microbiology exam 2

Physical Requirements

1. Temperatrue

Psychrotrophs

-can grow at 0c
-Highest good temp. 20-30 not above 40
found in refrigerator food spoilage

Psychrophiles (cold-loving)

-can grow at 0
-good grow temp. 15
-found in polar regions

Mesophiles (moderate temp. loving)

-good temp. 25-40
-most bacteria are mesophiles
-most are pathogenic

thermophiles(heat-loving)

-can grow at high temp.
-good temp. for growth 50-60

Physical Requirement

2. PH

-acid/base denatures bacteria
-most bacteria grow at ph 7

Acidophile--"acid loving". Grow at low ph

Basophile--"alkaline-loving"

Physical Requirements

Osmotic Pressure

Hypertonic/Isotonic encourages growth
-plasmolysis--shrinkage of cell in hypertonic solution (bacteriostatic)

-Holophiles - "salt-loving"
bacteria can live in very salty (hypertonic) solutions

Chemical Requirements

Carbon (50%)
-backbone structure

Nitrogen(14%)
-needed for synthesis of protein to make amino acids
-Resynthesis of DNA, RNA ATP

Sulful/Phosphurus (4%)
sulfur- make amino acids
phosphorus-make phospholipids

Trace Elements
Inorganic Metallic Ions
ex. copper, zinc

Cofactors
inorganic metallic ions that attach to enzymes and make the enzymes funtion
ex. micronutrients

Oxygen
different growths

1. Obligate aerobes
growth occurs only where high levels of oxygen have diffused into media

2. Obligate Anaerobe
Growth occurs onlu where no oxygen exists

3. Facultative Anaerobes
growth is best where most oxygen is present but happens through out the entire tube although not evenly. (E.Coli)

4. Aerotolerant Anaerobe
Growth occurs evenly. Oxygen has no effect

5. Microaerophiles
Growth occurs onle where a low concentration of oxygen has diffused

Catalase
Breaks down water and gas

Peroxidase
Breakes into water

Organic Growth Factors
organic non-protein molecules
ex. vitamis

Coenzymes
organic non-protein molecules such as vitamins that attach to enzymes and make the enzyme functional (micronutrient)

Medias

Culture Medium
any nutrient substance that can support microbial growth

Requirements for a usuful media
1. Must supply physical+chemical requirements for growth
2. It must be able to be sterile
3. Must be able to be incubated

Types of Media

Chemically Defined Media
-microbiological growth medium with exact chemical composition

Complex Media
Microbiological growth medium where the exact composition is unknown (beef extract) is the most common type. it's not uniform

Selective Medium
Inhibits the growth of unwanted microorganisms but allows the growth of wanted one (salt, ph)

Differential Medial
Indicates the presence of a specific microorganism usually by color change

Enrichment Culture
media designed to make the microorganism grow into large numbers from a small amount

Reducing Medium
creates anaerobic environment by removing gaseous dissolving oxygen

Having a Pure Culture
-Deep-freezing--bacteria is suspendedin an antifreeze so ice crystals won't form

Freeze-Drying
Fast-freezing then in a vaccum the ice sublimates, turns into a gas not a liquid.
Lyophilization

Growth of Bacterial growth

Binary Fission
asexual form of reproduction in which one cell splits into two genetically identical

Generation Time
Time needed for a cell to divide, or for a population to double
20 min for e.coli

bacterial growth curve
the number of cells over time

Lag phase
occurs after inoculum is put into sterile media
-no cells are dying but many dividing
-no growth, but intense biochemical activity

Log phase
Intense cell growth
-shortest generation time
-all cells are metabolic active
-very sensitive, anything can intefere with growth

Stationary phase
-microorganism start to use up nutrients
-population levels
-# of cells forming equals the amount dying

Death Phase
nutrient has been used up
accumulation of metabolic waste has reached deadly toxic levels.
More cells are dying than being formed

Measurement of Microbial Growth

Plate Count
Viable plate count
-very accurate
-too many steps (bad)
-too much equipment(bad)
-takes at least 24hrs for results

Turbidity
not as accurate
one step procedure
no contamination
not a lot of equipment used
immediate results

end of chap 6

Terminology

Sterilization
Complete destruction or removal of all microbial life, including endospores. Absolute value

Commercial Sterilization
Sufficient heat treatment to kill sensitive endospores of clostridium botulinum
-any endospores that survive won't germinate under normal storage condition

Disinfection
the destruction of vegetative pathogen on non-living objects and surfaces (bleach)

Antiseptics
the destruction of vegetative pathogen on living tissues

Degerming
Physically removing microorganism from a limited area of the skin.
Mechanically removing by scrubbing with soap and water

Sanitization
treatment intended to lower microbial counts on eating or drinking utensils
safe to public health levels

Biocide-kill microorganism
sporocide-kill endospores
fungacide-kill fungi
verucide-kill virus
turbeculocide-kill turberculosis

Sepsis
-Decay, putrification
-presence of microoganism in normal sterile tissue
-presence of bacteria in blood multiplying

Asepsis
any procedure that prevents contamination, infection

Factors that influence the effectiveness of treatment

1. number of microorganism
the more there are, the longer it takes to kill the population

2. Environmental Influences
the presence of organic material
-weaken and even chemical agents to reduce completely the action of these methods of microbial growth

Time of exposure
15 minutes on autoclave
UV light

Microbial Characteristics
Endospores-most resistant
Gram positive-least resistant

Actions of microbial control agents
(what is damaged)

1. Alteration of membrane polarity
if damaged it looses the selective permeability

2. Damage to protein
-Denaturing
-Coagulation
-Precipitation

3. Damage to nucleic acids
can't say damage to nucleus because they don't have a nucleus

Physical Methods
1 Heat
Autoclave-steam under pressure
Pasturization

Dry Heat
Flaming-bunsen burner
incineration
complete denaturation

Hot air sterilization
170ºC-2 hrs to sterilize

2 Filtration
uses no heat
physically separates microbes from a suspending liquid or gas by passing a screen like device

3.Dessication
Drying by evaporation (bacteriostatic)
Removes water

4. Osmotic Pressure
bacteriostatic
bacteria in a hypertonic solution loosed water
Plamolysis occurs
(sun drying)

5.Radiation
physical method of microbial control
-sterile

Ionizing
short wave lenghts
fast moving
high energy
very penetrating
ionizes water to make free radicals
x-rays, gamma-rays

non-ionizing
long wavelenghts (265nm)
slow low energy particles
not penetrating
damages cellular DNA
UV light

chemical methods
--characteristic of effective desinfection

1. Concentration
2. Temperature
3. Contact with material to be disinfected
4. pH

Chemical Agents

Phenol
first accepted and used agents for aseptic surgery
-first used by Joseph Lister
-acts to denature protein
-not weakened or neutralized by organic material
-source was carbolic acid
-not used any more because of odor, irritating to skin, kills WBC, used as standard of comparison

Phenolics
Derived from phenol, chemically altered
-reduces irritating and bad properties of phenol
-retain killing properties

Bisphenols
compound derived from 2 phenolics bridged together
-disrupts all membranes
-effective on G+ and G-

Halogens
powerful oxidizer
Tincture-an aqueous solution in alcohol
Iodophore-iodine with an organic detergent

Alcohol
best degermer

Heavy Metals
-forms cations
-denature enzymes
oligodynamic action--ability of small amounts of heavy metal ions to exhibit antimicrobial activity (copper, zinc, silver)

Surface-Active Agents
-surfactants
-soaps+detergents
-lower the surface tension water
-acts as emulcifier

Quaternary Ammonium Compounds
-group of detergent derived from ammonium ions
-disrupt cell membrane of bacteria
-odorless, colorless, tasteless
-stable
-easily diluted
-non-toxic
-good for G+ not for G-

Aldehydes
Groups of liquid chemical agents
-embalming fluid
-inactivate proteins

Gaseous chemosterilizers
uses gas to sterilize
-very penetrating
-doesn't use heat
-denature protein
-sporocidal
-used to sterilize heat-sensitive equipments
-doesn't leave residue
gas used is ethaline oxide

Peroxygens and other forms of oxygens
-hydrogen peroxide
-powerful oxidizers
-free radical formers
-chemical sterilent

chapter 5

Metabolism- all the chemical reaction within a cell or organism.

Catabolism--decomposition
these are chemical reactions where larger reactants are broken down into smaller products
Chemical bods are broken

Anabolism--synthesis
those chemical reactions where smaller, simpler, less energy rich reactants come together to make a larger, more complex, more energy-rich product
Chemical bonds are made

Metabolic Pathways
Energy is transferred to ATP in a series of biochemicals
-aerobic respiration
-anaerobic respiration
-fermentation

Enzymes
-proteins
-lower activation energy
-very specific
-reusable
-have functional 3-D shape that holds them together by weak hydrogen bonds
-some are more complex
-some are just proteins

Apoenzymes
The protein portion of an enzyme

Cofactors
inorganic metabolic that binds to an enzyme to make it functional

Coenzyme
a non-protein organic molecule (vitamins) that binds to an enzyme to make it functional

Holoenzymes
the complete functional enzyme

Substrate
The substance that is catalyzed be the enzyme

Active Site
The area on an enzyme where a specific substrate will bond

Factors that influence enzyme activity

1.Temperature
good is 37C
under is bacteriostatic (inhibit growth)
Over is bacteriocidal (kills)

2.pH
good is 7
acid/base baocide

3.Substrate Concentration
if saturated becomes bacteriostatic

4. Inhibitors
Chemicals that binds to enzyme and stops activity

Generation of ATP
Oxidation--the loss of electrons from one atom or molecule
Reduction--gain of electrons by an atom or molecule

Redox Reaction
It supplies energy to make ATP
it's taken from glucose

Phosphoryalation
adding a phosphate group to a molecule

substrate level of phosphoralation
the phosphate is directly transferred from a compound to ATP

Oxidative-phosphorylation
Redox reaction

Cellular Respiration
Aerobic
the final electron acceptor(h atom) is oxygen
-water is an end product
-Most efficient
-yields 38 ATP

Anaerobic Respiration
The final electron acceptor is any inorganic molecule other than oxygen
-water can't be made
-few atp is generated

Fermentation
the final electron acceptor is an organic molecule and the final product is an energy-rich reduced compound
-least efficient
-makes only 2 ATP
-doesn't use oxygen

Metabolic Diversity

Phototrophs
organism that obtain energy from light

Chemotrophs
Organism that obtain energy from the oxidation of chemical compounds

Autotrophs
organism that obtain their carbon from inorganic CO2 gas

Heterotrophs
Organism that obtain their carbon from pre-formed organic molecule

1.Photoautotrophs
Organism obtain their energy from light and carbon from inorganic CO2 gas

Chemoautotrophs
Organism obtain theur energy and carbon from organic compound

Photoheterotrophs
A few unique bacteria that uses light as energy source and organic compunds as carbon source

Chemoautotrophs (rock eaters)
they use inorganic chemical compound as source of energy and inorganic CO2 gas as a carbon source