We have seen a lot of bad micro-organisms in previous chapters. However other than plants and animals, a lot of microbes form a major component of biological system on earth.
Micro-organisms like bacteria fungi and virus are present everywhere from soil to water and even inside our bodies. These can be found in ice cold environment as well as hot environments were temperature maybe as high as 100 degree Celsius.
Microbes in household products -
We use microbes in lot of daily to daily processes. For example milk is converted into curd by a bacteria called lactobacillus or lactic acid bacteria (LAB). Also bakers use fungus Saccharomyces cerevisiae to get soft bread. Hence this yeast is also called as bakers yeast.
Swiss cheese has large holes due to Carbon dioxide production by a bacteria known as Propionibacterium sharmanii. A very famous cheese called Roquefort cheese is right and by growing fungus Penicilliam roqueforti on it.
Microbes in industries -
Saccharomyces cerevisiae is also known as Brewer's yeast because it is used to produce alcohol. Drinks like whisky, brandy and rum are produced after distillation where as wine and beer are made without distillation process.
Penicillin is a very famous antibiotic discovered by Alexander Fleming while he was working on staphylococci bacteria. Penicillin is extracted from a fungus called Penicillium notatum.
A lot of chemicals and enzyme are also produced by microorganisms.
Acetic acid is produced by Acetobactor aceti which is a bacteria. Citric acid is produced by a fungi known Aspergillus niger. Butylic acid is produced by a bacteria Clostridium Butylicum. Lactic acid is produced by lactobacillus.
Cyclosporin A produced by Trichoderma polysporum fungi is used as immunosuppressive agent (useful for organ transplant patients).
Statins (Monascus purpureus yeast) – used as blood cholesterol lowering agents.
Microbes in sewage Treatment
Municipal waste water (sewage) contains large amount of organic matter and microbes which are pathogenic and cannot be discharged into natural water bodies like rivers and lakes.
Sewage is treated in sewage treatment plant to make it less polluting by using heterotrophic microbes naturally present in sewage. Sewage treatment is done in two stages-
In primary treatment, floating debris is removed by sequential filtration. Grit (soil and pebbles) are removed by sedimentation.
Secondary treatment or biological treatment involves passing of primary effluents in large aeration tank to help the growth of aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh like structures). These microbes increase the consumption of organic wastes and decrease the BOD (biochemical oxygen demand)of the effluents.
Sludge is passed into large tanks called anaerobic sludge digesters in which anaerobic bacteria digest the bacteria and fungi in the sludge and produce mixture of gas called biogas, which is a mixture of methane, hydrogen sulphide and carbon dioxide.
The effluents from the secondary treatment plant are released into water bodies.
Microbes in production of biogas
Biogas is a mixture of gases produced by the microbial activity that can be used as fuel.
Certain bacteria that grows anaerobically on cellulosic material produce large amount of methane along with CO2and H2. These bacteria are collectively called methanogens link methanobacterium.
Biogas Plant – the excreta of cattle (gobar) is rich in methanogens bacteria and is used for generation of biogas also called as gobar gas.
The technology of biogas production was developed in India mainly due to the efforts of Indian Agricultural Research Institute (IARI) and Khadi and Village Industries Commission(KVIC).
Microbes as Biocontrol Agents
Biocontrol means use of biochemical method for controlling plant disease and pests. The chemical used as pesticides and insecticides are harmful to human beings and animals.
Biological control of pests and disease is a method of controlling pest on natural prediction rather than chemicals. The organic farmer creates a system where the pests are not eradicated but kept at manageable level by complex system of check and balance within the living ecosystem. For example, the Ladybird and Dragonflies are used to get rid of aphids and mosquitoes respectively. On brassicas and fruit tree, to control butterfly Caterpillars, bacteria Bacillus thuringiensis is used.
Biological control developed for use in the treatment of plant disease is the fungus Trichoderma. Trichoderma are free-living fungi that are very common in the root systems that control several plant pathogens.
Baculoviruses are pathogens that attack insects and other arthropods. The majority of baculoviruses used as biological control agents are in the genus Nucleopolyhedrovirus.
Microbes as Biofertilizers -
The root nodule formed by Rhizobium bacteria on root of leguminous plants increase the nitrogen level of soil, necessary for various metabolic processes. Azotobacter and Azospirillum are free living bacteria that live in soil and fix atmospheric nitrogen into organic forms.
Symbiotic association of fungi with angiosperm plants (mycorrhiza) also increase the fertility of soil.
These microbes also provide benefits like resistance to root-borne pathogens, tolerance to salinity and drought.
Cyanobacteria (Nostoc, Anabaena, clostridium) an autotrophic microbes found in aquatic and terrestrial environment fix atmospheric nitrogen.
To download PDF - Click here to download Microbes in Human Welfare Mind Map PDF
To join telegram - Click here
0 Comments