Microbial TERMS

Question 1

Obligate Aerobes
Obligate Anaerobes
Facultative Anaerobes

Answer 1

Obligate aerobes survive and grow with oxygen. Obligate anaerobes cannot survive in an oxygen-containing environment; the presence of oxygen leads to cell death. Facultative anaerobes can toggle between aerobic metabolism can switch to anaerobic metabolism.

Question 2

Organisms classified based on the temperature ranges they live in:

source
https://bio.libretexts.org/Courses/North_Carolina_State_University/MB352General_Microbiology_Laboratory_2021(Lee)/06%3A_Microbial_Physiology/6.02%3A_Temperature_pH_and_Osmotic_Requirements

Answer 2

Organisms are classified based on the temperature ranges they live in:

Psychrophiles: less than zero (32 F)
Psychrotrophs: 0-30°C (32 F - 86 F)
Mesophiles: middle temperatures 15-45°C
(59 - 114 F)
Thermophiles: 40-80°C (104 - 176 F)
Hyperthermophiles: above 65°C (+149 F)

Question 3

Organisms classified based on pH ranges they live in:

Source
https://bio.libretexts.org/Courses/North_Carolina_State_University/MB352General_Microbiology_Laboratory_2021(Lee)/06%3A_Microbial_Physiology/6.02%3A_Temperature_pH_and_Osmotic_Requirements

Answer 3

Hydrogen ions in a solution = pH. Organisms grow best at a specific pH range based, in part, on the environment they have evolved to live in. If bacteria are outside their optimal pH range their proteins can become denatured. Ranges of pH over which an organism can live place them in groups:

Acidophiles: below pH 5.5
Neutrophiles: pH 5.5 -8.5
Alkaliphiles: pH above 8.5

Question 4

What conditions do Halophiles live in?

Answer 4

The halophiles can live in areas of extremely high salt concentrations like salt lakes, and thalassohaline environments where seawater is evaporated.

Question 5

Halotolerant living conditions

Answer 5

Halotolerance is tolerance to ionic stress, or the ability of an organism to grow at salt concentrations higher than those required for growth. Halotolerant organisms are able to survive at high salt concentrations but do not require these conditions for growth.

Question 6

Osmophiles living condition

Answer 6

An osmophile is a microorganism adapted to environments with high osmotic pressures, such as high sugar concentrations. Osmophiles are similar to halophiles (salt-loving organisms) in that a critical aspect of both types of environment is their low water activity, aW.

Halophile organisms that live in environments with salt concentrations ranging from 15% to saturation. Osmophiles: Organisms that live in environments with a high osmotic gradient.

Question 7

Xerophiles

Answer 7

A xerophile is an extremophilic organism that can grow and reproduce in conditions with a low availability of water, also known as water activity.

Question 8

Endotoxin vs Exotoxin

Source:

https://microbiologyinfo.com/differences-between-exotoxins-and-endotoxins/

Answer 8

Endotoxins:

Usually gram negative bacteria
produces toxin when it dies
unusual to form spore

are heat stable lipopolysaccharide-protein complexes which form structural components of cell wall of Gram Negative Bacteria and liberated only on cell lysis or death of bacteria

SALVADO DEFINES: The toxin produced by a microorganism that is retained within
the cell but is liberated when the cell disintegrates (as in the intestine)
causing intoxication. Intoxication may also be produced by the ingestion
of a poisonous chemical. The toxin withstands autoclaving.

Exotoxin

usually gram positive bacteria
produces toxin during excretion
may form spore

are usually heat labile proteins secreted by certain species of bacteria which diffuse into the surrounding medium.

SALVDO DEFINES: A toxin produced by a microorganism and secreted into the sur-
rounding medium, inactivated at 142 to 176 F (61–80C).