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chapter 7 microbial growth
microbial growth
16
Microbiology
Undergraduate 1
09/18/2009

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Cards

Term

Oxygen requirements

how much oxygen?

Definition

Obligate aerobes-oxygen required

Facultative aerobes-greater growth in o2 but not needed

Obligate anaerobes-no oxygen, anarobic growth

Aerotolerant anaerobes-will continue to grow in o2

Microaerophiles-oxygen in small quanities

 

Term

How is oxygen detoxified?

what enzymes?

what are their chemical reactions?

Definition

Superoxide Dismutase(SOD)- Removes superoxides(oxygen free radicals)

2O2-+2H+->H2O2+O2

Catalase-removes Hydrogen peroxide

2H2O2->2H2O+O2

Peroxidase-removes hydrogen peroxide

H2O2+2H+->2H2O

 

Term
Providing Appropriate Oxygen Conditions..
Definition

To increase carbon dioxide.

Carbon dioxide incubators-similar to human bodies

Candle jar-increases CO2

Reducing Media-used to grow pathogenic organisms

Term

Cultivation of anaerobes

creating environments

 

 

Definition

Anaerobic growth chamber-hydrogen combines with oxygen

Anaerobic incubator- oxygen is replaced with N2 gas

Reducing Media-Thioglycollate broth

Term

Phases of growth

and equation

Definition

Nt=N0(2n)

Lag Phase-organisms are taking up nutrients and are getting ready to divide. number doesnt change.

Log Phase-Binary fission is occuring, very active number increases significantly.

Stationary-nutrients are becoming scarse rate of growth decreases. number of cells dividing and the number of cells dying are equal.

Death-nutrients are running out, rate of death is higher than rate of division. waste build up.

 

Term

Ways to measure bacterial growth.

devices that help count microbial growth

Definition

Direst count-counting chamber

Viable count-plate count method

-filtration

Indirect-turbidity

-spectrophotometer-bacteria is placed in a vial and total number is counted by a machine

high turbidity-high number of organisms present

this meathod is fast but it also counts dead organisms.

 

Term

Bactercult?

what does a bactercult do? what is in a bactercult?

Definition

used to test for UTI, identify organisms in urine

ingredients.. phenol red, peptone and lactose.

Advantage-can count the number of colonies and estimate the number of bacteria in urine.

Term

Temperature and the effects on organisms.

organisms that live in certain temperature conditions.

Definition

Psychrophiles-cold loving 5-15*C

Psychrotrophs-will grow in refridge. but prefers20-30*C

Mesophiles-moderate termperatures 25-40*C

Thermophiles-heat loving 50-60*C

Hyperthermophiles-extreme heat >80*C

Term

pH and organisms

pH and what lives in different conditions

Definition

Neutrophiles- like neutral envrionments 5.5-8.5

Acidophiles-like acidic environments 5.5 and below

Alkalophiles- basic environments 8.5 and above

Term
Bacteria and Osmotic pressure(salty environments)
Definition

Extreme halophiles

def.-loves salt 15% NaCl

ex:Staphylococcus

Facultative halphiles

Def.-2%-15% NaCl can live in salty conditons

Ex.-E.Coli

Term

Nutritional Factors effecting microbial growth

what do microbes need?

what are their names and what do they use?

Definition

includes:carbon, nitrogen and energy sources

*have to have one ol each*

Carbon:

Autotrophs-carbon dioxide gas CO2 "self feeders

Heterotrophs-obtains carbon from organic molecules such as sugars, proteins, nucleic acids and lipids.

Term

Nutritional  Factors affecting microbial growth cont.......

Energy source

Definition

Chemotrophs-chemical reactions for energy sources (ATP!! repiration and fermentation)

Phototrophs-derives energy from light

Term

Carbon sources and energy sources organisms combinations

Chemical and Carbon sources:

Light and Carbon sources:

Definition

Chemical and Carbon sources:

Chemoautotrophs:use chemicals and carbondioxide

Chemoheterotrophs:use chemicals and organic molecules

Light and Carbon sources:

Photoautotrophs: use light and carbon dioxide

Photoheterotophs:use light and organic molecules.

Term
Photoautotrophs
Definition

2Use:light and carbon dioxide

some use oxygenic photosynthesis(use light as a catalyst)

Reaction:

12H2O+6CO2->C6H12O6+6H2O+6O2

ex:plants, algae, cyanobacteria or"blue-green algae"

Cyanobacteria:

converts nitrogen gas into nitrate and ammonia for food "nitrifying bacteria"

-important bacteria to have in soil

-plants use the nitrate and ammonia for food

-thses bacteria have a relationship with legumes

 

Term
Chemoautotrophs
Definition

use:carbon dioxide and inorganic molecules for energy(hydrogen gas, hydrogen sulfide, nitrite)

ex: archaea(methanogens produce methane gad using hydrogen gas) some organism live in the gi tracts of animals in anaerobic conditions.

Term
Nitrogen Sources
Definition

needeed for amino acids and nucleotides

obtains from proteins, ammonium ions(NH4+), and nitrites(NO3-)

Nitrogen-fixing bacteria-obtain N from N2 in atmosphere

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