Microbial Nutrition
   Nutrition – Is a process by which chemical 
       substances (nutrients) are acquired from the 
       environment and used in cellular activities
   Essential nutrients – Is Nutrient must be provided 
       to an organism
   Two categories of essential nutrients:
        – Macronutrients – Is nutrient required in large quantities; 
           play principal roles in cell structure and metabolism 
             • For example :Proteins, carbohydrates
        – Micronutrients or trace elements – Is nutrient required 
           in small amounts; involved in enzyme function and 
           maintenance of protein structure
             • For example :Manganese, zinc, nickel
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       Chemical Analysis of Cell Contents
     • 70% water   .,Proteins  and  96% of cell is 
        composed of 6 elements :Carbon ,Hydrogen ,Oxygen
          – Phosphorous .,Sulfur and Nitrogen
     Nutritional Types :
   Main determinants of nutritional type are:
   1-Carbon source – heterotroph, autotroph
   2-Energy source  
   Chemotroph – gain energy from chemical 
   compounds
   Phototrophs – gain energy through 
   photosynthesis                                                                      3
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         Sources of Essential Nutrients
     • According to the type of Carbon sources the 
        nutrition classify into
     • Heterotroph – must obtain carbon in an organic 
        form made by other living organisms such as 
        proteins, carbohydrates, lipids, and nucleic acids
     • Autotroph – an organism that uses CO , an 
                                                                        2
        inorganic gas as its carbon source
         –Not nutritionally dependent on other living things
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                                   Nutrients
   Nutrients classify according to their component 
                                           into
 • Organic nutrients – contain carbon and hydrogen 
     atoms and are usually the products of living things
      – For example:Methane (CH4), carbohydrates, lipids, proteins, 
         and nucleic acids
 • Inorganic nutrients – atom or molecule that contains 
     a combination of atoms other than carbon and 
     hydrogen .For example:
      – Metals and their salts (magnesium sulfate, ferric nitrate, 
         sodium phosphate), gases (oxygen, carbon dioxide) and 
         water
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        Growth Factors: Essential Organic 
                                     Nutrients
      • Growth factors :Are Organic compounds that 
          cannot be synthesized by an organism because 
          they lack the genetic and metabolic mechanisms 
          to synthesize them
      • Growth factors must be provided as a nutrient
           –For example:Essential amino acids, vitamins
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