Corn stover variability drives differences in bisabolene production by engineered Rhodotorula toruloides.

Area of Science:

• Biotechnology
• Microbiology
• Biochemical Engineering

Background:

• Microbial conversion of lignocellulosic biomass offers a sustainable route for biofuels.
• Rhodotorula toruloides is engineered for bisabolene production, a sustainable aviation fuel precursor.
• Feedstock heterogeneity significantly impacts bioconversion efficiency, but is understudied.

Purpose of the Study:

• To investigate how variations in corn stover batches, anatomical fractions, and storage conditions affect bisabolene production by R. toruloides.
• To understand the influence of feedstock heterogeneity on microbial growth and product titer.
• To correlate protein expression changes with feedstock variations.

Main Methods:

• Corn stover feedstocks underwent deacetylation, mechanical refining, and enzymatic hydrolysis.
• Engineered R. toruloides fermented hydrolysates to produce bisabolene.
• Global protein expression analysis (proteomics) was used to compare microbial responses.

Main Results:

• Bisabolene production varied significantly based on corn stover source and fraction.
• The stalk fraction of corn stover hydrolysate yielded the maximum bisabolene (8.89 ± 0.47 g/L).
• Proteomics revealed significant upregulation/downregulation of proteins involved in carbohydrate metabolism, energy production, and ion transport.

Conclusions:

• Feedstock heterogeneity presents complex challenges and opportunities for bisabolene production.
• R. toruloides exhibits coordinated metabolic responses to feedstock variations, such as iron-sulfur cluster protein regulation.
• Optimizing feedstock selection and pretreatment is crucial for enhancing bisabolene yield and bioprocess economics.