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

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

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

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

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)

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.

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.

“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.