Utilization of biodiesel-derived glycerol or xylose for increased growth and lipid production by indigenous microalgae

• Indigenous strains were screened for utilization of glycerol and xylose.
• Yields of lipids and biomass are likely to be improved in future optimization studies.
• Lipid productivity from glycerol of some was higher than previously reported.
• One strain gained increased biomass in the light with both xylose and glycerol.
• For the first time xylose utilization by a microalga is shown.

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 Université de Montréal 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 μ = 1.1/d. On glycerol, growth rates reached as high as μ = 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.