Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
44 Cards in this Set
- Front
- Back
Microbial growth
|
increase in number of cells, not cell size
|
|
culture
|
To grow or a population of bacterial cells
|
|
Three Physical requirements for Microbial growth
|
temperature
pH osmotic pressure |
|
five categories based on temperature range of growth
|
Each bacterium within a category has a Minimum temperature of growth, Optimum temperature of growth and a Maximum temperature of growth
|
|
MESOPHILES
|
Pathogenic bacteria
Optimal : 37ºC (98.6ºF) ex: Escherichia coli Streptococcus pneumoniae |
|
Danger zone
|
Cold foods minimum 40ºF (5ºC)
Hot foods minimum 140ºF (60ºC) |
|
pH (most bacteria)
|
Most bacteria grow between pH 6.8 and 7.2
|
|
Acidophiles
|
grow in acidic environments
ex: Lactobacillus, Streptococcus |
|
Molds and yeasts (pH)
|
grow between pH 5 and 6
Rhizopus Aspergillus Penicillium Saccharomycetes |
|
Osmotic Pressure
|
Hypertonic environments, increase salt or sugar, cause plasmolysis
(cheese, ham, jelly, jam, fruit preserves) |
|
obligate halophiles
|
require high osmotic pressure or die - Great Salt Lake (30%)
|
|
facultative halophiles
|
tolerate high (salt or sugar) osmotic pressure but don't require it.
|
|
Macro elements:
|
carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus
|
|
Trace elements (cofactors)
|
Inorganic elements required in small amounts usually as enzyme
ex: magnesium, zinc, colbolt |
|
Oxygen Gas:
|
O2 electron acceptor for aerobic growth
anaerobic growth requires H2, Fe, S as electron acceptor |
|
Organic growth factors:
|
metabolically deficient organism
organic compounds cannot synthesize (vitamins, amino acids, purines, pyrimidines) obtained from the medium |
|
fastidious
|
microbes that require organic growth factors
|
|
Hydrogen
|
Structural function in organic molecule and energy source
Source is any organic molecule (ex: glucose) H is energy source for chemosynthetic bacteria (Sunlight is energy source for photosynthetic bacteria) |
|
Oxygen
|
Structural function in organic molecule
Source is any organic molecule |
|
Nitrogen
|
Structural function in amino acids, proteins
Most bacteria decompose proteins as source of N |
|
Sulfur
|
Structural function in amino acids: ex: methionine
Most bacteria decompose proteins as source Some bacteria use SO42 or H2S (inorganic) |
|
Phoshorus
|
Structural function in DNA, RNA, ATP, and membranes
PO43 is a source of phosphorus |
|
obligate aerobes
|
Require Oxygen
aerobic |
|
Facultative anaerobes
|
aerobic
and anaerobic |
|
Obligate anaerobes
|
anaerobic
Killed by Oxygen |
|
Aerotolerant anaerobes
|
anaerobic
Not killed by Oxygen but it doesn't grow |
|
Microaerophiles
|
Little air lovers (15% Oxygen)
|
|
Chemically Defined Media:
|
exact chemical composition is known
qualitative, quantitative |
|
Complex Media
|
qualitative but not quantitative
extracts and digests of yeasts, meat, or plants Nutrient broth Nutrient agar |
|
Culture Medium
|
Nutrients prepared for microbial growth (i.e. nutrient broth, mannitol salts)
|
|
Sterile:
|
no living microbes
|
|
Inoculum:
|
Introduction of microbes into medium
|
|
Culture:
|
Microbes growing in/on culture medium
|
|
Agar:
|
Complex polysaccharide
Used as solidifying agent for culture media in Petri plates, slants, and deeps Generally not metabolized by microbes Liquefies at 100°C Solidifies ~40°C |
|
Anaerobic Culture Methods
|
Use reducing media
contain chemicals that combine O2 (thioglycollate or oxyrase) plus grow in Anaerobic jar |
|
Capnophiles
|
require high CO2
CO2-packet Neisseria gonorrhoeae is a capnophile |
|
Selective Media
|
suppress unwanted microbes and encourage desired microbes
|
|
Differential Media :
|
visual distinction between types of microorganisms
|
|
Mannitol Salts
Selective: |
high salt concentration selects for growth of Staphylococcus
|
|
Mannitol Salts
Differential: |
differentiates between pathogenic and non pathogenic yellow pathogenic; red non pathogenic
|
|
Differential:
|
Differentiates between
Escherichia coli ferments lactose (pink) Salmonella (non fermenter appears colorless) |
|
pure culture
|
A contains only one species or strain
|
|
Binary fission:
|
asexual process
|
|
Phases of growth
|
|