NUTRIENT NITROGEN DYNAMICS, ROLE OF TERMITES

TERMITES AND NITROGEN DYNAMICS

New discoveries have resulted in a revolution of assumptions on nitrogen fixation.   Unlike the carbon cycle, the nitrogen cycle can’t be measured globally using satellite data.  It has been impossible to forecast nutrient dynamics in face of human disturbances.  We humans increasingly dominate nitrogen input throughout the world.Climate changes and human disturbances change the nitrogen dynamics, thus changing bacterial activity and composition

TERMITES GIVE CLUE INTO RECYCLING NITROGEN

Termites can digest a great deal of dead wood.  They are major pesta that  destroy man made structures.  Their talents are sought by humans to process biofuels.  Since wood is an unbalanced foodstuff and lacks nitrogen, there is no simple solution.

Termites are successful because of symbiotic microorganism that complements their metabolism.  Hongoh found the genome of a bacterial living within a protozoa that lives in termite guts.  The bacteria fixes atmospheric nitrogen, allowing it to recycle nitrogen from waste nitrogen products of its host protozoa.  It can then make amino acids for its own use and also for the protozoan host.  There is a lot of energy needed and the bacteria gets it not just from the hydrogen produced during nitrogen fixation but also from the anaerobic fermentation of sugars released from cellulose in the protozoan.                Source Science Nov 14,2008

NEW FINDINGS

Ammonia oxidation by microbes was thought to need oxygen to occur.  Is seems bacteria can oxidize ammonium without oxygen using NITRITE instead.  The nitrite acts as the electron acceptor that results in N2 gas production.

 Finding an ammox organism helps explain the deviations between marine nitrogen cycles and observed ammonia concentrations and N2 production in anaerobic marine environments.

Archaea was thought to be present only in extreme environments make up a large part of marine plankton worldwide.  Some can even make ammonia.  They also contribute to nitrification in marine and terrestrial environments.

New lineages have been found for nitrogen fixation.  Trichodesmium, which forms floating colonies, was thought to be major nitrogen fixer in the open ocean.  This is not the case.  Unicellular cyanobacteria, Crocosphera, are as important a nitrogen fixer.  It is found in hot springs along with archea.

There is a critical gap in our knowledge between microbial composition and nutrient flux.  All microbes in a functional group are neither necessarily functional nor redundant.  Our nitrogen dynamics are constantly being altered and change our microbial composition and their activity.

  Sources: Science May 9, 2008, Science Nov 14, 2008

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