Biotechnology for Sustainable Agriculture - Ram Lakhan Singh, Sukanta Mondal
Pg. No. 29 - 33
Biofertilizers
In strict sense, biofertilizers are not fertilizers. They are directly used for supply of
nutrition to crop plants. Microorganisms such as bacteria, fungi, and blue green algae are
largely used as biofertilizers. These organisms are added to the rhizosphere of the plant to
enhance their activity in the soil. They help the plants indirectly through better nitrogen fixation
or improving the nutrient availability in the soil. Their mode of action differs and can be applied
alone or in combination. By systematic research, efficient cultures are identified which are able
to grow in given soil and climatic conditions. Such cultures are prepared at large scale in
laboratory and distributed to farmers. For sufficient shelf-life, they are packed in carrier
materials such as peat and lignite powder. Recently, use of biofertilizers is gaining momentum
due to the increasing importance of maintenance of soil health, reducing environmental
pollution, and the use of harmful chemicals in agriculture. For optimum plant growth, it
requires nutrients in sufficient and balanced amount, but from the soil, only small portion of
nutrients is released each year through biological and chemical processes. Therefore, fertilizers
are used to supplement the nutrients which are already present in the soil (Chen, 2006).
Microorganisms of biofertilizers play a vital role in accelerating the microbial processes such
as controlling soil-borne diseases, improving the soil health, and soil properties. Biofertilizers
can provide an economically viable option to small farmers for realizing the ultimate goal of
increasing crop productivity. These are low-cost, effective and renewable sources of plant
nutrients to supplement chemical fertilizers.
Biopesticides
Biotechnological tools provide solutions to common basic and applied problems that
hinder use of insects’ natural enemies as biological control agents. Commercially, biopesticides
include microorganisms that control pests (microbial pesticides), naturally occurring
substances (biochemical pesticides), and pesticidal substances derived from plants containing
added genetic material (plant incorporated protectants). Recent registered global biopesticide
products include bacteria (104 products, mostly are B. thuringiensis), fungi (12 products),
viruses (8 products), nematodes (44 products), protozoa (6 products), and arthropod natural
enemies (107 products) (Waage, 1996). These are used in agriculture for the purposes of insect
, control, disease control, nematode control, etc. Biopesticides are usually inherently less toxic
than conventional pesticides.
Types of Biopesticides
Biopesticides are grouped into three different categories; microbial, plant derived, and
biochemical pesticides.
Microbial Pesticides
Microbial pesticides consist of microorganism such as bacterium, fungus, virus,
protozoan, or alga as its active ingredient. Microbial pesticides can target several different
classes of pests but they are relatively specific for its target pest. The most widely used
microbial pesticides are varieties of the bacterium B. thuringiensis (Bt) which can control large
number of insects in different crops. Bt encodes a protein that is lethal to specific insect pests.
Microbial pesticides need careful monitoring of its application to ensure that they do not
become harmful to nontarget organisms including humans.
Bacteria
Bacillus Thuringiensis (Bt)
B. thuringiensis is a ubiquitous, spore-forming, rod-shaped, Gram-positive bacterium that
encodes large amounts of one or more toxic crystal proteins. B. thuringiensis was discovered
by Ishiwaki in 1901 in diseased silkworm and was subsequently classified and named after its
isolation from the gut of diseased flour moth larvae in Thuringberg, Ernst Berliner. These
proteins are known as Cry protein, δ-endotoxin, or insecticidal crystal protein (ICP) which is
toxic mainly to insect larvae in order Lepidoptera, Diptera, and Coleoptera but isolates with
toxicity toward Homoptera, Orthoptera, Hymenoptera, Mallophaga, and against nematode,
mites, protozoa have also been recently discovered (Lacey & Goettel, 1995). In addition to the
Bt δ-endotoxin, a second class of protein which is lethal against certain insects such as the
alpha-endotoxin, vegetative insecticidal proteins, and several secondary metabolites including
Zwittermycin from Bacillus cereus strains may be used as a defense molecule against different
insects. Various bacterial species and subspecies, especially Bacillus , Pseudomonas , etc., have
been known to be used as biopesticides to control insect and plant diseases. Most important
among these are insecticides which are based on several subspecies of B. thuringiensis . These
subspecies include B. thuringiensis sp. kurstaki and aizawai having toxic activity against
lepidopteran larval species, B. thuringiensis tenebrionis with activity against coleopteran adults
Pg. No. 29 - 33
Biofertilizers
In strict sense, biofertilizers are not fertilizers. They are directly used for supply of
nutrition to crop plants. Microorganisms such as bacteria, fungi, and blue green algae are
largely used as biofertilizers. These organisms are added to the rhizosphere of the plant to
enhance their activity in the soil. They help the plants indirectly through better nitrogen fixation
or improving the nutrient availability in the soil. Their mode of action differs and can be applied
alone or in combination. By systematic research, efficient cultures are identified which are able
to grow in given soil and climatic conditions. Such cultures are prepared at large scale in
laboratory and distributed to farmers. For sufficient shelf-life, they are packed in carrier
materials such as peat and lignite powder. Recently, use of biofertilizers is gaining momentum
due to the increasing importance of maintenance of soil health, reducing environmental
pollution, and the use of harmful chemicals in agriculture. For optimum plant growth, it
requires nutrients in sufficient and balanced amount, but from the soil, only small portion of
nutrients is released each year through biological and chemical processes. Therefore, fertilizers
are used to supplement the nutrients which are already present in the soil (Chen, 2006).
Microorganisms of biofertilizers play a vital role in accelerating the microbial processes such
as controlling soil-borne diseases, improving the soil health, and soil properties. Biofertilizers
can provide an economically viable option to small farmers for realizing the ultimate goal of
increasing crop productivity. These are low-cost, effective and renewable sources of plant
nutrients to supplement chemical fertilizers.
Biopesticides
Biotechnological tools provide solutions to common basic and applied problems that
hinder use of insects’ natural enemies as biological control agents. Commercially, biopesticides
include microorganisms that control pests (microbial pesticides), naturally occurring
substances (biochemical pesticides), and pesticidal substances derived from plants containing
added genetic material (plant incorporated protectants). Recent registered global biopesticide
products include bacteria (104 products, mostly are B. thuringiensis), fungi (12 products),
viruses (8 products), nematodes (44 products), protozoa (6 products), and arthropod natural
enemies (107 products) (Waage, 1996). These are used in agriculture for the purposes of insect
, control, disease control, nematode control, etc. Biopesticides are usually inherently less toxic
than conventional pesticides.
Types of Biopesticides
Biopesticides are grouped into three different categories; microbial, plant derived, and
biochemical pesticides.
Microbial Pesticides
Microbial pesticides consist of microorganism such as bacterium, fungus, virus,
protozoan, or alga as its active ingredient. Microbial pesticides can target several different
classes of pests but they are relatively specific for its target pest. The most widely used
microbial pesticides are varieties of the bacterium B. thuringiensis (Bt) which can control large
number of insects in different crops. Bt encodes a protein that is lethal to specific insect pests.
Microbial pesticides need careful monitoring of its application to ensure that they do not
become harmful to nontarget organisms including humans.
Bacteria
Bacillus Thuringiensis (Bt)
B. thuringiensis is a ubiquitous, spore-forming, rod-shaped, Gram-positive bacterium that
encodes large amounts of one or more toxic crystal proteins. B. thuringiensis was discovered
by Ishiwaki in 1901 in diseased silkworm and was subsequently classified and named after its
isolation from the gut of diseased flour moth larvae in Thuringberg, Ernst Berliner. These
proteins are known as Cry protein, δ-endotoxin, or insecticidal crystal protein (ICP) which is
toxic mainly to insect larvae in order Lepidoptera, Diptera, and Coleoptera but isolates with
toxicity toward Homoptera, Orthoptera, Hymenoptera, Mallophaga, and against nematode,
mites, protozoa have also been recently discovered (Lacey & Goettel, 1995). In addition to the
Bt δ-endotoxin, a second class of protein which is lethal against certain insects such as the
alpha-endotoxin, vegetative insecticidal proteins, and several secondary metabolites including
Zwittermycin from Bacillus cereus strains may be used as a defense molecule against different
insects. Various bacterial species and subspecies, especially Bacillus , Pseudomonas , etc., have
been known to be used as biopesticides to control insect and plant diseases. Most important
among these are insecticides which are based on several subspecies of B. thuringiensis . These
subspecies include B. thuringiensis sp. kurstaki and aizawai having toxic activity against
lepidopteran larval species, B. thuringiensis tenebrionis with activity against coleopteran adults
