1Copyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.1Chapter 5Microbial NutritionCopyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.2The Common Nutrient Requirements• macroelements (macronutrients)– C, O, H, N, S, P, K, Ca, Mg, and Fe– required in relatively large amounts• micronutrients (trace elements)– Mn, Zn, Co, Mo, Ni, and Cu– required in trace amounts– often supplied in water or in media componentsCopyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.3Requirements for Carbon, Hydrogen, and Oxygen• often satisfied together– carbon source often provides H, O and electrons• autotrophs– use carbon dioxide as their sole or principal carbon source• heterotrophs– use organic molecules as carbon sources2Copyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.4Nutritional Types of MicroorganismsCopyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.5mixotrophy•chemical energy source (inorganic)•inorganic H/e-donor•organic carbon sourceCopyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.6Requirements for Nitrogen, Phosphorus, and Sulfur• needed for synthesis of important molecules (e.g., amino acids, nucleic acids)• nitrogen supplied in numerous ways• phosphorus usually supplied as inorganic phosphate• sulfur usually supplied as sulfate via assimilatory sulfate reduction3Copyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.7Sources of nitrogen• organic molecules• ammonia• nitrate via assimilatory nitrate reduction• nitrogen gas via nitrogen fixationCopyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.8Growth Factors• organic compounds• essential cell components (or their precursors) that the cell cannot synthesize• must be supplied by environment if cell is to survive and reproduceCopyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.9Classes of growth factors• amino acids– needed for protein synthesis• purines and pyrimidines– needed for nucleic acid synthesis• vitamins– function as enzyme cofactors4Copyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.10Copyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.11Practical importance of growth factors• development of quantitative growth-response assays for measuring concentrations of growth factors in a preparation• industrial production of growth factors by microorganisms Copyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.12Uptake of Nutrients by the Cell• Some nutrients enter by passive diffusion• Most nutrients enter by:– facilitated diffusion– active transport– group translocation5Copyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.13Passive Diffusion• molecules move from region of higher concentration to one of lower concentration because of random thermal agitation• H2O, O2and CO2often move across membranes this wayCopyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.14Facilitated Diffusion• similar to passive diffusion– movement of molecules is not energy dependent– direction of movement is from high concentration to low concentration– size of concentration gradient impacts rate of uptakeCopyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.15Facilitated diffusion…• differs from passive diffusion – uses carrier molecules (permeases)– smaller concentration gradient is required for significant uptake of molecules– effectively transports glycerol, sugars, and amino acids• more prominent in eucaryotic cells than in procaryotic cells6Copyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.16Figure 5.1•rate of facilitateddiffusion increasesmore rapidly andat a lowerconcentration•diffusion ratereaches a plateau when carrier becomessaturatedcarrier saturationeffectCopyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.17Figure 5.2note conformational changeof carrierCopyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.18Active Transport• energy-dependent process– ATP or proton motive force used• moves molecules against the gradient• concentrates molecules inside cell• involves carrier proteins (permeases)– carrier saturation effect is observed7Copyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.19ABC transporters• ATP-binding cassette transporters• observed in bacteria, archaea, and eucaryotesFigure 5.3Copyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.20Figure 5.4antiportsymportCopyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.21Group Translocation• molecules are modified as they are transported across the membrane• energy-dependent processFigure 5.58Copyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.22Iron Uptake• ferric iron is very insoluble so uptake is difficult• microorganisms use siderophores to aid uptake• siderophore complexes with ferric ion• complex is then transported into cellFigure 5.6Copyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.23Culture Media• preparations devised to support the growth (reproduction) of microorganisms• can be liquid or solid– solid media are usually solidified with agar• important to study of microorganismsCopyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.24Synthetic or Defined Media• all components and their concentrations are known9Copyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.25Complex Media• contain some ingredients of unknown composition and/or concentrationCopyright © McGraw-Hill companies, Inc. Permission required for reproduction or display.26Some media components• peptones– protein hydrolysates prepared by partial digestion of various protein sources• extracts– aqueous extracts, usually of beef or yeast• agar– sulfated polysaccharide