Production of lipid from depolymerised lignocellulose using the biocontrol yeast, Rhodotorula minuta: The fatty acid profile remains stable irrespective of environmental conditions

Abstract

The oleaginous yeast Rhodotorula minuta has been used previously as a biocide agent and for the production of β‐carotene. In addition, R. minuta has been shown to produce up to 40% lipids, while demonstrating a faster growth rate than the similar oleaginous yeasts; Lipomyces starkeyii and R. glutinis. In this study, this promising yeast was evaluated for its potential to produce glyceride lipids under the harsh conditions and complex sugar mixtures produced from depolymerised lignocellulose. The fatty acid profile of R. minuta was not found to change significantly irrespective of the environmental conditions and contained approximately 20% palmitic acid, 5% stearic acid, 60% oleic acid and 15% linolenic acid. R. minuta was found to grow on a range of sugars, and could consume xylose and glucose when both sugars were present; however, R. minuta was found to be highly sensitive to inhibitors, such as furfurals and organic acids, formed under the harsh lignocellulose depolymerisation conditions. Accordingly R. minuta did not grow well on biomass depolymerised with an acid pre‐treatment stage. However, R. minuta was cultured successfully on food waste depolymerised with no additional acids, producing up to 19 g/l cell mass with a lipid content of up to 25% of the dry cell weight. Practical applications: While high oil productivity, fast growth rates and a suitable fatty acid composition are key traits for the economic viability of SCO production, it is essential that the organism can be cultured and produce lipids from low‐cost substrates. This requires the ability to assimilate the nutrients present in the desired hydrolysate, as well as maintain high‐growth rates in the presence of inhibitory compounds produced during the hydrolysis process. In this paper, we demonstrate that the yeast R. minuta has industrial applicability in being able to convert depolymerised waste food to lipids with a profile akin to rapeseed oil. Rhodotorula minuta lipid cultured on depolymerised food waste.

Triauxic growth of an oleaginous red yeast Rhodosporidium toruloides on waste ‘extract’ for enhanced and concomitant lipid and β-carotene production

“…Glucose might have been valuable as a growth initiator but higher productivities were observed during the third log phase, which may be attributed to higher solubility and slower catabolism of glycerol. Between glucose and xylose a diauxic pattern of growth was reported earlier [ 38 ] in which one substrate was catabolized preferentially over the other with a lag phase occurring between the growth phases.…”

Toward a microbial palm oil substitute: oleaginous yeasts cultured on lignocellulose

“…Alternatively, Zygomycete sp., C. curvatus, C. oleophila, C. utilis, R. glutinis and R. toruloides could be made to produce more saturated lipids by altering the temperature of the fermentation . However, some oleaginous yeasts, such as R. minuta are not susceptible to changes in the lipid profile irrespective of the environmental conditions employed …”

An overview of the effects of fuel molecular structure on the combustion and emissions characteristics of compression ignition engines

“…22,23 Many methods of combined thermal, chemical and biological treatment of lignocellulosic biomass can produce ketones, short-chain fatty acid esters, acids, furans, methane and phenols. [24][25][26][27][28][29][30] With the development of various controlled processes for the conversion of renewable energy sources to liquid fuels for compression ignition engines, in contrast with current fossil diesel, at the point of production these future fuels will likely consist of a relatively small and discrete range of species, thereby enhancing the importance of the molecular structures of the compounds present to the overall fuel characteristics. This paper therefore presents a concise review of the effects of the molecular structures of fuels on the combustion characteristics and the exhaust emissions of NO x and Table 1.…”