Nutrition Nutrition is a process by which chemical substances
called nutrients are required from the environment and used for the
cellular activities of metabolism and growth. Nutrient the
substance could be used by microbes for metabolism or reproduction
of cells.
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Nutrient provide the structural substance, energy, metabolic
regulate substance and appropriate physiological environment. Some
microbes could use nonmaterial energy---light.
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I. cellular chemical constitutes Its much alike in the life in
the element. The main elements are C H O N (90%---97% to total dry
cell weight), C is about 50%, the others are inorganic nutrient.
C/N is 5:1 usually. Section 1 Six kinds of essential nutrient for
microbes
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element Macronutrient C H O N P S others element K Na Ca Mg Fe
Mn Cu Co Zn Mo, et al Existence form: organic protein sugar lipoid
nucleic acid vitamin decomposition substance metabolic medial
products inorganic salt ash Water---70% ~ 90% to wet cell
weight
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elementbacteriayeastmould C5049.847.0 N157.55.2 H85.76.7
O2031.140.2 P31.51.2 S10.30.2 Table 1.The macronutrient content in
microbes (% to dry cell weight)
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The substance utilized by generic species could be utilized by
microbes too. The substance couldn t be utilized by generic species
could be utilized by microbes. Some kinds of substance harmful to
generic species also could be utilized by microbes. Microbes is
omnivorous.
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II. Main nutrient and the function Carbon source Nitrogen
source Energy source Growth factor Inorganic salt Water
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Functions: vconstitute the cells of the microbes vprovide the
energy needed in the physiological activity to microbes vthe source
to form the microbial metabolic products Nutrient is the substance
base for microbial metabolism and living activity. If lose this
base, the life will die.
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Heterotrophic microbe: is an organism must obtain its carbon in
an organic form. Autotrophic microbe: is an organism that uses CO
2, an inorganic gas, as its carbon source. 1.Carbon sources The
nutrient provide the carbon element for microbies Organic carbon
sources: protein, nucleic acid, starch, glucose, et al Inorganic
acid: CO 2, Na 2 CO 3, CaCO 3 et al
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the carbon sources could be utilized by microbes (compound)
saccharide glucose fructose maltose sucrose starch galactose
lactose mannancellulose hemicellulose lignin et al organic acid
lactic acid citric acid short chain fatty acid long chain fatty
acid amino acid et al alcoholic aldehyde ethanol et al fat fat
lecithoid et al hydrocarbon natural gas petroleum olefin et al CO2
carbonate NaHCO3, CaCO3, chalk et al others cyanide protein peptide
nucleic acid
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organic nitrogen sources peptone soybean powder maize slurry
inorganic nitrogen sources NH 4 NO 3 (NH4) 2 SO 4 gas nitrogen
sources N 2 in the atmosphere 2. Nitrogen sources The nutrient
provide the nitrogen element for microbes. Normally,nitrogen source
couldnt be used as energy sources. quick nitrogen sources slow
nitrogen sources
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energy sources are the substances or radiant energy that could
provide primal energy sources. Heterotrophss carbon sources could
also be its energy sources. 3. Energy sources Inorganic:energy to
chemoautotrophs Energy sources table Chemical substances Radiant
energy energy to photoautotrophs and photoheterotrophs. Organic:
energy to chemoheterotrophs
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mono-function : radiant energy di-function: reductive inorganic
nutrient,such as NH 4 + is the energy sources as well as the
nitrogen sources of nitrate bacterial. triple function: the
nutrients including N C H O are energy sources carbon sources and
nitrogen sources heterotrophs microbes. one kind of nutrient could
provide more than one kind of function
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Definition:An organic compound such as an amino acid, nitrogen
base, or vitamin that cannot be synthesized by an organism and must
be provided as a nutrient is a growth factor. Sources of growth
factors in culture medium: yeast extract maize slurry wort,et al 4.
Growth factor Function coenzyme or necessary to activation of
enzyme.
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narrow sense vitamin broad sense vitamin, amino acid, base,
fatty acid,et al auxoautotrophs auxoheterotrophs nutritional
deficiency mutant auxo-excessivetrophs
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vitaminspecies thiamin B 1 Bacillus anthracis
lactoflavinClostridium tetani nicotinic acidBrucella abortus
vitamin B 6 Lactobacillus spp. biotinLeuconostoc mesenteroides
pantothenic acidProteus morganii folacinLeuconostoc dextranicum B
12 Lactobacillus spp. vitamin KBacteroides melaninogenicus Vitamin
necessary to some bacterials
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5. Inorganic salts Macroelement: need the concentration of the
element at 10 -3 -10 -4 M Microelement: need the concentration of
the element at 10 -6 -10 -8 M
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The physiology function for inorganic salts inorganic salts
Macroelement Microelement Usual function Especial function Normal
molecular in cell(P S Ca Mg Fe) Physiology modulation material
maintain osmotic pressure (Na + ) enzyme activator(Mg 2+ ) stablize
pH Energy sourse of chemoautotrophic bacteria (S Fe 2+ NH 4 + MO 2
- ) Hydrogen aceptor during respiration without oxygen (NO 3 - SO 4
2- ) Enzyme activator (Cu 2+ Mn 2+ Zn 2+ ) Molecular of special
structure (Co Mo)
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Physiological function cell composition solvent of biochemistry
reaction chemical and physiological reaction medium material
transferred medium regulate cell temperature maintain osmotic
pressure 6.Water existed state:dissociated state(solvent)and
integrated state(structure composition)
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based on different carbon sources heterotrophs: cant use CO 2
as its mainly or sole carbon energy autotrophs: can use CO 2 as its
mainly or sole carbon energy Section 2 Nutrition types of microbes
based on different energy sources phototrophs: obtain energy from
light chemotrophs:obtain energy by oxidation based on growth factor
prototroph or wild type auxotroph Classification
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Nutrition type of microbe Nutrition typeEnergy sourceCarbon
sourceexample photoautotr ophs sunlightCO 2 Cyanobacterial Purple
bacterial Green sulfur bacterial Algae photohetero trophs sunlight
CO 2 and simple organic compounds Rhodospirillum chemoautot rophs
inoganic compounds CO 2 Nitrobacterial Sulfbacterial Ironbacterial
Hydrobacteri al chemoheter otrophs organic compounds Most microbes
Prozotoa
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parasitism live in live organisms. saprophytismlive in dead
organic. Chemoheterotrophs to note that such classification is not
absolute and it may be changed under different conditions
heterotrophs are dependent on other life forms can live normally
with at least one kind of organic compound its carbon soueces and
hydrogen supplier should be in organic form energy can be obtained
by oxidation and absorption of sunlight. autotrophs can live
normally without any organic compounds.
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Section 3 Transport mechanisms for nutrient absorption The
absorbtion of nutrient and excretion of metabolized products refer
to transportion of molecular nutrient absorbed in cell and be used
metabolized products secreted out of the cell,that is the whole
process of transportion. The cell wall can only block large
molecular solute (>600Da) out of the cell, while the membrane
which have lipid bilayer and integral protein is the main barrier
to control the nutrient s flow.
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permeability is different from absorbtion commonly,large
molecular first hydrolyze to small molecular,then be aborbed.
fat-dissolved easily permeable ionization the weaker of polar,the
faster of the permeable
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I. Simple diffusion The rate of diffusion is directly
proportional to the concentration gradient of the molecule across
the membrane. Do not acquire metabolic energy, is of no
specificity. Only transformed small molecular,O2 CO2 glycerol
ethanol and some amino acids Lipohilia molecules make use of the
permeability of cell membrane to transport from high concentration
to the low concentration.
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II. Facilitated diffusion The transported molecular in and out
of the cell have different appetency to the carrier protein.
characteristic Require the presence of specific carrier protein,
down the concentration gradient Require the presence of specific
carrier protein, down the concentration gradient Do not acquire
metabolic energy Transport SO4, PO3, sugars
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Carrier protein: namely permeable enzyme mostly are induction-
enzyme is specific for one particular molecular or a group of
structurally similar moleculars. It can make the transportion
faster,but is not able to make it against the concentration
gradient.
Concentration gradient Transportion rate Prapartion of simple
diffusion and facilitated diffusion
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simple diffusion facilitated diffusion and active transport the
transported solute wont be changed. III. Active transport
characteristics characteristics The main mode for microbes to
absorb nutrient Against the concentration gradient,require energy
Need barrier protein, is specific Transport organic iron inorgnic
iron amino acid lactose and other sugars Need energy to change the
conformation of barrier protein Appetence change protein
conformational changeconsume energy
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intracellular Extracellula r(outsidr the plasma membrane)
election transfer 1. Use electron transfer to pump the proton to
extracellular 2. Expel Na + out of membrane by reverse transport
mechanism 3. Na + combine with barrier protein complex 4. The form
of combination site changed,to combine with the solute
(eg:sugar,amino acid) 5. Barrier protein conformational change,
release Na + in theintrecellular,then solute separate from barrier
protein. Mechanism of active transport use the gradient of H + and
Na +
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characteristic characteristics belong to active transport
solute molecular have chem-modification directional phosphorylation
need a complicated series of transport enzyme to transform glucose
fructose mannan purin nucleotide fatty acid,et al IV. Group
translocation The membrane has high impermeability to most
phosphate compounds. Input each glucose may consume one ATP.
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Mainly depend on PEPand PTS. PEP+ HPr EI Pyruvic acid+ P-HPr
P-HPr +saccharide EII saccharide-P+HPr 1. Activate the heat stable
carrier protein (HPr) 2. Saccharide transferred into membrane after
phosphorylation
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Transport of glucose group translocation 2 kinds of systems of
PEP and PTS system. High-energy phosphate transfer from HPr to
dissolved EIIA, EIIA combines with EIIB mannan transport system and
separate in the glucose transport system.No matter in which
form,phosphate will first transfer from EIIA to EIIB,and arrive at
glycosyl by the process of transport across membrane. cytoplast
Cytoplasm stroma
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I. Definition: medium culture medium Culture medium is the
mixed nutrient suitable for microbes growth and breed. Section 4
culture medium
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A. Four principles 1. Definite aims different microbes have
different nutrient requirement : to culture which microbes to get
which products useless II. Principles and methods to select and
make culture medium 2. Suitable nutrients: pay attention to the
concentration and ratio of nutrients especially C/N ratio
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C/N ratio: mol ratio of carbon atom in carbon sources and
nitrogen atom in nitrogen sources. C/N ratio in most medium:100/0.5
2. Nitrogen content % NH 3 (82%)>CO(NH 2 ) 2 (46%)>NH 4 NO 3
(35%)>(NH 4 ) 2 CO 3 (29.2%)>(NH 4 ) 2 SO 4 (21%)
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Selection of suitable nutrient kindexampleexplaiation
monosaccharidesglucose,maltose,xylose,galactose, fructose used as
quick carbon sources,but will speed up breathof microbe,decrease
resolved O 2,make mid-metabolized products accumulate.
disaccharidesaccharose,lactoseUsed as slow carbon sources, but will
speed up breathof microbe,decrease resolved O 2,make
mid-metabolized products accumulate.
polysaccharidestarch,cornmeal,celluloseslow carbon sources,only few
microbes canuse cellulose as carbon sources molassesSugar beet
molasses, sugancane molasses. good carbon sources,
complicated,usually fermented from yeast in fermentation
industry,widely used in the production of antibiotic acetone and
butanol.usually include saccharose 35%,glucose 9%, fructose 7%,
8kingsother sugars 4%,other deoxidized materials3%,24 kinds amino
acid 4.5%,organic acid 5%,wax steroids and phosphorous0.4%, ash
12%,water20%. maltbudded barleymainly used to culture yeast,can be
used to prouduce beer in industry grease cottonseed oil, corn
oil,bean oil,sunflower seed oil high ,consume more O 2 when
cultured in liquid,usually added as in industry
alcoholsmethanol,glycerolMethanol canbe used to culture yeast
hydrocarbonCH 4,C 2 H 4,C 4 H 10,C 12 ~C 20 high , consume more O 2
when cultured in liquid.hardly dissolved,don t too much beating up
when cultured in liquid. organic acidacetic acid, lactic
acid,citric acidwill increase the pH
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carbon sources stroma glucosemethane Normal paraffin hydrocar
bon methanolethanolacetate fumarat e cell producing efficiency( g
cell/g stroma) 0.510.621.030.400.680.340.36 Cell yield by different
energy source
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Common nitrogen sources for microbe KindsSuitable
microbeCharacteristic organic :beaf extract,yeast extract, peanut
cake power,soybean poder,cotton cake power,maize slurry,maize
protein power, peptone,yeast power,fish meal,silkworm pupa
power,wheat bran Most microbes,eg:Penicillium,ye ast,E.coli contain
plenty of amino acid,good nitrogen sources for microbes inorganic:
ammonium salt nitrate, ammonia Part of microbes(amino acid
heterotrophs aren t able to use it) Nitrate can be used after
deoxidization,may regulate pH meantime. N2N2 few bacteria
(approximately 50 genus, 100 species) Nitrogen fixation is second
important only to photosynthesis.
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pH osmotic pressure and water ability redox potential 3.
Suitable chemical and physical conditions:
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pH most suitable pH v bacteria: pH7.0~8.0 v actinomyces pH7.0
~8.5 v yeast: pH3.8~6.0 v mould pH4.0~6.0 pH value in the medium
could change in the growing process of microorganisms v If culture
in stroma containing carbohydrate,produce acid,so the pH will
decrease. v If decompose protein and amino acid, produce NH3,pH
will increase. v If use (NH4)2SO4 as nitrogen sources, SO4 2- will
be excessive,so the pH decrease. v If decompose positive iron
compounds,eg:NaNO3, Na+ will be excessive,so the pH increase.
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methods to maintain medium pH stable Use phosphorus buffer K 2
HPO 4 /Na 2 HPO 4, H 2 PO 4 /NaH 2 PO 4 K 2 HPO 4 /Na 2 HPO 4, H 2
PO 4 /NaH 2 PO 4 Usestandby alkali CaCO3 CaHCO 3 Use acidesecent
salt citrate lactophosphate et al Use liquid N2 or HCl.
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Osmotic pressure:pressure produced by solutes, when filterring
from high concentration to low cocentration Hypertonic solution
will cause plasmolysis. Hypotonic solution will make cell expand or
even break.
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Utilized ability of water water activity, aw aw the quantity of
free or dissociated water that microbes can utilize under natural
environment. Its eaqual to the ratio of saturated steam pressure of
the solution and pure water, in the same temperature and pressure..
aw =P/Po P: steam pressure of the solution Po: steam pressure of
pure water aw of pure water is 1.00,under normal temperature and
pressure Suitable aw to microbes growth is 0.6 0.998.
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solution awaw 30% glucose 0.964 1% glucose +20%glycerol 0.955
1% glucose +40%saccharose 0.964 Saturated NaCl 0.78 Saturated CaCl
2 0.30 Saturated MgCl 2 0.30 Saturated LiCl 0.11 A w of some
solution
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Eh redox potential to show the trend of reducer releasing
electron or oxidant accepting eletron in the redox system. Aerobes
+ 0.1V Generally +0.3~ +0.4V Anaerobes < + 0.1 Facultative
anaerobes < +0.1 fermentation >+0.1 aerobic respiration
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4. Appropriate raw material veconomy principle:use the low
grade replacing high grade,use the waste replacing normal
material,use the simple replacing complex veasily treated,with low
cost v produce little waste after treated
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Sterilization Sterilization under high pressure 1.05kg/cm 1210C
15 30min Sterilization under high temperature may destroy some
nutrients and change the pH.
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B. Four methods Ecological simulation Lookup literature
Elaborate Experiment Comparison
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Category of Culture medium Based on the component of the
culture medium Complex medium ( or Undefined medium ) Complex
medium is one kind of culture mediums, which utilizes animal/
plant/micro-organism or the extract from these substance, and the
components are undefined, e.g. broth peptone medium,which is a
growth medium for bacteria; malt extract medium,which is a growth
medium for yeast. Advantages convenience; be rich in nutrition;
variety
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Defined medium ( or Synthetic medium ) Defined medium is one
kind of the culture mediums, which is compounded by many pure
chemical reagent, and the components ( including the microelement )
are defined exactly, e.g. Glu-NH 4 + medium, which is a growth
medium for bacteria; Starch-NO 3 - medium, which is a growth medium
for actinomycete. Expensive be used in research( metabolism
analysis/ genetic analysis) Advantages The component is exact;
Well-repeat Semi-defined medium
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Solid medium : add solidifying agents; the content of
solidifying agents is 1 2 . sterilization; good-diaphaneity;
convenience; cheap. Condition of being the solidifying agents: Cant
be utilized or decomposed by microbe; can keep the solid condition
in the growth temperature range; It isnt harmful for microbe at
solidification point temperature; cant be destoried by
sterilization; good-diaphaneity; convenience; cheap. Solidifying
agents that we always use: Agar and Glutin Usage:
isolation/identification/conservation of the strain (Solid medium
allows the surface to form mono-colony ) Base on the physical
condition of culture medium:
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Semi-solid medium: the content of solidifying agents is 0.5%
Usage: observe the motion of bacteria; mensurate the titer of
bacteriophage. Usage: observe the motion of bacteria; mensurate the
titer of bacteriophage. Liquid medium : no solidifying agent Usage:
microbe culture the research on physiology /Metabolism Usage:
microbe culture the research on physiology /Metabolism
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The Difference between Agar and Glutin
ChemistryComponentNourish-mentResolv-abilityMelttemperatureSolidificationtemperatureConcent-rationDiaphaneity
Adhesio n value Tolerance of Sterilization under high pressure Agar
polysaccha- ride polymernone infrequen t 96 40 1.5~2 % highbighigh
Glutinproteinnitrogensourceeasy 25 20 5~12 % highbiglow
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E. Coli growed in EMB (Eosin Methylene Blue) Culture, can
decompose lactose and produce much mixed acid. The thallus carry
with H +, so acidic chromophore Eosin is attracted to the
positively charged molecules of E.coli. Eosin can combine with
Methylene Blue, which makes the colonies purple. Green metallic
luster is observed from the surface glisten of colonies. Colonies
that ferment lactose are red and colonies that produce acid weakly
are brown, whereas non-fermenters are transparent. EMB (Eosin
Methylene Blue) Culture medium identified enteric bacterial
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EMB (Eosin Methylene Blue) Culture medium
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Brief Summary 1 Microorganisms need about 10 kinds of
macroelement part of them are used to form carbohydrate lipid
protein nucleic acid,others are bittly used as coenzyme and
prosthetic group. 2 All the microorganisms can be classifed on the
basis of their needness of carbon courses energy sources hydrogen
atom and electron. 3 Nutrients cant permeated through cytoplasm
membrane persistently by passive transport,they must choose one
kind of active transport mechanism to do so. Medium are necessary
to culture microbe.You may need to filtrate or separate special
microbes in microorganisms identification water quality appraisal
food analysis and so on,remember different aim determines different
medium.
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Reviewing question of this chapter 1 What are the macroelement
and microelement? 2 How many kinds of macroelements are needed by
microbes? 3 What is nutrition,what is nutrient,What physiological
function does the nutrient have 4 Try to compare the similarities
and differences about nutrients and nutriention mode among animals
plants and microorganisms. 5 What are carbon sources?List some
carbon sources commonly used by microbes. 6 Find the differences on
the using of carbon sources by microbes. 7 What are nitrogen
sources List some nitrogen sources commonly used by microbes.
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8 What are the characteristic of the using of nitrogen sources
by microbes 9 What is amino acid autotrophs,what is amino acid
heterotrophs 10 Try to compare the differences of the way that
nutrients use to get into cell. 11 What is culture medium and what
is complex medium 12 What is semi-solid medium 13 What is
differential medium?Give an example of this kind of medium and
explain its principle. 14 What is the C N ratio 15 What are the
basic principles to make medium?
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References Zhou Deqin Microbiological Tutorial 2002, second
edition higher education press Kathleen Park Talaro,fundations in
microbiology,2005, fifth edition, higher education press