Influence of C/N ratio in growth of cyanobacteria Geitlerinema sp. from sugarcane vinasse

Abstract. Vinasse is the main wastewater of ethanol distillation-fermentation. From the biochemical point of view, this wastewater can be regarded as a nutrient broth because of composition in organic molecules and salts. Despite of this, few studies about the use of this wastewater as substrate medium for the growth of microorganisms. Some strains of cyanobacteria, as Geitlerinema sp., are capable of heterotrophic growth, a property that permits the application of wastewater treatment for organic matter and nutrients removal. In this context, the present research aiming evaluate to influence of C/N ratio in the biomass production by Geitlerinema sp. from vinasse. Results indicate that is feasible the heterotrophic cultivation of this filamentous cyanobacterium from vinasse with a wide range of C/N ratio. The highest biomass productivities were obtained for C/N ratio 5 and 40, although the condition more carbon or nitrogen available allows a balanced growth of microorganisms. High carbon removal could be obtain in the C/N ratio 5 (71%). The filamentous cyanobacteria tend to exhibit less growth than unicellular forms, but they have interesting aggregation and sedimentation properties, fundamental for the industrial application of these microorganisms due to harvesting biomass from liquid medium. It is known that microalgae present a potential for various biotechnological applications from obtaining industrial bioproducts to wastewater treatment processes, highlighting itself in emerging biorefinery concept.