Lab 1: Factors Affecting Microbial Growth Flashcards
what do bacteria need to grow?
-H2O
-C
-Energy
-Nitrogen
-Minerals
-Growth Factors
describe growth factors
-organic molecules
-organisms can NOT make them on their own
-for growth or enzymatic reactions
define photoautotrophs
use CO2 as their C source and solar energy to make ATP
define chemoautotrophs
carbohydrates, proteins, lipids are used as C source and to make ATP
most bacteria are
chemoheterotrophs
bacteria are…
ubiquitous
how do you sterilize culture media?
by autoclaving
what is the temperature and pressure that autoclaves operates at?
121 degrees Celsius
15 psi
types of culture media
-broth
-plate
-slant
agar is…
a polysaccharide extracted from algae used to thicken culture media
list the 5 types of agar plates and broths
- chemically defined
- complex
- enrichment
- selective
- differential
what types of agar plates and broths will be used in this lab?
complex
describe a chemical culture media
-exact chemical composition known
-minimal amount of nutrients needed for survival
-synthetic
describe a complex culture media…
-exact composition is NOT known
-made from meat and soybean extract
describe a enrichment culture media…
-has extra growth factors to support the organisms with special nutritional needs
give an example of an extra growth factor that can be added to a TSA plate
sheep’s blood
describe a selective culture media…
-has special chemicals that stimulate growth of some bacteria while inhibiting the growth of others
give an example of selective medium that can be added to a TSA plate
adding an antibiotic that allows only resistant bacteria to grow
describe a differential culture media…
-has pH indicators; allows for different organisms to be distinguished by changing color
what are the 3 different classifications of bacteria?
- morphological
- cultural
- physiological
define morphological characteristics
shape of individual bacteria cells, arrangement, and size
-require a microscope to be viewed
define cultural characteristics
form, color. and size of colonies on plates and the pattern of growth in broths
define physiological characteristics
biochemical (metabolic) reactions carried out by the organism
-requires both selective and differential media
define hemolysis
an enzyme secreted by some bacteria that breaks open RBCs
hemolysis is observed on a ____ and has a ___ __ ____ around the colonies
BAP
zone of clearing
when you can observe and classify the appearance of bacterial colonies, you are observing _______ characteristics.
cultural
