VMC 211: General Veterinary Microbiology (1+1)

BACTERIAL NUTRITION

Nutrional requirements

• All organisms require a source of energy. Those dependent on chemical compounds for energy are called chemotrophs. Those which use radiant energy are called phototrophs. Both types are present in bacteria.
• All organisms require a source of electrons. Based on the source of electrons bacteria can be grouped as
  • Lithotrophs which use reduced inorganic compounds as electron donors. Chemolithotrophs and photolithotrophs.
  • Organotrophs use organic compounds as electron donors. Chemoorganotrophs and photoorganotrophs.
• All organisms require carbon in some form for synthesis of cell components. Based on the source of carbon bacteria can be grouped as
  • Autotrophs use CO2 as major or even sole carbon source.
  • Heterotrophs require organic compounds as their carbon source.

	Energy source	Carbon source	H/ electrons
Photoautotrophs (photo lithotrophic autotrophs)	Light	CO2	Inorganic
Photoheterotrophs (photo organotrophic heterotrophs)	Light	Organic compound	Organic
Chemoautotrophs (chemolithotropic autotropha)	Chemical energy Source (inorganic)	CO2	Inorganic
Chemohetrotrophs (chemo organotropic heterotrophs)	Chemical energy source (organic)	Organic compounds	Organic