1. Nutritional Strategies and Nutrient Acquisition
Nutritional Strategies (Types)
Required Resources
Nutritional Types
Nutrition Acquisition
Passive transport
Active transport
“Scavenging”

2. Resources for All Life:
Energy: cells need to do the work of membrane transport, biosynthesis, and mechanical processes.
Electrons: anabolic reactions (biosynthesis) require reducing power (adding e-).
Major Elements (macronutrients): Carbon, Nitrogen, Phosphorous in varying proportions (e.g. C:N:P ratio of eukaryote algae ≈ 106:16:1; bacteria ≈ 100:25:1; fungi ≈ 400:20:1). These, along with O, H and S, are all supplied in organic or inorganic form. In lesser amounts are Fe, Mg, Ca, K, and Na, which are mostly supplied as inorganic forms.
Trace Elements (micronutrients): Mn, Zn, Co, Cu, Mo, & Ni.
Growth Factors: essential amino acids, vitamins, and nucleoside bases are needed for growth but cannot be made by many organisms; some are sources of macro- and micro- nutrients

4. Major Nutritional Types: (see Table 5.2) Energy → Electrons → Carbon
Photolithoautotrophy
Photoorganoheterotrophy
Chemolithoautotrophy
Chemoorganoheterotrophy

5. Transport Types: Passive Diffusion Facilitated Diffusion
Both follow a concentration gradient, high to low; therefore reversible.
Passively through membrane lipids or porins; rate increase linear.
Facilitated by selective transporters; rate increase with [S] then plateaus at “saturation”.
Transport Types: Passive Diffusion Facilitated Diffusion

6. Transport Types: Primary Active Transport
Against concentration gradient requires energy.
“Primary” transporters directly use ATP for energy.
May require solute binding proteins to scavenge solute.
Transport Types: Primary Active Transport
ATP-Binding Cassette Transporter (ABC transporter)

7. Transport Types: Secondary Active Transport
Solute transport against a concentration gradient.
Secondary transporter couples solute with a flow of protons or other ions along strong concentration gradients; energy source.
Mechanism may be antiport or symport.

8. Transport Types: Group Translocation
Solute can transport against concentration gradient.
Solute is modified during transport and energy released.
Often a high energy P-group gets translocated in a cascading sequence toward a lower energy state.
e.g. phosphoenolpyruvate (PEP): sugar phosphotransferase system (PTS).
PST is involved in chemotaxis.

9. “Send out the scavengers!” Siderophores
Iron bioavailability is low; “rust never sleeps”.
Bacteria release these scavenger molecules to facilitate iron transport.
Multiple siderophores complex an iron molecule.
Siderophores can be species specific.