Biological N2 fixation by cyanobacteria from the Antarctic Peninsula in a continuous monitoring system of nitrogenase under adverse environmental conditions

• Grant number: 12/19036-2
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: February 01, 2013
• End date: January 31, 2014
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Marli de Fátima Fiore
• Grantee: Diego Bonaldo Genuário
• Supervisor: Lucas J. Stal
• Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Institution abroad: Royal Netherlands Institute for Sea Research, Netherlands
• Associated to the scholarship: 10/00321-3 - Diversity and functional activity of cyanobacteria isolated from South Shetlands Archipelago, Antarctic Continent, BP.DR

Abstract

This plan proposed research is to investigate the ecological role of cyanobacteria as contributors to the input of nitrogen in the Antarctic environment. The overall objective is to study the biological nitrogen fixation in cyanobacterial strains isolated from King George and Deception Islands, Antarctica, under controlled conditions of light, temperature and oxygen levels, simulating environmental parameters experienced by these strains in Antarctica and in a scenario global warming. To date, 65 cyanobacterial strains were isolated from substrates collected as a result of the PhD project entitled "Diversity and functional activity of cyanobacteria Archipelago South Shetlands, Antarctic Continent" (FAPESP Process n. º 2010/00321-3 ). Of these, 53 cyanobacterial strains were tested for PCR amplification of fragments of the nifH, involved in the encoding of the nitrogenase enzyme complex related to the biological nitrogen fixation. Of these, 35 strains showed positive amplification and gene fragment that had sequenced successfully. Among these, 24 strains belong to the heterocystous group (Nostocaceae family) known nitrogen fixers, eight strains belong to the homocystous group and three strains are unicellular. The presence of this gene fragment in the non-heterocystous and unicellular forms indicates the genetic potential to perform biological nitrogen fixation (BNF), however, their ability fixative only be proven after testing acetylene reduction under conditions of low oxygen concentration,since these morphotypes did not exhibit spatial separation between cells that perform photosynthesis and FBN. Low temperatures and large amplitude of light intensity - extreme conditions and characteristics of the Antarctic - are investigated in strains that showed the nifH seen that might influence the activity of the nitrogenase enzyme complex and consequently rates FBN. Also explored will be the effect of increased temperature on the rates of activity of nitrogenase complex strains mentioned in simulating the response of these BNF microorganisms in a global warming scenario. (AU)