Conversion of depolymerized sugars and aromatics from engineered feedstocks by two oleaginous red yeasts

Area of Science:

• Biotechnology and Bioengineering
• Microbiology
• Plant Science

Background:

• Efficient biological conversion of lignocellulose to bioproducts requires compatible biological catalysts.
• Pretreatment methods like ionic liquid, acid, or alkaline treatments are used to solubilize and depolymerize lignocellulose.
• Understanding microbial tolerance and assimilation of released compounds is crucial for optimizing bioprocesses.

Purpose of the Study:

• To evaluate the compatibility of red yeasts (Rhodosporidium toruloides and Rhodotorula mucilaginosa) with lignocellulose depolymerization products.
• To assess the ability of these yeasts to assimilate sugars, organic acids, and aromatic compounds released from engineered and wild-type Arabidopsis thaliana.
• To determine the potential of genetically-engineered red yeast strains in converting these assimilated compounds into biofuel precursors.

Main Methods:

• Utilized ionic liquid, acid, and alkaline pretreatments on engineered and wild-type Arabidopsis thaliana.
• Cultivated Rhodosporidium toruloides and Rhodotorula mucilaginosa on hydrolysates and synthetic media containing extracted compounds.
• Employed genetically-engineered yeast strains for conversion experiments.

Main Results:

• Both red yeast species tolerated and consumed monomeric sugars, organic acids, and specific aromatic compounds (4-hydroxybenzoic or protocatechuic acid) released from biomass.
• Genetically-engineered yeast strains successfully converted these depolymerized products into bisabolene, a biofuel precursor.
• The yeasts demonstrated assimilation capabilities on both hydrolysates and defined synthetic media.

Conclusions:

• Red yeasts Rhodosporidium toruloides and Rhodotorula mucilaginosa are suitable biological catalysts for lignocellulose bioconversion.
• These yeasts can effectively utilize a range of compounds released during biomass pretreatment, including those from engineered plants.
• Genetically-engineered strains show promise for the sustainable production of biofuel precursors like bisabolene from lignocellulosic biomass.