Microalgae have great potential as alternative productive platforms for sustainable production of bioenergy, food, feed and other commodities. Process optimization to realize the claimed potential often comprises strains selection and improvement and also developing of more efficient cultivation, harvesting and downstream processing technology. In this work we show that inoculation with the bacterium Rhizobium strain 1011 resulted in increments of up to 30% in chlorophyll, biomass and lipids accumulation of the oleaginous microalgae Ankistrodesmus sp. strain SP2-15. Inoculated cultures have reached a high lipid productivity of up to 112 mg L-1 d(-1) after optimization. The resulting biomass presented significant levels of Omega 3 fatty acids including stearidonic acid, suggesting potential as an alternative land-based source of essential fatty acids. (c) 2013 Elsevier Ltd. All rights reserved.