microbial growth pt2 Flashcards
name 2 energy generating systems
- autotrophs - light or oxidation of INORGANIC compounds
- heterotrophs - organic compounds oxidation
important elements of microbial growth
- carbon
-hydrogen - oxygen
- nitrogen
- sulfur
- phosphorus
carbon sources for microbes
- glucose
- maltose
- sucrose
- starch
- cellulose
nitrogen sources for microbes (organic and inorganic)
- organic - amino acids
- inorganic sources - NH4+
NO3-
NO2-
N2
what is a culture media used for?
to grow bacteria
what is the media for culture media?
liquid and solid
- liquid - broth
- solid - agar
where does agar come from?
agarose - found in cell walls of certain species of red algae
what are spread plates used for?
- counting microorganisms in a liquid sample
- sampling an environmental surface
what is a selective media?
- type of media designed to - inhibit growth of unwanted organisms- allowing growth of specific ones
what is differential medium?
- media containing reagents that permit —visual differentiation of desired bacteria —
types of agar
- mannitol salt agar
- eosin methylene blue
- MacConkey agar
what is the function of mannitol salt agar?
used to differentiate staphylococcus species based on “mannitol fermentation”
what indicates a positive fermentation result on MSA?
- yellow halos around bacterial growth
(this shows that acids has been produced)
what does eosin methylene blue differentiate?
- lactose fermenters from non fermenters among gram- negative bacteria
what makes macConkey agar selective and differential?
contains bite salts
- crystal violet to inhibit gram positive bacteria
and neutral red to indicate lactose fermentation
what colour do e-coli colonies appear on EMB agar?
- green metallic sheen due to strong acid productions
