate Polyster).

2)   It has been observed that species like Vibrio, Ideonella sakaiensis can decompose PET.

3)   Species of fungi like actinomycetes, streptomyces, nocardia, actinoplanes have the ability of decomposing rubber from garbage. 

 

                       Microbes and farming

 

 Microbial Inoculants:

1)  Microbes containing inoculants are produced by the process of fermentation.

2)  They are used for spraying on seeds before sowing.

3)  Some of them are released into the plants.

Examples: Solution containing Azotobacter, artificial nitrogenase.

 

Benefits of Microbial Inoculants:

1)  Microbial inoculants provides the nutrients to the growing plants.

2)  They increase the fertility of the soil.

3)  They improve the quality of vegetarian food.

4)  Harmful chemicals present in the soil are removed by using microbial inoculants.

 

Bioinsecticides:

1)    Through biotechnology, bacterial and fungal toxins are directly integrated into plants. These plants are protected against fungal and pest attack.

2)   Being toxic to insects, they do not consume these plants.

Example: Spinosad

 

Give reasons:

1)  Use of mutant strains has been increased in industrial microbiology.

1)    In industrial microbiology, the commercial use of microbes is done.

2)   In such experiments, various economic, social and environmental issues are handled.

3)   To find the more effective solutions and the products the mutant strains are used.

 

2)  Enzymes obtained by the microbial process are mixed with the detergents.

1)  When detergents are mixed with the microbial enzymes, they works efficiently.

2)  These enzymes works at low temperature.

3)  For better results, enzymes are mixed with detergents.

 

 

3)  Microbial enzymes are used instead of chemical catalysts in chemical industries.

1)    Microbial enzymes are active at low temperature, pressure and pH

2)   The energy is saved.

3)   The expenses on purification of the product are minimized.

4)   Unnecessary byproducts are not formed.

5)   Microbial enzymes are ecofriendly.

 

Answer the following questions

1)  How the bread does become spongy?

For the preparation of bread baker’s yeast is used in the dough. It is anaerobic organism. Anaerobic fermentation results in the formation of carbon dioxide and ethanol. When the dough is baked, the carbon dioxide gas escapes and bread becomes spongy.

 

2)   What are the benefits of mixing ethanol with petrol and diesel?

1)  Petrol and diesel are non-renewable sources of energy.

2)  When only petrol and diesel is used as fuel there is increase in pollution.

3)  When petrol and diesel is mixed ethanol, the proportion of pollutants which are emitted in the atmosphere becomes less.

4)  Due to the addition of ethanol, the price of fuel becomes less.

 

3)   Which plants are cultivated as fuel?

1)  Ethanol is obtained from the wheat, maize, beet, sugarcane and molasses of sugarcane.

2)  Biodiesel is obtained from the plants like jatropa, mahua, palm, jute, sunflower, mustard and some types of algae.