Lecture 9 Microbial Responses Flashcards
Ideal growth conditions for a microbe
A temperature where all their enzymes are folded properly and working at the optimum rate
Plenty of food
The correct atmosphere for their own type of respiration
Available water
Environmental condition that dictate microbial growth and distribution and habitats of microbes
Temperature
pH
Osmolarity (water concentration/availability)
Oxygen
What does temperature control
Chemical and enzymatic reaction
What happens to enzymes and protein when above the maximum temperature
Denatured
What happens to the cell membrane when below the minimum temperature
May no longer function- required for nutrient transport and energy production
Psychrophiles have an optimal growth temperature of
15 degrees celcius or lower
Found in environments that are constantly cold and rapidly due at room temp
Freezing prevents microbial growth but doesn’t always cause what
Cell death
Effects of freezing
•Dehydration
•Ice crystal formation
Above 65 degrees celcius only what exists
prokaryotic life (bacteria and archaea)
Optimum growth temperature of Hyperthermophiles
> 80 degrees celcius
What is more thermophilic bacteria or archaea
Archaea
What happens to double stranded DNA at high temperature
They seperate
Name the enzymes in Hyperthermophiles that prevents double stranded DNA molecules from separating at high temperature
Reverse DNA Gyrase
Reverse DNA Gyrase is absent in organism that grow below what temperature
80 degrees
What does pH refer to
concentration of hydrogen ions (H+) in a solution and is commonly expressed in terms of the pH scale, which is a log scale.
Low pH corresponds to
high hydrogen ion concentration
High pH corresponds to
low hydrogen ion concentration.
What is the formula for calculating pH
pH = -log [H+]
Most microorganisms grow best at what pH
6-8(Neutrophiles)
Acidophiles are ___ loving
Acid loving
Alkali phones are _____ loving
Alkaline loving
Internal cell pH must be close to what type of pH
Neural between a pH of 5-9
What happens to cell macromolecules(enzymes , proteins and nucleic acid) at pH extreme
They are destroyed
What is osmosis controlled in cells by which membrane
Cytoplasmic membrane
Define osmosis
the diffusion of water from high water concentration (low solute concentration) to low water concentration (high solute concentration.
Halophiles are _____ loving
NaCl loving
Osmophiles can grow in high ____ concentration
Sugar concentrations
What is commonly used as preservative to inhibit microbial growth
•salt
•sugar
How do microbes grow under condition of low water availability
High NaCl
Low H2O availability
- increase internal solute concentration
Compatible solutes are highly _____ soluble
Water soluble
Microserophiles
Grow at reduced O2 concentrations
Anaerobes
Cannot use oxygen for respiration
Facultative anaerobes
Can grow in presence or absence of oxygen
Some Gram positive bacteria can form _____ which provide protection from adverse conditions
Spores
What is the spore in bacteria surrounded by
peptidoglycan-rich cortex layer and a keratin-like spore coat.
Spores are resistant to
•Heat
•Drying,
•Radiation,
•Freezing,
•Toxic chemicals
•Antibiotics &
•Can be difficult to eradicate with standard disinfectants.
Spores are involved in the transmission of what diseases
anthrax, caused by Bacillus anthracis
tetanus, caused by Clostridium tetani;
botulism, caused by Clostridium botulinum
*gas gangrene, caused by Clostridium perfringens
Treatment for B.anthracis- Anthrax
•Penicillin
•Ciprofloxacin
Anthrax symptoms
High fever
Massive swelling
Death
Coagulase-negative staphylococci form
biofilms or slime on implanted biomaterials and catheters
Biofilms form when bacteria adhere to
surfaces and excrete
slimy glue-like substances which anchor the cells
What are Biofilm resistant to
Antimicrobial agents
