naturally, such as a *polysaccharide,
*protein, or *nucleic acid.
bioreactor (industrial fermenter) A
large stainless steel tank used to
grow producer microorganisms in
the industrial production of enzymes
and other chemicals. After the tank
is steam-sterilized, an inoculum of
the producer cells is introduced into
a medium that is maintained by
probes at optimum conditions of
temperature, pressure, pH, and oxygen levels for enzyme production. An
agitator (stirrer) mixes the medium,
which is constantly aerated. It is essential that the culture medium is
sterile and contains the appropriate
nutritional requirements for the
microorganism. When the nutrients
have been utilized the product is separated; if the product is an extracellular compound the medium can be
removed during the growth phase of
the microorganisms, but an intracellular product must be harvested
when the batch culture growth stops.
Some bioreactors are designed for
continuous culture.
biosensor A device that uses an immobilized agent to detect or measure
a chemical compound. The agents include enzymes, antibiotics, organelles, or whole cells. A reaction
between the immobilized agent and
the molecule being analysed is transduced into an electronic signal. This
signal may be produced in response
to the presence of a reaction product,
the movement of electrons, or the
appearance of some other factor (e.g.
light). Biosensors are being used increasingly in diagnostic tests: these
allow quick, sensitive, and speciÜc
analysis of a wide range of biological
products, including antibiotics, vitamins, and other important biomolecules (such as glucose), as well as the
determination of certain *xenobiotics, such as synthetic organic compounds.
biosynthesis The production of
molecules by a living cell, which is
the essential feature of *anabolism.
biotechnology The development
of techniques for the application of
biological processes to the production of materials of use in medicine
and industry. For example, the production of antibiotics, cheese, and
wine rely on the activity of various
fungi and bacteria. Genetic engineering can modify bacterial cells to synthesize completely new substances,
e.g. hormones, vaccines, monoclonal
antibodies, etc., or introduce novel
traits into plants or animals.
biotin A vitamin in the *vitamin B
complex. It is the *coenzyme for various enzymes that catalyse the incorporation of carbon dioxide into
various compounds. Adequate
amounts are normally produced by
the intestinal bacteria; other sources
include cereals, vegetables, milk, and
liver.
biotite An important rock-forming
silicate mineral, a member of the
*mica group of minerals, in common
with which it has a sheetlike crystal
structure. It is usually black, dark
brown, or green in colour.
bipy See dipyridyl.
bipyramid See complex.
bipyridyl See dipyridyl.
biradical (diradical) A radical that
has two unpaired electrons at different points in the molecule, so that
the radical centres are independent
of each other.
birefringence See double refraction.
Birge–Sponer extrapolation A
method used to calculate the heat of
bioreactor
72
b
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*protein, or *nucleic acid.
bioreactor (industrial fermenter) A
large stainless steel tank used to
grow producer microorganisms in
the industrial production of enzymes
and other chemicals. After the tank
is steam-sterilized, an inoculum of
the producer cells is introduced into
a medium that is maintained by
probes at optimum conditions of
temperature, pressure, pH, and oxygen levels for enzyme production. An
agitator (stirrer) mixes the medium,
which is constantly aerated. It is essential that the culture medium is
sterile and contains the appropriate
nutritional requirements for the
microorganism. When the nutrients
have been utilized the product is separated; if the product is an extracellular compound the medium can be
removed during the growth phase of
the microorganisms, but an intracellular product must be harvested
when the batch culture growth stops.
Some bioreactors are designed for
continuous culture.
biosensor A device that uses an immobilized agent to detect or measure
a chemical compound. The agents include enzymes, antibiotics, organelles, or whole cells. A reaction
between the immobilized agent and
the molecule being analysed is transduced into an electronic signal. This
signal may be produced in response
to the presence of a reaction product,
the movement of electrons, or the
appearance of some other factor (e.g.
light). Biosensors are being used increasingly in diagnostic tests: these
allow quick, sensitive, and speciÜc
analysis of a wide range of biological
products, including antibiotics, vitamins, and other important biomolecules (such as glucose), as well as the
determination of certain *xenobiotics, such as synthetic organic compounds.
biosynthesis The production of
molecules by a living cell, which is
the essential feature of *anabolism.
biotechnology The development
of techniques for the application of
biological processes to the production of materials of use in medicine
and industry. For example, the production of antibiotics, cheese, and
wine rely on the activity of various
fungi and bacteria. Genetic engineering can modify bacterial cells to synthesize completely new substances,
e.g. hormones, vaccines, monoclonal
antibodies, etc., or introduce novel
traits into plants or animals.
biotin A vitamin in the *vitamin B
complex. It is the *coenzyme for various enzymes that catalyse the incorporation of carbon dioxide into
various compounds. Adequate
amounts are normally produced by
the intestinal bacteria; other sources
include cereals, vegetables, milk, and
liver.
biotite An important rock-forming
silicate mineral, a member of the
*mica group of minerals, in common
with which it has a sheetlike crystal
structure. It is usually black, dark
brown, or green in colour.
bipy See dipyridyl.
bipyramid See complex.
bipyridyl See dipyridyl.
biradical (diradical) A radical that
has two unpaired electrons at different points in the molecule, so that
the radical centres are independent
of each other.
birefringence See double refraction.
Birge–Sponer extrapolation A
method used to calculate the heat of
bioreactor
72
b
www.AzShimi.ir www.AzShimi.com