Association with an ammonium-excreting bacterium allows diazotrophic culture of oil-rich eukaryotic microalgae

ORTIZ MARQUEZ JC; DO NASCIMENTO M; DUBLAN M DE LOS A; CURATTI L

APPLIED AND ENVIRONMENTAL MICROBIOLOGY

AMER SOC MICROBIOLOGY

Lugar: Washington; Año: 2012 vol. 78 p. 2345 - 2352

0099-2240

Concerns on depletion of the world’s reserves of oil and global climate change have promoted during the last years an intensification of research and development towards the production of biofuels and other alternative sources of energy. There is currently much interest in developing the technology for third generation biofuels from microlgae biomass mainly because of its potential of high yield and reduced land use change in comparison with biofuels derived from plant feedstocks. Regardless the nature of the feedstock, the use of fertilizers, especially nitrogen, entails a potential economic and environmental drawback for the sustainability of biofuels production. In this work we have studied the possibility of nitrogen biofertilization by diazotrophic bacteria applied to the culture microalgae as a promising feedstock for next generation biofuels. We have obtained an Azotobacter vinelandii mutant strain that accumulates several times more ammonium in the culture medium than the wild type cells .Ammonium excreted by the mutant cells is bioavailable to promote growth of non-diazotrophic microalgae. Moreover, this synthetic symbiosis was able to produce oil-rich microalgae biomass using both carbon and nitrogen from the air. This work provides proof-of-concept that artificial symbiosis may be considered as an alternative strategy for low-N-intensive cultivation of microalgae for sustainable production of next generation biofuels and other bioproducts.