MICROBES in human welfare Flashcards
making of curd from milk
Micro-organisms such as Lactobacillus and others
commonly called lactic acid bacteria (LAB) grow in milk and convert it to curd. During growth, the LAB produce acids that coagulate and partially digest the milk proteins. A small amount of curd added to the fresh milk as inoculum or starter contains millions of LAB, which at suitable temperatures multiply, thus converting milk to curd, which also improves its nutritional quality by increasing vitamin B12. In our stomach too, the LAB play a very beneficial role in checking disease-causing microbes
baker’s yeast
dough, which is used for making bread, is fermented using Saccharomyces cerevisiae
, the large holes in ‘Swiss cheese
are due to
production of a large amount of CO2 by a bacterium named Propionibacterium sharmanii.
‘Roquefort cheese
ripened by growing a specific fungi on them, which gives them a particular flavour.
antibiotics
Antibiotics are chemical
substances, which are produced by some microbes and can kill or retard
the growth of other (disease-causing) microbes
Penicillin
Alexander Fleming while working on Staphylococci
bacteria once observed a mould growing in one of his unwashed culture plates around which Staphylococci could not grow. He found out that it was due to a chemical produced by the mould and he named it Penicillin after the mould Penicillium notatum
antibiotics treated diseases like
plague, whooping cough , diphtheria and leprosy
microbes that produce organic acids
Aspergillus niger (a fungus) of citric acid, Acetobacter aceti (a bacterium) of acetic acid; Clostridium butylicum (a bacterium) of butyric acid and Lactobacillus (a bacterium) of lactic acid
ethanol
Yeast (Saccharomyces cerevisiae) is used for the commercial production of ethanol
lipases
used in detergent formulations and are helpful in removing oily stains from the laundry
bottled fruit juices bought
from the market are clearer as compared to those made at home. This is because the bottled juices are clarified by the use of
pectinases and
proteases.
. Streptokinase
produced by the bacterium Streptococcus and
modified by genetic engineering is used as a ‘clot buster’ for removing clots from the blood vessels of patients who have undergone myocardial infarction leading to heart attack
cyclosporin A
used as an immunosuppressive agent in organ-transplant patients is produced by
the fungus Trichoderma polysporum
Statins
produced by the yeast Monascus purpureus have been commercialised as blood-cholesterol lowering agents. It acts by competitively inhibiting the enzyme responsible
for synthesis of cholesterol
sewage
is treated in sewage treatment plants (STPs)
to make it less polluting.
Primary treatment
floating debris
is removed by sequential filtration. Then the
grit (soil and small pebbles) are removed by
sedimentation. All solids that settle form the
primary sludge, and the supernatant forms
the effluent
Secondary treatment
The primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into flocs,While growing, these microbes consume the major part of the organic matter in the effluent. This significantly reduces the BOD
BOD
BOD refers to
the amount of oxygen that would be consumed if all the organic matter in one litre of water were oxidised by bacteria
BOD test
The sewage water is treated till the BOD is reduced. The BOD test measures the rate of uptake of oxygen by micro-organisms in a sample of water
what happens after the bod of water is reduced
the effluent is then passed into a settling tank where the bacterial ‘flocs’ are allowed to sediment. This sediment is called activated sludge.
activated sludge
. A small part of the activated sludge is pumped back into the aeration tank to serve as the inoculum. The remaining major part of the sludge is pumped into large tanks called anaerobic sludge digesters
anaerobic sludge digesters
Here, other kinds of bacteria, which grow anaerobically, digest the bacteria and the fungi in the sludge. During this digestion, bacteria produce a mixture of gases
such as methane, hydrogen sulphide and carbon dioxide. These gases form biogas and can be used as a source of energy as it is inflammable
biogas
Biogas is a mixture of gases (containing predominantly methane) produced by microbial activity and which may be used as fuel.
methanogens
bacteria, which grow anaerobically on cellulosic material, produce a large amount of methane along with CO2 and H2, eg: Methanobacterium
where are methanogens found
These bacteria are commonly found in the anaerobic sludge during sewage treatment. These bacteria are also present in the rumen (a part of stomach) of cattle. A lot of cellulosic material present in the food of cattle is also present in the rumen. In the rumen, these bacteria help in the breakdown of cellulose and play an important role in the nutrition of cattle
goabr
the excreta (dung) of cattle, commonly called gobar, is rich in these bacteria. Dung can be used for the generation of biogas, commonly called gobar gas
biogas plants
The biogas plant consists of a concrete tank (10-15 feet deep) in which bio-wastes are collected and a slurry of dung is fed. A floating cover is placed over the slurry, which keeps on rising as the gas is produced in the tank due to the microbial activity. The biogas plant has an outlet, which is connected to a pipe to supply biogas to nearby houses. The spent slurry is removed through another outlet and may be used as fertiliser. Cattle dung is available in large quantities in rural areas where cattle are used for a variety of purposes. So biogas plants are more often built in rural areas
biocontrol
Biocontrol refers to the use of biological methods for controlling plant
diseases and pests. In modern society, these problems have been tackled increasingly by the use of chemicals – by use of insecticides and pesticides. These chemicals are toxic and extremely harmful, to human beings and
animals alike, and have been polluting our environment
the Ladybird,
and Dragonflies
e useful to get rid of aphids and mosquitoes,
respectively
Bacillus
thuringiensis
to control butterfly caterpillars
how bt works
. These are available in sachets as dried
spores which are mixed with water and sprayed onto vulnerable plants such as brassicas and fruit trees, where these are eaten by the insect larvae. In the gut of the larvae, the toxin is released and the larvae get
killed. The bacterial disease will kill the caterpillars, but leave other insects unharmed
Bt-cotton
Because of the development of methods of genetic engineering in the last decade or so, scientists have introduced B. thuringiensis toxin genes into plants. Such plants are resistant to attack by insect pests
A biological control being developed for use in the treatment of plant
disease is the
fungus Trichoderma. Trichoderma species are free-living fungi that are very common in root ecosystems. They are effective biocontrol agents of several plant pathogens
Baculoviruses
pathogens that attack insects and other arthropods. used as biological control agents are in the genus Nucleopolyhedrovirus. .no negative impacts on plants, mammals, birds, fish or even on non-target insects
bacteria as biofertilizers
the nodules on the roots of leguminous plants
formed by the symbiotic association of Rhizobium. These bacteria fix atmospheric nitrogen into organic forms, used by the plant as a nutrient. Other bacteria can fix atmospheric nitrogen while free-living in the soil (examples Azospirillum and Azotobacter), thus enriching the nitrogen content of the soil
fungi as biofertilizers
Fungi form symbiotic associations with plants (mycorrhiza), like Glomus fungi. absorbs phosphorus from soil and passes it to the plant. Plants having such associations show other benefits also, such as resistance to root-borne pathogens, tolerance to salinity and drought, increase in plant growth
