culture
cultivation of microorganisms
medium
a nutrient-containing environment in which microbes can multiply
inoculation
introduction of microbes into media for culture
sterile
free of microbes
incubation
20-40 degrees
control of atmospheric gases
microbial growth in liquid medium shows up as:
cloudiness, sediment, scum, color
microbial growth on solid medium shows up as:
colonies
media is classified according to 3 properties:
-physical state
-chemical composition
-functional type (purpose)
media classified by physical state are divided into what 4 categories?
-liquid
-semisolid
-solid (can be liquified)
-solid (cannot be liquified)
media classified by chemical composition is divided into what 2 categories?
-chemically defined (synthetic)
-complex
media classified by functional type is divided into what 8 categories?
-general purpose
-enriched
-selective
-differential
-anaerobic growth
-specimen transport
-assay
-enumeration
liquid media
-broths
-milks
-infusions
Semisolid
-clot-like consistency at room temperature
Semisolid media is used to:
determine the motility of bacteria
Semisolid media contains enough gelatin or agar to:
thicken, but not produce a firm surface
solid media provides a firm surface upon which cells can form:
discrete colonies
Solid media is used to:
isolate bacteria and fungi
Agar is a complex ______ isolated from the red alga ______.
polysaccharide, Gelidium
Agar is ____ at room temperature, liquefies at ___ degrees Celcius, and once liquefied, does not begin to solidify again until it reaches ___ degrees Celcius.
solid, 100, 42
Defined (synthetic) media
media whose chemical compositions are precisely chemically defined
Complex media (undefined)
-contains at least one component that is not chemically definable
-examples: blood, serum, meat extracts or infusions, milk
general purpose media
complex media that contains a mixture of ingredients that support a wide variety of microbial life
Enriched media
-contains complex organic substances that fastidious bacteria require for growth
Enriched media contain ______ ______, which are specific vitamins or amino acids.
growth factors
selective media
contains one or more agents that inhibit the growth of certain microbes (a "select" microbe)
Selective media is important in ______ _______ of a certain type of microorganism from a _____ sample.
primary isolation; mixed
Differential Media
Allow multiple types of microorganisms to grow, but display visible differences between colonies
Blood agar
used as an enrichment medium for fastidious microbes as well as differential media
Hemolysins
enzymes that lyse red blood cells to release iron-rich hemoglobin
Beta hemolysis
complete lysis of red blood cells
Alpha hemolysis
incomplete lysis of red blood cells
Gamma hemolysis
no hemolysis
Which media can be both selective and differential?
-MacConkey Agar
-Mannitol Salt Agar
Reducing media
grow anaerobic bacteria
Carbohydrate fermentation media
contains sugars and pH indicators to show fermentation
Transport media
maintains and preserves specimens
Assay media
used to test the effectiveness of antimicrobial drugs
Enumeration media
used in industrial and environmental microbiology
Colony
a discrete mound of cells formed on solid nutrient surface
Requirements of Isolation
-small number of cells inoculated into a relatively large volume or expansive area of media selected to encourage growth
-relatively firm surface
-petri dish
-inoculating tools such as an inoculating loop
Streak plate method
-small droplet of culture is spread across the surface of a medium with an inoculating loop
-gradually thins out the sample and separates the cells in order to encourage the growth of discrete colonies
Loop Dilution or Pour Plate Method
-sample diluted into cooled liquid agar
-Inoculated tubes poured onto petri dishes to harden
-diluted cells have space to grow
-some colonies may grow deep in the medium rather than just on the surface
Spread Plate Technique
-small sample pipetted onto surface of the plate
-"hockey stick" used to spread sample evenly on surface to form individual colonies
anexic
free of other living things except for the one being studied
subculture
a second-level culture from a well-isolated colony
mixed culture
container that holds 2 or more identified, easily differentiated species of microorganisms
contaminated culture
culture which contains unwanted microbes of uncertain identity
Biochemical tests can determine chemical characteristics such as:
-nutrient requirements
-products given off during growth
-presence of enzymes
-mechanisms for deriving energy
Microbial profiles are determined through combining:
-phenotypic testing
-genotypic testing
-immunologic testing
-macroscopic analysis
-microscopic analysis
American Type Culture Collection (ATCC)
-maintains the largest stock of live cultures for study and experimentation
-freeze dried fungal, bacterial, viral, and algal cultures
Biohazardous material:
-cultures and specimens collected from patients or the environment
-must use Steam Sterilizing or incineration to destroy microorganisms
What is Steam Sterilization also called?
autoclaving