Harnessing the Effect of pH on Lipid Production in Batch Cultures of Yarrowia lipolytica SKY7
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The objective of this research was to investigate the kinetics of lipid production by Yarrowia lipolytica SKY7 in the crude glycerol-supplemented media with and without the control of pH. Lipid and citric acid production were improved with the pH control condition. There was no significant difference observed in the biomass concentration with or without the pH control. In the pH-controlled experiments, the biomass and lipid concentration reached 18 and 7.78 g/L, (45.5% w/w), respectively, with lipid yield (Yp/s) of 0.179 g/g at 60 h of fermentation. The lipid production was directly correlated with growth and the process was defined as growth associated. After 60 h of fermentation, the lipid degradation was noticed in the pH-controlled reactor whereas it occurred after 84 h in the pH-uncontrolled reactor. Apart from lipid, citric acid was produced as the major extracellular product in both fermentations but the much lower concentration in uncontrolled pH. Based on the experimental results, it is evident that controlling the pH will enhance the lipid production by 15% compared to pH-uncontrolled fermentation.
KeywordsY. lipolytica Crude glycerol Biodiesel Microbial lipid C/N ratio Effect of pH
The authors would like to acknowledge the Natural Sciences and Engineering Research Council of Canada (grant A4984, strategic grant 412994–11, Canada Research Chair) for financial support. We are grateful to the technical staffs of INRS-ETE for their timely help to analyze the samples on GC-FID.
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Conflict of Interest
All authors have read and agreed with the contents of the manuscript. The authors indicate no potential conflicts of interest.
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