Lecture 7: Bacterial Nutrition Flashcards
Autotrophy
don’t need organic carbon for energy or structural carbon
phototrophy
light
lithotrophy
inorganic non-carbonaceous material for energy
heterotrophy
use reduced organic carbon
- parasite/pathogen
- saprophyte
What are the major nutrients?
- carbon
- nitrogen
- sulfur
- phosphorus
Carbon
About 50% of cell mass is carbon
- Either derived from inorganic or organic sources
Nitrogen
Some bacteria fix nitrogen directly from the
atmosphere
Some use ammonia or organic nitrogen from
digested macromolecules
Nitrogen makes up about 15% of cell “dry weight”
Sulfur and phosphorus
Between them, sulfur and phosphorus make up
about 4% of cell dry weight
Essential in protein, DNA structure, ATP
Organic trace elements
Essential in synthesis of cofactors such as FAD, NAD, CoA
Examples of inorganic trace elements
magnesium, molybdenum, iron, copper, and zinc
- These are required for growth, but are usually present in tap water in sufficient quantities
What functions require certain inorganic trace elements?
many enzymatic functions
- These are required for growth, but are usually present in tap water in sufficient quantities
Oxygen
present in many, many forms
Water, Carbon Dioxide, Oxygen Gas
Reactive forms such as peroxide, hydroxyl radicals
molecular oxygen is…
an essential nutrient for some organisms, a deadly
poison for others
Bacterial use enzymes to detoxify various reactive oxygen forms-hydrogen peroxide, free radicals
Superoxide dismutase, Catalase
How do obligate aerobes respond to oxygen?
cannot grow well in the absence of oxygen
How do facultative anaerobes respond to oxygen?
grow using fermentation pathways in the absence of O2
How do microaerophiles respond to oxygen?
grow only in the presence of small concentrations of molecular oxygen