Micobiology Unit 2

Chapter 6

What are the right circumstances for microbe growth?

Temperatures, energy source, carbon source, access to O2/CO2, pH ,Osmotic pressure, and Barometric pressure

Temperature Microbes

Psychrophiles, Psychrotrophs, mesophiles, thermophiles, hyperthermophiles

Psychrophiles

Likes the cold; 0-15 degrees celsius.

Real-life application: Listeria, fatal

Psychrotrophs

15-25 degrees celsius

Real-Life application: Hansen Disease (Mycobacterium Leprae)

Mesophiles

25-45 Degrees celsius, Easiest to identify because we can provide the environment.

Real-Life Application: Human excrements

Thermophiles

45-75 degree celsius, 8 degrees higher than human temp.

Real-Life Application: Fever, body raises heat to fight bacteria

Hyperthermophiles

70-110 degrees Celsius, Typically archaea

Real-Life Application: Geysers spew water hotter than water boiling point

Right Energy Source

Phototrophs, Chemotrophs

Phototrophs

Gets energy from the Sun, ADP - ATP

Example: Plants

Chemophiles

Gets energy from the energy that was already there (Organotrophs and Lithotrophs)

Example: Humans

Organotrophs & Lithotrophs

Organotrophs: Chemical bonds in organic compound. (Organic Compounds: Carbon + Hydrogen)

Lithotrophs: Non organic chemical bonds

Carbon Source

CO2 Autotrophs & Organic Carbon

CO2 Autotrophs

“Self feeding” Carbons from the air

Example: Plants

Organic Carbon

Carbon-Hydrogen Bonds, Heterotrophs

Example: Humans

O2/CO2

Obligate Anaerobe, Facultative Anaerobe, MIcroaerophiles, Obligate Aerobes, Capnophiles

Obligate Anaerobe

Does not use/cannot be in the presence of O2

Example: Bacteroides Fragilis; Lives in the large intestines

Facultative Anaerobe

uses O2 if available, but can survive without it

Example: E. Coli

MIcroaerophiles

Requires O2 but in low concentrations

Obligate Aerobes

Cannot survive without O2

Examples: Humans, Mycobacterium Tuberculosis

Capnophiles

Need high CO2 levels

pH

Acidophiles, Neutrophiles, Alkaliphiles

Acidophiles

Reproduces a pH level less than 5

Neutrophiles

Reproduces at pH 7

Alkaliphiles

Reproduces at pH greater than 9

Osmotic Pressure

Osmosis: Movement of water through the membrane

Low osmotic & High osmotic

Low Osmotic Pressure

Water will move into a cell, causing the cell to swell and burst

High Osmotic Pressure

Water will move out, shrivel up and die

Barometric Pressue

Barophiles, Hyperbaric chamber

Barophiles

Likes pressure that is heavier than normal atmospheric pressure

Hyperbaric Chamber

Forces pressure on certain areas

Bacteria Growth equation

Nt=No x 2^n

Agar Plates

made by seaweed as a surface for bacteria growth

Nutrient Agar

Contains essential nutrients for bacteria to eat

Example: Beef extract

Complex Medium

Nutrients added but not in any precise amount or combination

Chemically Defined Medium

Bacteria want the certain things left out/added.

Example: Mannitol Salt Agar

Selective Medium

Favor growth of some microbes, inhibit growth of others

Example: McConkey Agar; bile salt+crystal violet

Differential Medium

Allows us to differentiate between microbes

Example: Sheeps blood agar