Lab Exercise 7: Physical Requirements for Bacterial Growth

Osmosis

The movement of water down its concentration gradient across a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration.

Solutes

The substances dissolved in water that impact its concentration

High; low

In osmosis water moves from ________ water concentration to ___________ water concentration

Low; High

In osmosis water moves from _________ solute concentration to ____________ solute concentration

Osmotic pressure

The pressure that would have to be applied to a solution to prevent osmotic flow of water.

Isotonic

When the solute concentration inside and outside of the cell are equal.

Hypertonic

When the solution concentration is greater outside the cell than inside the cell the solution is considered ________

Isotonic

Most of the bacteria will need _____________ conditions to survive.

Plasmolysis

When bacterial cells shrink and pull away from the cell wall due to the loss of water.

Halophiles

Microorganisms that require or are adapted to conditions where their cells are under high osmotic pressure due to high concentration of salt

Weak Halophiles

Microorganisms that grow optimally in 1-3% salt.

Moderate Halophiles

Microorganisms that grow optimally in 1-3% salt.

Extreme Halophiles

Microorganisms that grow optimally in 15-20% salt.

Nonhalophiles

Organisms that require the osmotic pressure to be low or close to isotonic

Halotolerant

Organisms that are able to survive in high salt conditions but do not require these conditions to grow

Halophiles

Extreme __________ will not grow in conditions where salt concentrations are low.

Psychrophiles

Microorganisms that grow at temperatures at temperatures between 0 and 15 degrees Celsius.

Mesophiles

Organisms that can grow between 0 and 50 degrees Celsius, but optimum usually between 20-40 degrees celsius.

20-40

What is the optimum growth range for mesophiles?

Thermophiles

Microorganisms that require temperatures above 45 degrees Celsius and optimum 45-80 degrees Celsius.

Aerobes

Microbes that grow in the presence of air or require oxygen for growth

Anaerobes

Microbes that grow without oxygen or require oxygen free conditions to live.

Facultative Anaerobes

Microorganisms that can grow in both the presence and absence of oxygen.

Microaerophilic

When microorganisms require slightly less than atmospheric levels of oxygen.

Capnophilic

Organisms that require high levels of carbon dioxide for optimum growth

Aerotolerant Anaerobes

Organisms that can withstand low levels of oxygen but do not need it to metabolize

Strict (obligate) anaerobes

Organisms that cannot survive oxygen exposure.

Psychrophiles

Microorganisms that prefer temperatures between 0 and 15 degrees Celsius

Mesophiles

Microorganisms that prefer temperatures between 20 and 40 degrees Celsius

Thermophiles

Microorganisms that prefer temperatures between 45 and 80 degrees Celsius

Hyperthermophiles

Microorganisms that prefer temperatures between 80 and 100 degrees Celsius

Permanently

Bacteria that are exposed to too high of heat will be disabled ___________ due to denaturation.

Temporarily

Bacteria exposed to too cold of temperatures will be disabled _________ until the heat is raised back to an optimal range.

Capnophiles

Microorganisms that like higher than normal atmospheric levels of carbon dioxide.

1%

What percent of a normal atmosphere is made of carbon dioxide?

Halophile

If there was growth only in the high concentrations of salt then we know that the microorganism was a _______

Halotolerant

If there was gradually less growth as salt concentrations rose then the organism was ________

Nonhalophile

If there was no growth when there was salt than we know the organism was a ___________ (halo sensitive)

Nonhalophile

Escherichia coli did not grow in any of the salt concentrations. What kind of microbe is it?

Nonhalophile

Pseudomonas aeruginosa did not grow in any of the salt concentrations. What kind of microbe is it?

halotolerant

Bacillus subtilis grew in 5% and 10% NaCl but not 15% or 20%. What kind of microbe is it?

Halotolerant

Staphylococcus aureus grew in 5%, 10% and 15% NaCl but not 20%. What kind of microbe is it?

Halotolerant

Staphylococcus epidermidis grew in 5%, 10% and 15% NaCl but not 20%. What kind of microbe is it?

Normal Flora

S. aureus and S. epidermidis are both part of the ________ ____________ therefore being halotolerant helps them to survive salty surfaces like our skin.

Turbid

In the tubes that were _________growth occurred.

Mesophiles

Most of the bacteria that we studied were __________ meaning that they grew at 22 degrees and 35 degrees but were inhibited at 4 degrees and 55 degrees.

Mesophile

Bacillus subtilis grew at 22 degrees and 35 degrees but was inhibited at 4 degrees and 55 degrees. What type of bacteria would this be?

Mesophile

Escherichia coli grew at 22 degrees and 35 degrees but was inhibited at 4 degrees and 55 degrees. What type of bacteria would this be?

Mesophile

Pseudomonas aeruginosa grew at 22 degrees and 35 degrees but was inhibited at 4 degrees and 55 degrees. What type of bacteria would this be?

Mesophile

Staphylococcus aureus grew at 22 degrees and 35 degrees but was inhibited at 4 degrees and 55 degrees. What type of bacteria would this be?

Geobacillus stearothermophilus

What bacteria that we studied was able to grow at 55 degrees Celsius?

Geobacillus stearothermophilus

Which bacteria that we studied was a thermophile?

55 degrees Celsius

Geobacillus stearothermophilus grew at which temperature(s)?

At the top of the tube only

If an organism is an aerobe where will you see growth in the thioglycolate tube?

In the bottom of the tube

If an organism is an anaerobe where will you see growth in the thioglycolate tube?

Throughout the tube

If an organism is a facultative anaerobe where will you see growth in the thioglycolate tube?

Middle layer

If an organism is a microaerophile where will you see growth in the thioglycolate tube?

Aerobe

Bacillus subtilis grew in the top of the thioglycolate tube. Which type of bacteria is it?

Aerobe

Pseudomonas aeruginosa grew in the top of the thioglycolate tube. Which type of bacteria is it?

Facultative Anaerobe

Escherichia coli grew throughout the thioglycolate tube. Which type of bacteria is it?

Microaerophile

Staphylococcus aureus grew towards the middle/top layers of the thioglycolate tube. Which type of bacteria is it?

Anaerobe

Clostridium sporogenes only grew in the bottom of the thioglycolate tube. Which type of bacteria is it?