Download Culturing Bacteria

Bacteria
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Bacteria are the oldest, simplest, and most abundant form of life on earth.
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Their roles are varied, from decomposition, to parasite, to recycling nutrients to infection and
disease.
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They are our constant companions present in everything we eat and on everything we touch.
• Prokaryotic organism; which means they do not have a defined nucleus, so the
DNA strands float in the cell cytoplasm
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Eukaryote organism; has a defined nucleus with the DNA strand visible inside.
• Bacteria are prokaryotic organisms, to small to see with the naked eye unless
they are cultured on agar so you can see the colony.
• Colony is a large group of bacteria that has grown from one single bacteria
• Bacteria reproduce by dividing in half
• To see with microscope you must magnify a minimum of 400 times and then
still look like the head of a pin.
Bacterial Shapes
There are 3 basic shapes
• Cocci: spherical shape
• Bacilli: rod shaped
• Spirillium: twisted rods, spiral shaped
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Bacterial Arrangements
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terms are added to the shape names to label the bacteria
Staphlo: means clusters
(ex. staphylococcus)
Strepto: means chains
(ex. streptobacillus)
there are many others, these are the two most common
Grams staining
• technique to differentiate bacteria based on the structure of
their cell wall.
• Crystal Violet
• Grams Iodine
• Decolorizer
• Safranin
• The cell wall reacts with the alcohol and the lipids dissolve.
Culturing Bacteria
• Means to grow them in a petri dish, or test tube of agar or
broth.
• Reason is because need large amount of the bacteria
ENERGY REQUIREMENTS
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Bacteria have different energy requirements for life and need to take in organic compounds such
as carbon.
Autotrophs--make their own energy
Hetrotrophs-- need to consume to get energy
Photosynthetic: obtain energy by the process of photosynthesis, so they contain chlorophyll.
Chemotrophs: these exchange chemicals with other organisms to obtain energy. They have a
symbiotic relationship with another organism. (they must have another organism helping them
to obtain energy to stay alive) ex. nitrogen fixing bacteria
Chemoheterotrophs: most common form, they obtain energy by feeding on organic material and
breaking that down. (just like us)
Hand Washing Lab
#1 way to prevent the spread of Bacteria
• Locals---your normal bacteria that is on your skin, it is part of
you
• Transients---these we pickup by touching things such as door
handles, shaking hands
• In the lab what grew for most of us was our locals
• Why, washed all the transients away
Antibiotics lab
• Zone of inhibition---area where bacteria does not grow
• Antibiotic can slow down the growth of bacteria or can kill it
• Some antibiotics will have no effect, bacteria are resistant.
Antibiotic use
• Risk of over use -- create resistant strains to antibiotics
• Large concern
Virus
• Not a living organism
• Only a strand of nucleic acid
• Once inside a living cell the nucleic acid is added to the
organisms DNA and it then exhibits it traits. (cold, flu)
Viral treatment
• No way to treat a virus
• Only can treat the symptoms
• Antibiotics will not work