Microalgae are a promising alternative for sustainable biofuel production, but production yields and costs present a significant bottleneck. Here, the use of glycerol and xylose to boost the lipid yield was evaluated using ten strains from the Universite de Montreal collection of microalgae. This report shows that some microalgal strains are capable of mixotrophic and heterotrophic growth on xylose, the major carbon source found in wastewater streams from pulp and paper industries, with an increase in growth rate of 2.8-fold in comparison to photoautotrophic growth, reaching up to mu = 1.1/d. On glycerol, growth rates reached as high as mu = 1.52/d. Lipid productivity increased up to 370% on glycerol and 180% on xylose for the strain LB1H10, showing the suitability of this strain for further development of biofuels production through mixotrophic cultivation. (C) 2014 Elsevier Ltd. All rights reserved.