week 3: microbial culture and nutrition Flashcards
macronutrients g/L (CHONPS)
Carbon, oxygen, hydrogen
part of major biological molecules (carbohydrates, proteins, lipids, nucleic acids)
Nitrogen:
part of proteins and nucleic acids
Phosphorus:
part of nucleic acids, phospholipids
Sulfur:
Present in some amino acids (proteins)
How do microbes obtain C and N?
Microbes can obtain C from
1. Organic sources (heterotrophs)
2. From CO2 (autotrophs)
Microbes can obtain N from
1. Ammonium or organic nitrogen compounds (ex: proteins)
2. A few types of bacteria produce an enzymes called nitrogenase that converts nitrogen gas to ammonium (diazotrophs)
macronutrients (inorganic) CIMPS
Metal ions- calcium, iron, magnesium, potassium, sodium
Required in some enzymes (enzymes cofactors), electron carriers, membrane stability
micronutrients
Metal ions: iron, cobalt, manganese, molybdenum, zinc, copper, nickel, chromium, selenium, tungsten
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bioremediation
Use of living organisms (usually microorganisms) to clean up waste
- Crude oil
○ Mixture of hydrocarbons
○ Water insoluble (hydrophobic)
○ Lack other macronutrients
Many components of crude oil are toxic to higher organisms like humans, but microorganisms in natural environment use hydrocarbons from crude oil as a carbon source for growth
culturing bacteria in the lab, how do they have different nutrient requirements?
Different bacteria have different nutrient requirements due to differences in
- Metabolic capabilities and metabolic pathways
○ Ex: autotrophs vs heterotrophs - Ability to transport the nutrients into the cell
Types of media to grow microorganisms in the laboratory:
- Liquid vs solid media
- Defined versus complex versus enriched media
- General purpose vs selective vs differential vs enrichment media
what are defined media?
defined: Precise chemical composition is known, you can calculate the concentration of each element
general purpose media
Useful for many different heterotrophs
May contain extracts and digests of animals, plants, or yeasts organic matter
selective media
Selects growth of organisms with a particular trait, suppresses growth of others
differential media
Allows visualization of physiological trait (difference in colour)
Usually contains some kind of dye of pH
enrichment media
○ Used to increase the concentration of one microbe over others, therefore enriching a sample for the microorganism of interest
○ Generally a liquid media
○ Includes specific nutrients/compounds to promote growth of particular bacteria
○ Rarely contains inhibitory compounds to prevent growth of certain organisms
Encourage growth of some microorganism suppress growth of others, increasing the concentration of particular microbes in this medium
ingredients commonly found in complex media
○ Peptone: digests of animal tissues (contains amino acids and peptides)
○ Tryptone: enzymatic digest of casein (milk protein) (contains peptides
○Soytone: enzymatic digest of soy (contains proteins and high concentrations of vitamins and carbohydrates
○ Yeast extract: cell contents of yeasts (contains amino acids, peptides, and vitamins)
○ Beef extract: dried extract of beef (contains amino acids and peptides)
complex media
contains macro and micronutrients but exact composition of each element is unknown
enriched media
for cultivating “fastidious” heterotrophs, bacteria and archaea with complex/unknown growth factor requirements
Contains additional nutrients (ex: blood, serum) to support wide variety of bacteria (non-specific)
what type of media is mackonkey agar and the ingredients and their properties
- A selective and differential media
○ Crystal violet: kills gram positive bacteria
○ Bile salts: allow only bacteria that grows in the intestine to survive
○ pH indicator: bacteria that ferments lactose form red colonies
○ Lactose
○ Peptone
○ Agar: to solidify the media
