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What is the purpose of incubating the unopened plates?

To use as a contol group. They will not change so one would have enough to control to study off of.

If growth appears on the unopened plates what probably happend?

it was contaminated between the autoclave and time of incubation.

Why were the specific types of exposure chosen for this exercise?

To procide bateria for the growth and produce a reaction for the exercise

Why were you asked to incubate the blates at two different temperatures?

They will likely be affected differently at different temperatures depending on how the bateria feeds of the media

What is growth media?

nutrients that allow bateria to be isolated and cultured

Why do microbiologists need growth media?

to classify bateria as a prokaryote (no nucleus) we need to give the bacteria what it likes to eat.

What are the requirements of growth media?

-carbon, oxygen, nitrogen, hydrogen

What are the categories of media?

physical states
chemical composition

categories of media: physical states

solid, can be solidified
solid, cannot be solidified

categories of media: chemical composition

Defined: synthetic, know the componets
Complex: non-synthetic, dont know exact porportions

Growth means in micro:

^ in population no size

Slant tube provides

more surface area in more confined space


organic and inorganic compounds in an exact chemical formula

complex/ non-synthetic

at least 1 ingredient that is not chemically definable.

enriched media

complex organic substances such as blood, serum, hemoglobin, or special growth factors required by fastidious microbes

General Purpose

grows a broad range of usually non-synthetic microbes

6 types of culture media


An exapmple of selective media

same sample but change the Ph one will grow bateria and one will grow fungus.


loves blood


ehh it's okay blood


no blood

most commonly used media (4)

-nutrient broth
-trypticase soy broth agar
-nurtient agar
-brain and heart infusion broth agar

Nutrient Broth

-Liquid beef extract and peptone

Trypticase soy broth or agar

-beef soy extract

Nutrient Agar

-Solid beef extract, peptone, agar

Brain and Heart infusion broth agar

-Beef, heart, brain extract


-Polysacharide from red algae


-The theory of being everywhere.

The 5 I's of Culturing Microbes



growing bateria to study


Colony forming unit

Pure culture

culture composed of cells arising from a single progenitor (CFU)


-Temp controlled chamber
-microbe multiplies and produces macroscopically observeable growth


-If one bacterial cell is separated and has space on nutrient surface it will grow a colony.


-Thick Leg Like shape


-looks like filliments sticking out from middle


-oval shape


-Shallow curves around the bateria


-long curves around the bacteria


-lots of circular motions around the bacteria


-leg like extentions from middle


-slightly higher than just convex


- looks like a boob with a nipple

mixed culture

-2 or more species

contaminated culture

-unwanted microbes


-without contamination

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