Transcript Corn steep liquor

Culture Media
• Culture Medium: Nutrients prepared for
microbial growth
• Sterile: No living microbes
• Inoculum: Introduction of microbes into
medium
• Culture: Microbes growing in/on culture
medium
Agar
• Complex polysaccharide
• Used as solidifying agent for culture media in
Petri plates, slants, and deeps
• Generally not metabolized by microbes
• Liquefies at 100°C
• Solidifies ~40°C
Culture Media
• Chemically Defined Media: Exact chemical
composition is known
• Complex Media: Extracts and digests of
yeasts, meat, or plants
– Nutrient broth
– Nutrient agar
Culture Media
Table 6.2 & 6.4
Anaerobic Culture Methods
• Reducing media
– Contain chemicals (Thioglycollate or oxyrase)
that combine O2
– Heated to drive off O2
• Fluid Thioglycollate broth is a reducing
medium. It contains sodium thioglycollate ,
which reacts with molecular oxygen keeping free
oxygen levels low.
• The sodium thioglycollate in the broth creates a
redox potential in the tube, with higher levels of
oxygen at the top of the tube, and a complete
absence of oxygen at the bottom of the tube.
• Fluid thioglycollate broth also typically contains
a redox potential indicator such resazurin ,
which produces a pink color in an oxidized
environment.
Thioglycollate Broth
Tube 1 :Obligate Anaerobe -- note the absence of growth in the top portion of the
broth where oxygen is present.
Tube 2 :Obligate Aerobe -- note the growth is only in the top portion of the tube
where oxygen is present.
Tube 3 :Aerotolerant -- note the uniform growth from top to bottom.
Tube 4 :Facultative -- note the uneven distribution of growth from top to bottom
(more growth at the top.)
Tube 5 :Obligate Aerobe -- note the growth is only in the top portion of the tube
where oxygen is present.
Anaerobic Culture Methods
• Anaerobic
jar
anaerobic jar is an
instrument used in the
production of an anaerobic
environment. This method of
anaerorbios is as others is
used to culture bacteria
which die or fail to grow in
presence of oxygen
Sodium bicarbonate and sodium borohydride
are mixed with a small amount of water to
produce CO 2and H .+
A palladium catalyst in the jar combines with the
O 2in the jar and the H +to remove O .2
Figure 6.5
Anaerobic Culture Methods
• Anaerobic
chamber
Figure 6.6
Capnophiles require high CO2
• Candle jar
• CO2-packet
Figure 6.7
Selective Media
• Suppress
unwanted
microbes and
encourage
desired microbes.
Figure 6.9b, c
Differential Media
• Make it easy to distinguish colonies of
different microbes.
Figure 6.9a
Enrichment Media
• Encourages growth of desired microbe
• Assume a soil sample contains a few
phenol-degrading bacteria and thousands of
other bacteria
– Inoculate phenol-containing culture medium with
the soil and incubate
– Transfer 1 ml to another flask of the phenol
medium and incubate
– Transfer 1 ml to another flask of the phenol
medium and incubate
– Only phenol-metabolizing bacteria will be
growing
• A pure culture contains only one species
or strain
• A colony is a population of cells arising
from a single cell or spore or from a group
of attached cells
• A colony is often called a colony-forming
unit (CFU)
Streak Plate
Figure 6.10a, b
Industrial Media and the Nutrition
of Industrial Organisms
THE BASIC NUTRIENT REQUIREMENTS
OF INDUSTRIAL MEDIA
• Carbon or energy requirements
• Nitrogen is found in proteins including
enzymes as well as in nucleic acids
• Minerals
• Growth Factors
Average composition of
microorganisms (% dry weight)
CRITERIA FOR THE CHOICE OF RAW
MATERIALS USED IN INDUSTRIAL MEDIA
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Cost of the material
Ready availability of the raw material
Transportation costs
Ease of disposal of wastes resulting from the
raw materials
Uniformity in the quality of the raw material
and ease of standardization
Adequate chemical composition of medium
Presence of relevant precursors
Satisfaction of growth and production
requirements of the microorganisms
SOME RAW MATERIALS USED IN
COMPOUNDING INDUSTRIAL MEDIA
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Corn steep liquor
Pharmamedia
Distillers soluble
Soya bean meal
Molasses
Sulfite liquor
Other Substrates (alcohol, acetic acid,
methanol, methane, and fractions of crude
petroleum)
Corn steep liquor
• This is a by-product of starch manufacture
from maize.
• As a nutrient for most industrial organisms
corn steep liquor is considered adequate,
• rich in carbohydrates, nitrogen, vitamins,
and minerals.
• highly acidic, it must be neutralized
(usually with CaCO3) before use.
Approximate composition of corn
steep liquor (%)
Pharmamedia
• Yellow fine powder made from cotton-seed
embryo.
• It is used in the manufacture of
tetracycline and some semi-synthetic
penicillins.
• rich in protein, (56% w/v) and contains
24% carbohydrate, 5% oil, and 4% ash
• rich in calcium, iron, chloride,
phosphorous, and sulfate.
Distillers soluble
• By-product of the distillation of alcohol
from fermented grain. (maize or barley)
• It is rich in nitrogen, minerals, and growth
factors.
Composition of maize distillers
soluble
Soya bean meal
• The seeds are heated before being extracted for oil that
is used for food, as an antifoam in industrial
fermentations, or used for the manufacture of margarine.
• The resulting dried material, soya bean meal, has about
11% nitrogen, and 30% carbohydrate and may be used
as animal feed.
• Its nitrogen is more complex than that found in corn
steep liquor
• Not readily available to most microorganisms, except
Actinomycetes.
• It is used particularly in tetracycline and streptomycin
fermentations.
Molasses
Sulfite Liquor
• Sulfite liquor (also called waste sulfite liquor,) is the
aqueous effluent resulting from the sulfite process for
manufacturing cellulose or pulp from wood.
• During the sulfite process, hemicelluloses hydrolyze and
dissolve to yield the hexose sugars, glucose, mannose,
galactose, fructose and the pentose sugars, xylose, and
arabinsoe.
• Used as a medium for the growth of microorganisms after
being suitably neutralized with CaCO3 and enriched with
ammonium salts or urea, and other nutrients.
• It has been used for the manufacture of yeasts and
alcohol.
• Some samples do not contain enough assaimilable
carbonaceous materials for some modern fermentations.
• They are therefore often enriched with malt extract, yeast
autolysate, etc.
GROWTH FACTORS
• Not synthesized by the organism
• Must be added to the medium.
• Function as cofactors of enzymes and
may be vitamins, nucleotides etc.
• The pure forms are usually too expensive
for use in industrial media
• Growth factors are required only in small
amounts.
Some sources of growth factors