C/N ratio and carbon source-dependent lipid production profiling in Rhodotorula toruloides
Journal article, 2020

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.

Carbon to nitrogen ratio

Biorefineries

Genome-scale metabolic model

Flux balance analysis

Alternative substrates

Rhodotorula toruloides

Microbial oil

Author

Helberth Júnnior Santos Lopes

University of Tartu

State University of Campinas

Nemailla Bonturi

University of Tartu

Eduard Kerkhoven

Chalmers, Biology and Biological Engineering, Systems and Synthetic Biology

Everson Alves Miranda

State University of Campinas

Petri-Jaan Lahtvee

University of Tartu

Applied Microbiology and Biotechnology

0175-7598 (ISSN) 1432-0614 (eISSN)

Vol. 104 2639-2649

Subject Categories

Renewable Bioenergy Research

Chemical Process Engineering

Bioenergy

DOI

10.1007/s00253-020-10386-5

PubMed

31980919

More information

Latest update

3/10/2020