10-Microbiology_Soil_Feb28

Nodules 25 nodule formaaon step 1 recogniaon and

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: S) –  nitrogen fixaAon. 19 Brock Biology of Microorganisms, 13th EdiAon. Nitrogen fixaAon •  Only certain prokaryotes can fix nitrogen (N2); a lot of energy is required because of the triple bond (N≡N). •  Nitrogen fixaAon is one of the most important microbial processes on earth. In the absence of ferAlizers, other organisms are dependent on nitrogen fixers. •  Some nitrogen fixers are free- living (ex.: Cyanobacteria) and others are symbioAc (ex.: Rhizobium). 20 Brock Biology of Microorganisms, 13th EdiAon. Nitrogen fixaAon •  ReacAon is catalyzed by nitrogenase complex (metal cofactors) •  8 electrons are required, 2 are lost as H2 in the process. •  •  Ammonia is the final product and is used to produce amino acids, etc. Dinitrogenase reductase is inhibited by the presence of oxygen. 21 Brock Biology of Microorganisms, 13th EdiAon. Free- living Nitrogen fixers •  Azotobacter, Beijerinckia and Clostridium. •  Widespread in soil, require a soil rich in organic maber to provide energy for nitrogen fixaAon. •  Produce ammonia that can be used by plants (NH3, dissolves in water to produce ammonium NH4). •  Clostridium: strict anaerobe. •  Azotobacter: strict aerobe. The enzyme is protected by a very high rate of O2 consumpAon, which keeps the intracellular e...
View Full Document

This note was uploaded on 03/20/2014 for the course PSYC 101 taught by Professor Catone during the Spring '07 term at CSU Fullerton.

Ask a homework question - tutors are online