Background:
Biochemical conversion of lignocellulose hydrolysates remains challenging largely because most microbial processes have significantly reduced efficiency in the presence of both hexoses and pentoses. Thus, identification of microorganisms capable of efficient and simultaneous utilization of both glucose and xylose is pivotal.
Results:
In this work, we showed that the oleaginous yeast Trichosporon cutaneum AS 2.571 assimilated glucose and xylose simultaneously, and accumulated intracellular lipid up to 59 wt% with a lipid coefficient up to 0.17 g/g sugar, upon cultivation on a 2:1 glucose/xylose mixture in a 3-liter stirred tank bioreactor. In addition, no classical diauxic growth behavior was observed as microbial cell mass was increasing during the whole culture process without any lag periods. During shake flask cultures with different initial glucose/xylose ratios, glucose and xylose were consumed simultaneously at rates roughly proportional to their individual concentrations in the medium, leading to complete utilization of both sugars at the same time. Simultaneous utilization of glucose and xylose was also observed during corn stover hydrolysate fermentation with lipid content and coefficient of 39.2% and 0.15 g/g sugar, respectively. Lipid produced herein had fatty acid compositional profile similar to those of conventional vegetable oil, indicating that it could be explored as raw material for biodiesel production.
Conclusion:
Efficient lipid production with simultaneous consumption of glucose and xylose was achieved in this study. It provides an exciting opportunity to transform lignocellulosic materials into biofuel molecules and should also provoke further study to elucidate this unique sugar assimilation mechanism.Source:
http://www.biotechnologyforbiofuels.com/rss/