Towards a Microbial Production of Fatty Acids as Precursors of Biokerosene from Glucose and Xylose
Résumé
The aviation industry considers the development of sustainable biofuels as one of the
biggest challenges of the next ten years. The aim is to lower the environmental impact of
the steadily increasing use of fossil fuels on climate change, yielding greater energy
independence and fuel security. Thus, the development of a new route for the production of
lipids from renewable non-food resources is now being promoted with the recent ASTM
certification of hydrotreated oils. Our study focuses on the potential of growth of the
oleaginous yeast Rhodotorula glutinis using glucose and xylose which can come from
renewable lignocellulosic substrates and of lipid accumulation using glucose as substrate.
Experiments were carried out in fed-batch mode which allowed feed flux management. Carbon
fluxes were controlled with modifying xylose/glucose ratios to quantify metabolism in
optimal growth condition. Besides, the management of carbon and nitrogen fluxes allowed
characterizing lipid accumulation. Thus, it has been shown that the yeast Rhodotorula
glutinis can simultaneously consume glucose and xylose. When the ratio xylose/glucose
increased, the growth rate and the carbon conversion yield into biomass decreased: it was
of 0.36 h-1 and 0.64 Cmol x*.Cmol glu-1 for pure glucose, it was of 0.15 h-1 and 0.56
Cmol.Cmol-1 for 10% xylose and it was of 0.037
h-1 and 0.18 Cmol.Cmol-1 for pure xylose.
The necessity to maintain residual growth and to manage carbon fluxes to optimize lipid
accumulation performance was revealed. Lipid accumulation on glucose engendered a final
biomass concentration of 150 gCDW.L-1, microbial production (72% of
lipids) and maximal productivity over 1.48 glip.L-1.h-1.
The culture temperature is an important parameter to modulate the lipid profile. The
results were encouraging. Lipid accumulation using lignocellulosic feedstock was shown to
be a highly promising route.
Origine : Publication financée par une institution
