4.4

Extremophiles

Microorganisms that live in harsh environments. Ex. archaea

Optimum growth temperature

Temperature that the organism grows most rapidly. Usually closer to upper limit of range.

Psychrophiles

Grow in cold arctic and antarctic regions in lakes w glaciers. Optimum between

Psychrotrophs

Grow better at lower temps

Mesophiles

Most common bacteria in this group. Pathogens are closer to 35 while bacteria that go in soil are closer to 30

Thermophiles

Optimum between. Live in hot springs and compost heaps

Hypothermophiles

Usually archaea. Highest recorddd is 122°C

Why can some microbes stand high temps

Because their proteins are not killed at high temps. Their proteins depend on the amino acid sequence which controls the number and position of the bonds that form in the protein which determine its three dimensional structure.

Food preservation

Fridge temps slow spoilage (4C) which limit the growth of mesophiles. Psychrophiles and psychotrophs can still grow but will spoil food slower. Only preserves not kill.

Aerobic environment

O2 is there

Anaerobic environment

No O2

How to find out of microorganisms needs oxygen

SHAKE TUBE! Melt liquid agar, let cool, add microbes, let agar harden. Oxygen will be high at the top and low at the bottom. Microbes will grow only at the oxygen level that’s right for them.

Obligate aerobes

Oxygen is a must. They use it for energy harvesting and Atp generating pathways.

Facultative anaerobes

Grow better with O2 but can still grow without it. They use aerobic respiration if there is O2 but use different metabolism if not. Grows faster w O2 because it produces the most APT. ex ecoli.

Obligate anaerobes.

Cannot multiple if there’s O2, it can even kill them. Harvest energy using other methods. ex clostridium botulinum.

Microaerophiles

Only need small amounts of O2.

Aerotolerant anaerobes

Neutral. They can grow with O2 but don’t use it to harvest energy. Called obligate fermenters because fermenting is their only metabolic option.

Neutrophiles

Most microbes are neutrophiles. Cannot live in highly acidic conditions. Some bacteria found a way by decreasing the acidity of the environment around it.

Acidophiles

Optimum ph below 5.5. Some have an optimum ph less than 1

Alkaliphiles

Optimum above 8.5. Live in alkaline lakes and soils.

Plasmolysis

If water available but too concentrated, water will diffuse out which causes the cytoplasm to dehydrate and shrink from the cell wall.

Halotolerant

Organism that can grow in high salt concentrations. Up to 10% NaCl

Halophile

Need high levels of salt to grow. Up to 3% NaCl. Some archaea require 9%