Lecture 10 - Microbial Growth Flashcards
List examples of macronutrients.
- carbon
- nitrogen
- phosphorus
- iron
- sulfur
Why do cells require carbon?
- cells are 50% carbon on a dry weight basis
- C is needed to form nucleic acids, proteins, sugars, and lipids
- form organic compounds used by heterotrophs (e.g. glucose, benzoate )
- autotrophs use CO2
Why do cells require nitrogen?
- cells are 12% nitrogen on a dry weight basis
- required for amino acids, nucleotides
- typically sources for inorganic growth NH4Cl
- N2 fixing bacteria can use nitrogen gas as an N source
Why do cells require phosphorus?
- required for nucleic acids phospholipids
Why do cells require sulfur?
- needed for in amino acids cystine and methionine
What macronutrients are required for certain enzymes?
- potassium
- magnesium
- calcium
- sodium
Why do cells need iron?
- vital for: 1) cellular respiration, 2.) cytochromes, 3.) iron sulfur proteins
- cells can produce siderophores (iron-binding agents or iron chelators) to bind environmental iron and transport it into the cell
Why is PTDC useful for groundwater remediation?
strain KC secretes the molecule PDTC (believed to be an iron chelator) –> PDTC also transforms CT
produced by pseudomas stutzeri KC:
- a motile, denitrifying, gram negative rod shaped bacteria
- isolated by Craig Criddle
- rapidly transforms carbon tetrachloride (CT) a ground water contaminant
- CT is transported to CO2 and other inert compounds without creating chloroform
What are micronutrients?
metals and often other “trace metals”
are important for various enzymes
e.g. Cu, Ni, Cr, Se, Zn, etc.
What are growth factors?
organic compounds required in small amounts
e.g. vitamins, amino acids, bases
–> only required for some bacteria
Describe a chemically defined media.
contains a precise amount of purified chemicals added to water
e.g. Yang’s paper
Describe a complex (undefined media).
contains a digest of animal or plant products
easy to prepare, highly nutritious
e.g. LBmedia (Luria Berafani)
Describe selective media.
contains chemicals that selectively inhibit the growth of some microorganisms but not others
e.g. growth of antibiotic resistant bacteria in media with antibiotics
Describe differential media.
contains an indicator (dye) allowing for the differentiation of particular chemical reactions that occur during growth
–> growth of target bacteria will change color (because of pH change)
Describe binary fission.
More prokaryotes replicate through this process.
Involves the separation of a single cell into two identical daughter cells, each containing one copy of the parental DNA.
