Oxygen requirements

how much oxygen?

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

How is oxygen detoxified?

what enzymes?

what are their chemical reactions?

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

To increase carbon dioxide.

Carbon dioxide incubators-similar to human bodies

Candle jar-increases CO₂

Reducing Media-used to grow pathogenic organisms

Cultivation of anaerobes

creating environments

Anaerobic growth chamber-hydrogen combines with oxygen

Anaerobic incubator- oxygen is replaced with N₂ gas

Reducing Media-Thioglycollate broth

Phases of growth

and equation

N_t=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.

Ways to measure bacterial growth.

devices that help count microbial growth

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.

Bactercult?

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

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.

Temperature and the effects on organisms.

organisms that live in certain temperature conditions.

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

pH and organisms

pH and what lives in different conditions

Neutrophiles- like neutral envrionments 5.5-8.5

Acidophiles-like acidic environments 5.5 and below

Alkalophiles- basic environments 8.5 and above

Extreme halophiles

def.-loves salt 15% NaCl

ex:Staphylococcus

Facultative halphiles

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

Ex.-E.Coli

Nutritional Factors effecting microbial growth

what do microbes need?

what are their names and what do they use?

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.

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

Energy source

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

Phototrophs-derives energy from light

Carbon sources and energy sources organisms combinations

Chemical and Carbon sources:

Light and Carbon sources:

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.

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

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.

needeed for amino acids and nucleotides

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

Nitrogen-fixing bacteria-obtain N from N₂ in atmosphere