LAB 3: Aseptic technique & bacterial cell morphology

Sterile

absence of any/all viable organisms; includes viruses

does not have to mean KILLED

can also mean organisms have been moved

NOTE: just because something looks sterile does not mean it actually is!!

Pure Culture

only ONE type of organism growing

Mixed culture

two or more organisms growing, purposefully

Contaminated culture

unwanted microbes present

Turbid

visible cloudiness (millions of cells at this point)

What happens when a single bacterial cell is deposited on the surface of nutritive medium?

The single bacterial cell will start to divide exponentially.

colony

thousands (up to billions) of cells are formed, this is a visible mass.

Why is it important to identify and categorize isolated bacterial colonies based on their appearance and morphology?

It allows distinction of species in a mixed culture and enables transfer of a single colony to sterile media for cultivating pure cultures.

What does colony morphology depend on?

It depends on the media. 

What are some colony shapes and size that are often used?

circular and irregular

What are some colony shapes and sizes that are not often used in our Lab?

filamentous, rhizoid, spindle, punctiform (tiny)

What are the different colony sizes?

punctiform

small

moderate

large

What are the different colony margin?

entire - smooth

undulate (wavelike)

lobate/erose

What are the kinds of colony elevation?

flat and raised

What are some terms for colony elevation?

effuse: very thin, spreading, flat,

umbonate: raised, raised with spreading edge convex

What does colonial shape refer to?

refers to the overall shape of the colony

What does colonial margin refer to?

It refers to the edge of the colony

What does elevation refer to?

refers to the way the colony rises above the agar,

What happens when something is water soluble?

The isolation spreads, not clear

What happens when the organism is water insoluble?

Localized to colony only, isolation is much better

Coencentric

swaeming

Mucoid

really really, snooty gooey

What is streaking used for?

a technique used in microbiology for isolation of bacteria

What is agar?

A substance extracted from cell walls of red algae. It is commonly used to grow bacteriological cultures, agar must be impregnanted with nutrients such as beef extract and peptone in order to support life

Why is agar slants good?

The slanting of the surface of the agar gives the bacteria a greater surface area on which to grow in a test tube. They are also useful in maintaining bacterial cultures, more so than stacks of petri dishes.

What bacterial species did we use in lab?

serratia marcesens and micrococcus luteus

What agar plate did we use?

TSA plate

What are the steps to streaking?

1. grab a loopful of the bacteria, DO NOT GRAB MORE BACTERIA AFTER THIS!

2. spread the bacteria on one side like ¼ of the way

3. then turn the plate 45 degree and do the same streaking motion

4. repeat steps 2 and 3, two more times

5. on the last streak you will streak like normal and then draw a swiggle towards teh middle.