The Potential of the Oil-Producing Oleaginous Yeast Rhodotorula mucilaginosa for Sustainable Production of Bio-Oil Energy

Shu-Yao Tsai,Chun-Ping Lin,Hsuan-Ti Yu

doi:10.3390/pr10020336

Abstract

At the 2021 United Nations Climate Change Conference (COP26), many countries in the world agreed to reach the goal of net-zero greenhouse gas emissions by 2050. This issue constrains energy use, petrochemical use, and related manufacturing production patterns. It is undeniable that the diesel engine of large equipment is still widely used in engineering applications, and it will not disappear in a short time. Many industrial projects still have to face the use of diesel engines. This study was focused on the development of oil-producing microorganisms to generate lipids. The oleaginous yeast Rhodotorula mucilaginosa (R. mucilaginosa) was selected for liquid-state cultivation, and the conditions for growth of the yeast cells were assessed. For the liquid fermentation culture with a fixed inoculation amount of 5%, it was determined that a suitable oil-producing culture was obtained on the sixth day, and the optimum conditions involved a carbon source concentration of 60 g/L, a yeast extract concentration of 0.5 g/L, and a KH2PO4 concentration of 7.0 g/L for each batch of culture experiments. In addition, the extraction method and solvent for the extraction of R. mucilaginosa lipids were chosen. The acid-heat method using the green organic solvent ethyl acetate exhibited the best performance for extraction of yeast lipids under environmentally friendly and safe conditions. The analysis of lipids showed that the fatty acids obtained primarily contained C16:0, C18:1 and C18:2, and especially C18:1 (41%) lipids, indicating that R. mucilaginosa lipids are a good bio-oil source for the production of biodiesel.

Highlights

Introduction published maps and institutional affilMicrobial oil is a renewable resource, so the use of microbial fermentation to produce bio-oil instead of using petroleum resources is of great significance [1]
R. mucilaginosa was in the biomass and lipid production increased rapidly when cultured for 2–4 days
R. mucilaginosa exhibited higher lipid accumulation under nitrogenrestricted conditions, but the increase in carbon-source concentration promoted the accumulation of lipids

Summary

Introduction

Introduction published maps and institutional affilMicrobial oil is a renewable resource, so the use of microbial fermentation to produce bio-oil instead of using petroleum resources is of great significance [1]. Oil-producing microorganisms, especially yeast, can produce large amounts of lipids and have a high growth rate spanning 24 continuous h, which makes the production times short and uniform, with no limiting requirements for cultivating space [2]. Rhodotorula mucilaginosa was used to produce single-cell lipids (SCOs), and the most suitable medium composition and lipid production conditions were found by exploring the different nutrient elements in the medium. The nature of fatty acids synthesized by oil-producing yeast depends on the nutrient content of the provided medium and on culture conditions [3,4,5,6,7,8,9,10]. The key factor affecting the biosynthetic pathway of R. mucilaginosa is the ratio of carbon to nitrogen [13]; medium iations

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