Background: Recently, a newly isolated oleaginous yeast strain Scheffersomyces segobiensis DSM 27193 was identified with the capability of accumulating high contents of palmitoleic acid (POA) in its intracellular lipid (13.8%). However, high amounts of ethanol as the main by-product were also produced in this system. To eliminate ethanol formation and to further improve POA production, process optimization focused on dissolved oxygen (DO) regulation was conducted in this study.Results: As a result, agitation control was found to be highly beneficial for cell growth and lipid production. When keeping pO2>40% through dynamic agitation control, significant improvements toward lipid (70.12% increase) and POA (1.44 fold) production have been obtained, and the accumulation of ethanol was decreased to 2.3 g/L. While increasing the aeration rate to 2 vvm, no significant decrease has been found in ethanol accumulation. Further application of a two-stage agitation regulation (600 rpm in the first 48 h fermentation then adjusted the agitation speed to 1000 rpm) gave 10.23 g/L of lipid (50% increase) with 2.02 g/L of POA (1.15 fold) production. At last, under the best condition of 1000 rpm of agitation and 1 vvm of aeration, no ethanol was detected during the whole fermentation process, while a dry biomass concentration of 44.8 g/L with 13.43 g/L of lipid and 2.93 g/L of POA was achieved. Transcription analysis revealed that ethanol synthetic pathway was down regulated under the condition of high agitation, while the expression of the key enzymes responsible for lipid and POA accumulation were enhanced.Conclusion: This study introduces the oleaginous yeast chassis S. segobiensis DSM 27193 and an effective pO2 regulation strategy for efficient biological production of POA.
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