Microbial Growth Flashcards
The FIVE Is to be followed to purify and charcterize the organism
Inoculate
Incubate
Isolate
Inspect
Identify
What is an example of a medium
include liquids solids, or live organism (in the case of a Virus)
Innoculation
Place sample on sterile medium (nutrients to grown but they are the only organism present)
Using sterile loop
Incubate
Proper environment for growth (temp, pH, gas (i.e. increase/decrease amount of O2))
Isolation
Result of inoculation and incubation
Further isolate culture by “subculturing” it to obtain pure cultures
If mixture is present, choose only the colony you want
Inspection
Observing macro/microscopic characteristics
Colony shape, sizes colour, stain characteristics (gram, acid fast)
Identification
Several approaches
Morphological characteristics (cell wall, cell shapeetc.)
Useful for identifying eukaryotes
Differential staining
Gram staining, acid fast staining
Biochemical tests
Determine presence of bacterial enzymes
Immonoligical tests
Using antibodies with colours to see if they react with specific bacteria for identification
5 chemical requirements for bacterial growth
Carbon
Nitrogen
Sulfur
Phosphorus
Oxygen
Why is carbon required for bacteria
Autotrophs: Use CO2 as carbon source and inorganic salts and N source (Plants and some bacteria)
Heterotrophs: Use organic carbon sources (animals, most bacteria)
Carbon compounds are source of energy
Why do bacteria require nitrogen
Used to make amino acids and proteins
What do bacteria use phosphorus for
Used in DNA, RNA, ATP, and membranes (Source is inorganic phosphate)
What does bacteria use sulfur for
Used in amino acids, vitamins
What is the main requirement for oxygen in microorganisms?
cellular respirations
Thioglycolate broth
has an attraction for O2. Binds with O2 and generates an O2 gradient
Least O2 at the bottom of a test tube, most at the top)
Without thioglycate broth, o2 distribution would be more or less uniform
Obligate Aerobe.
Organisms that need O2: Only grow near the surface when mixed with Thioglycolate broth
Obtain energy by respiration
Produce SOD and catalse
Micrococcus and corynebacterium (skin)
Pseudomonas aeruginosa (burn infection)
Bordetella pertussis (whooping cough)
Mycobacterium tuberculosis (Lung-disease tuberculosis)
Strict/obligate Anerobe.
Organisms to which O2 is toxic. Regions without O2 contain most/all of the growth in Thioglycolate broth
Do not produce either SOD Or Catalase
Mostly carry out fermentation
Clostidium (tetani, botulinum, difficile)
Bacteroides (normal intestinal flora) - associated with APPENDICITIS
Facultative Aenerobe
Organisms that PREFER O2. Most growth near top, but growth is also spread thinly throughout the tube when in Thioglycolate broth
Produce SOD and catalse
Can carry out respiration (+O2) and fermentation (without O2)
Ex.
E. coli, Salmonella, and shigella
Staphylococcus
Saccharaomyces
Aerotolerant Anaerobe.
Organisms that ignore O2. Uniform growth, unaffected by presence of O2.
Do not require O2, and unaffected by it
Produce SOD and SOME produce catalase
Ex.
Lactobacillus and streptococcus
Sugars - lactic acid baceria
Lactobacillus
Important in women healhtm agriculture food industry
Streptococcus
Streptoccusccus pyogenes: Sore throat, scarlet fever, tonsillitis
Microaerophile.
Require less O2. Prefer to have SOME O2, but not the level that is present in air.
Require higher Co2 and lower O2 concentrations of air
Produce SOD and Catalse (Lower amounts)
Ex.
Neisseria (pathogenic/non pathogenic)
Neiseria gonorrhea (STD)
Neisseria meningitis
Free radicals
Unstable, reactive electrons released from Oxygen. damage cells cause cancer.
Antioxidants
Contain chemicals that quickly react with free radicals before they start damaging body cells
Superoxcide radical - converted to Hydrogen peroxide by superoxide dismutase (SOD) (enzyme)
Enzyme produces cataalysts that converts hydrogen peroxide to water and oxyge
Peroxidase
Enzyme that works on hydrogen peroxide to convert it to water (Normalluy present in plants)
Free radicals are commonly the product of
ETC
Botulism normally from
CANNED food
Temperature requirements for bacteria
Psychorphiles -10, 15C (Optimal) to 20 C
Psychotrophs 0C, 25C (Opt) to 30C
Mesophiles 15C (20-40C) to 45 C
Most common in humans
Thermophiles 45C (55-70C) to 80C
Hyperthemophjils 65C, (85-95C) to 105C
Which category of temperature sensitive microbes affect food preservation
Psychotrophs: Food spoilage of refrigerated foods
Mesophiles: Most common type of microbes; common cause food spoilage and diseases
Categories of microorganisms based on pH
Acidophiles
Optimum: pH 0 - pH 5.5
Neutrophiles
Optimum: pH 5.5-8
Alkalophiles
Optimum pH 8.5-11.5
Helicobacter pylori
lives in stomach under mucous layer, produces ammonia to neutralize the acid of the stomach
Damages mucous layer resulting in ulcers
Can lead to cancer
Categories of microorganism based on affinity to salt
Halophiles (salt): Love high salt concentrations
Non-halophiles: Prefer lower salt concentration
Facultative halophiles: Prefer low salt environment, but CAN grow in high salt concentrations
Extreme/obligate halophiles: REQUIRE high salt concentrations
Sterile
No living microbes
Inoculum
: Microbes introduced into the medium
Agar
Complex polysachharide
Used as solidifying agent for culture media in petri plates, slants, and deeps
Generally not metabolized by microbes
Liquifies at 100 degrees C
Solidifies at around 40 degrees C
Chemically defined (synthetic) media
All components known and quantified (AKA minimum media)
Bacteria is provided with everything it needs exactly
Complex/non synthetic media
Some components are not known o quantified
I.e. nutrient agar or nutrient broth
Don’t know EXACT composition, but you know that it is providing the bacteria with what it needs
Functional Types of Media
Enriched media: Add some nutrients that favior growth of select bacteria (i.e. add blood, agar or choclate )
To vbe added when bacteria are resistant to growth as an extra motivating factor
Differential: Distinguishes bacteria growing
One process that tells the bacteria apart
Selective: Encourages growth of some bacteria while suppressing growth of unwanted bacteria (Something is added to prevent the growth of something)
Biosafety levels
Biosafetly level 1 (Low individual and community risk)
Microorganisms that handle in a basic microbiology teaching lab
Non pathogenic E. coli
BSL 2 (Moderate individual risk, low community risk)
Microorganism that present a moderate risk of infection, operators sould wear gloves, lab coats etc.
C. diff, MRSA, Salmonella
BSL3 (High individual risk, low to moderate community risk)
Microorganisms are highly infectious airborne pathogens
Lab to be NEGATIVELY pressurized and equipped with air filters to prevent release of pathogens
Mycobacterium tb, SARS coronavirus
Not anyone can come in
BSL4 (High individual risk, high community risk)
Microorganism are highly infectious airborne pathogen
No known cure
Ebola virus, Lassa virus, smallpox
Bacterial growth implies
Increase in number of cells, not cell size
One cell becomes colony of millions
Bacteria divide via binary fission
Alternatively divide by budding, condiospores, or fragmentation
Generation
the time it takes for one cell to divide
can also be defined as the length of time required for a population to double
Standard growth curve
Lag phase: Making new enzyumes in response to new medium
Log phase (exponential growth): Most sensitive to drugs and radiation during this period
Stationary phase: Nutrients becoming limiting or waste products becoming toxic; death rate = division rate
Death phase: Death rate exceeds division
Yeast would replicate but not produce alcohol in an environment that
Contained oxygen
At what stage are bacteria more vulnerable to penecillin
Log stage
The main source of nutrients in nutrient agar to grow bacteria is
peptone and beef extract
The reaction that is carried out by the enzyme catalase produces
H2O and O2
How long does it take for the daughter cells to initiate or start the next round of replication?
No time is required – they are ready to divide immediately after DNA replication and separation of the daughter cells is complete if conditions are right.
Put the steps of bacterial replication in the correct order, starting from a parent cell.
Chromosome replication
Cell elongation
Septum formation
Separation of daughter cells
Why is there a log stage post innoculation?
The bacteria must adjust to the nutrient content in the new medium, synthesizing necessary amino acids, growth factors, and enzymes.
Why do cells enter the stationary phase
The cells are likely running out of nutrients.
The number of cells that are dying is balanced by the number of new cells that are being formed.
Harmful waste products may be accumulating.
How does a chemostat prolong the log stage of exponential bacterial growth
Chemostats provide a continued source of fresh nutrients and remove wastes and dead bacterial cells.
The most appropriate strategy for gathering data with which to plot of a bacterial growth curve.
Plate count
What results when a single bacterium reproduces
Two genetically identical daughter cells
Does the nuclear envolope disapear during cell division?
no
What enables the copied chromosomes to separate during binary fission?
The chromosomes are attached to different parts of cell membrane, which elongates and thus separates the chromosomes.
The ability of microbes to utilize N2 as a nitrogen source is called
Nitrogen fixation
Instead of oxygen, __________ may utilize nitrate or sulfate as their final electron acceptors.
obligate anaerobes
