Abstract

BACKGROUND: Lipids produced from oleaginous yeasts are a promising alternative to terrestrial oils. Despite promising cellular yields of lipid however, an industrial process remains elusive. One key processing bottleneck is the need to provide nutrient-rich conditions for cellular growth and then extended nutrient-depleted conditions for lipid accumulation. Surprisingly, investigations detailing process development, particularly with a focus on kinetics, are rare in this field.

RESULTS: In this investigation we report on the unique oleaginous yeast Metschnikowia pulcherrima, where lipid accumulation ≥ 29.8% (w/w) was achieved without apparent nutrient limitation. The process was developed in stirred tank reactors through determining the influence of temperature, pH and nutrition on lipid production. A temperature of up to 25 °C and initial pH 5 could be applied to enhance initial reaction kinetics. Through the increased supply of yeast extract of up to 5% (w/w) of glucose, a maximum lipid production rate of 0.60 g L−1 h−1 (4 h-average), productivity of 0.29 g L−1 h−1, and yield of 0.17 g g−1 glucose were achieved – the highest yet recorded with this yeast. Suitable to combat the excessive secretion of polyols of up to 0.11 g g−1 glucose was an excess nutrient supply as well as a low cultivation temperature of 15 °C and moderate pH 5.
CONCLUSIONS: This study demonstrates that the lack of a starvation stage, coupled with effective process development is required for oleaginous yeasts to achieve the yields and productivities required for commercial lipid production.
Original languageEnglish
Pages (from-to)1163-1172
JournalJournal of Chemical Technology and Biotechnology
Volume95
Issue number4
Early online date28 Jan 2020
DOIs
Publication statusPublished - 30 Apr 2020

Keywords

  • microbial lipids
  • arabitol
  • glycerol
  • kinetics
  • yields
  • nutrient limitation

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