C/N ratio and carbon source-dependent lipid production profiling in Rhodotorula toruloides

Author(s)

Santos Lopes, Helberth Junnior ^{[1, 2]} ; Bonturi, Nemailla ^[2] ; Kerkhoven, Eduard Johannes ^{[3, 4]} ; Miranda, Everson Alves ^[1] ; Lahtvee, Petri-Jaan ^[2]

Affiliation

^[1] Univ Estadual Campinas, Sch Chem Engn, Dept Mat & Bioproc Engn, BR-13083970 Campinas, SP - Brazil

^[2] Univ Tartu, Inst Technol, Tartu - Estonia

^[3] Chalmers Univ Technol, Novo Nordisk Fdn Ctr Biosustainabil, Gothenburg - Sweden

^[4] Chalmers Univ Technol, Dept Biol & Biol Engn, Gothenburg - Sweden

• Document type: Journal article
• Source: Applied Microbiology and Biotechnology; v. 104, n. 6 JAN 2020.
• Web of Science Citations: 0

Abstract

Microbial oils are lipids produced by oleaginous microorganisms, which can be used as a potential feedstock for oleochemical production. The oleaginous yeast Rhodotorula toruloides can co-produce microbial oils and high-value compounds from low-cost substrates, such as xylose and acetic acid (from hemicellulosic hydrolysates) and raw glycerol (a byproduct of biodiesel production). One step towards economic viability is identifying the best conditions for lipid production, primarily the most suitable carbon-to-nitrogen ratio (C/N). Here, we aimed to identify the best conditions and cultivation mode for lipid production by R. toruloides using various low-cost substrates and a range of C/N ratios (60, 80, 100, and 120). Turbidostat mode was used to achieve a steady state at the maximal specific growth rate and to avoid continuously changing environmental conditions (i.e., C/N ratio) that inherently occur in batch mode. Regardless of the carbon source, higher C/N ratios increased lipid yields (up to 60% on xylose at a C/N of 120) but decreased the specific growth rate. Growth on glycerol resulted in the highest specific growth and lipid production (0.085 g lipids/gDW{*}h) rates at C/Ns between 60 and 100. We went on to study lipid production using glycerol in both batch and fed-batch modes, which resulted in lower specific lipid production rates compared with turbisdostat, however, fed batch is superior in terms of biomass production and lipid titers. By combining the data we obtained in these experiments with a genome-scale metabolic model of R. toruloides, we identified targets for improvements in lipid production that could be carried out either by metabolic engineering or process optimization. (AU)

• FAPESP's process: 16/10636-8 - From the cell factory to the Biodiesel-Bioethanol integrated biorefinery: a systems approach applied to complex problems in micro and macroscales
• Grantee: Roberto de Campos Giordano
• Support Opportunities: Program for Research on Bioenergy (BIOEN) - Thematic Grants