Environmental Influences & Control of Microbial Growth Flashcards
Microbes have both the fastest and the slowest growth rates of any known organisms, HOT-SPRING BACTERIAS can double in ____ ____, while DEEP-SEA-SEDIMENT microbes may take _____ ______.
10 minutes
100 years
What determines the growth rate of organisms?
Nutritions and niche-specific parameters (temperature + pH).
What are “NORMAL” growth conditions?
What are organisms that are not habited within these conditions called?
Sea level
0.9% salt + ample nutrients
Temperature: 20-40C
pH = neutral
EXTREMOPHILES
(T/F) The “normal” conditions on Earth when life began were extreme. Therefore, the earliest microbes grew in these extreme environments.
True!
What allows us to study the biology of organisms that we can not culture?
BIOINFORMATIC ANALYSIS
Match the following Microbes to their appropriate environmental niche:
Regarding Temperature:
1) Hyperthermophile
2) Thermophile
3) Mesophile
4) Psychrophile
A) Found in cold environments
B) Above 80C
C) Between 50-80C
D) Midrange temperature; most commonly studies
Regarding pH:
1) Alkaliphile
2) Neutralophile
3) Acidophile
A) Between pH 5-8 (most pathogens)
B) pH 0-5 (most chemoautotrophs)
C) Above pH 9 (in soda lakes, commercial use)
Regarding Temperature:
1) Hyperthermophile - Above 80C
2) Thermophile - Between 50-80C
3) Mesophile - Midrange temperature; most commonly studies
4) Psychrophile - found in cold environments
Regarding pH:
1) Alkaliphile - Above pH 9 (soda lakes, commercial use)
2) Neutralophile - Between pH 5-8 (most pathogens)
3) Acidophile - pH 0-5 (most chemoautotrophs)
Match the following Microbes to their appropriate environmental niche:
Regarding Osmolarity:
1) Halophile
2) Halotolerant
A) Able to grow up to 2M NaCl (best at seawater)
B) Require high salt (over 2M NaCl)
Regarding Oxygen:
1) Strict aerobe
2) Facultative microbe
3) Microaerophile
4) Strict anaerobe
5) Aerotolerant anaerobes
A) small amounts of oxygen
B) only in oxygen
C) only without oxygen
D) can grow in oxygen but only do fermentation
E) with or without oxgygen
Regarding Pressure:
1) Barophiles/Piezophiles
2) Barotolerant
3) Barosensitive
A) can tolerate high pressure but do not need (1-50 MPa mostly)
B) organisms die as pressure increases (humans)
C) adapted to very high pressure
Regarding Osmolarity
1) Halophile: require high salt (over 2M NaCl)
2) Halotolerant: able to grow up to 2M NaCl (best at seawater)
Regarding Oxygen
1) Strict aerobe: only in oxygen
2) Facultative microbe: with or without oxygen (can do fermentation/respiration)
3) Microaerophile: small amounts of oxygen
4) Strict anaerobe: only without oxygen
5) Aerotolerant anaerobes: can grow in oxygen but only do fermentation
Regarding Pressure
1) Barophiles/piezophiles: adapted to very high pressure
2) Barotolerant: can tolerate high pressure but do not need (1-50 MPa mostly)
3) Barosensitive: organisms die as pressure increases (humans)
What are cardinal temperatures?
The minimum, optimum and maximum temperatures at which an organism grows.
*range is typically <40C
*temperature also changes GAS and MINERAL concentration in water
Match the following terms regarding cardinal temperatures to their definitions:
1) Minimum
2) Between minimum - optimum
3) Optimum
4) Maximum
A) Enzymatic reactions occurring at increasingly rapid rates
B) MEMBRANE GELLING; transport processes so slow that growth is very minimum
C) Protein denaturation; collapse of the cytoplasmic membrane; THERMAL LYSIS
D) Enzymatic reactions occurring at maximal possible rates
1) Minimum: MEMBRANE GELLING; transport processes so slow that growth can NOT occur
2) Between minimum - optimum: Enzymatic reactions occurring at increasingly rapid rates
3) Optimum: Enzymatic reactions occurring at maximal possible rates
4) Maximum: Protein denaturation; collapse of the cytoplasmic membrane; THERMAL LYSIS
What are the molecular adaptations to life in the cold?
1) Production of ENZYMES that function optimally in the cold
2) Different composition of the CYTOPLASMIC MEMBRANES
3) COLD SHOCK PROTEINS (chaperones)
4) CRYOPROTECTANTS prevent formation of ice crystals
5) EXOPOLYSACCHARIDE cell surface slime
As a molecular adaptation to the cold, there are productions of enzymes that function optimally in the cold. Fill in the blanks regarding enzymes in cold:
There are _____ α helix than the β-sheets, this provides greater _______ for catalysis at cold temperatures.
There are ____ POLAR and ____ HYDROPHOBIC amino acids.
There are _______ weak bonds.
More; Flexibility
More; Less
Fewer
What type of fatty acids are prevalent in cytoplasmic membranes at low temperature?
UNSATURATED + SHORTER-CHAIN fatty acids
*and some polyunsaturated fatty acids, which remain flexible at very low temperatures
How do PROTEINS STABILIZE in high temperatures?
1) A few amino acid substitutions make HEAT-TOLERANT ALPHA-HELICAL FOLDS
2) Core is more HYDROPHOBIC, preventing protein unfolding in an ionic environment
3) More IONIC BONDS on protein SURFACE between basic and acidic amino acids, preventing protein unfolding
4) PRODUCTION OF SOLUTES
5) CHAPERONES (Heat shock proteins)
How do bacterial and archaeal MEMBRANE STABILIZE in high temperatures?
1) Bacteria have lots of SATURATED - LONG CHAIN fatty acids
2) Archaea have LIPID MONOLAYERS
How does DNA STABILIZE in high temperatures?
1) High solute concentration of K or compatible organic compounds, prevents DEPURINATION, DEPYRIMIDIZATION and protects against osmotic stress
2) High solute concentration of PUTRESCINE or SPERMIDINE (also stabilizes ribosomes)
3) REVESE DNA GYRASE (topoisomerase) in archaea
4) HIGHLY BASIC (POSITIVE CHARGE) DNA BINDING PROTEIN in archaea to avoid unfolding by strong winding of DNA around nucleosomes
How does RIBOSOMAL RNA STABILIZE in high temperatures?
GREATER PROPORTION OF GC NUCLEOTIDE BASE PAIRS (higher H-bonds than AU bonds)
*not the case for DNA, maybe rRNA is more fragile or less protected?
In high temperatures, the membrane is contains more of _____-_____, ______ fatty acids.
In cold temperatures, the membrane is contains more of _____-_____, ______ fatty acids.
High temperatures: LONG-CHAIN, SATURATED
Low temperatures: SHORT-CHAIN, UNSATURATED
(T/F) In temperatures ranging 15-50C, there is rapid growth of bacteria. In colder temps, the growth is slow. In hotter temps, microbes are destroyed.
True!
