Transcript Transfer of Bacteria: Aseptic Technique

Bell Ringer
• The arrow in the figure is pointing to what?
• A proteins __________ structure is seen below.
Objective
• Use appropriate microbiology media, test
systems, and lab equipment.
• By the end of the lesson students will
– Perform an aseptic transfer of sterile broth media
from one test tube to another
– Obtain pure colonies by performing a T-streak
– Complete pre-lab questions on the handout
• 5 points for no contamination
• 5 points for pure colony
• 12 points Worksheet
Transfer of Bacteria: Aseptic
Technique
Background
• Inoculate: bacteria are introduced into culture
media
– This must be accomplished without
contamination, or introducing unwanted mos into
the media
• Aseptic technique: To transfer microbes from
one place to another without contamination
of the culture, the sterile medium, or the
surroundings
Background
• All culture media is sterilized or rendered free
of all living organisms before use
– Therefore, containers of media, test tubes, and
Petri dishes should not be opened until ready for
use
Types of Media
• Broth cultures: liquid media used to provide
large quantities of bacteria room to grow
– Fast growing conditions, easy to transport
• Agar slants: test tubes containing solid culture
media that were left at an angle when
solidifying
– Provide a solid growth surface
– Easy to transport and store
– What is used to solidify media?
Types of Media
• Agar Plates (petri dishes): Solid culture media
used to determine the colony morphology of a
organism
– Create pure cultures
Aseptic Technique
• Inoculating loop
– Transferring instrument of cultured bacteria
– Sterilize before and after use
– Made of metal
Bacterial Cultures
• Pure culture – a culture with a single species
of cells
• Colony – a cluster of cells originating form the
multiplication of a single cell
• Subculture – the transfer of a microorganism
from the original culture to a new one
Streak Plate for Isolation
• Spreading of organisms on a plate such that
individual cells become separated and grow
into individual colonies
• This method can yield a pure colony
– One specie
• Isolation is commonly performed when you
want to identify an organism
– An individual species can be separated out from
the mixed culture
Streak Plate for Isolation
 Bacteria is streaked across the surface of the
medium
 During streaking, cell density decreases
 Individual cells will be deposited on the agar
 These individual cells will grow into colonies or
colony forming units (CFU)
Streak Plate for Isolation
• T-streak method
– Flame loop in-between
– Incubate plates upside-down… Why?
Label All Tubes and/or Plates
• Name
• Date
• Sample
– Bacteria that is in the tube/plate
Practice
• Complete Worksheet