One-pot bioconversion of algae biomass into terpenes for advanced biofuels and bioproducts

Abstract

Under robust algae growth conditions, algal carbohydrates and proteins typically comprise up to ~ 80% of the ash-free dry weight of microalgae biomass. Therefore, production of algal biofuel through comprehensive utilization of all algal components and the addition of high energy density fuel compounds with "fit for purpose" properties or high-value bioproducts will both diminish the process cost and improve the overall process feasibility. In this study, we firstly demonstrated the concept of a "one-pot" bioconversion of algal carbohydrate and protein into value-added terpene compounds as advanced biofuel and high value bioproducts to improve the overall process feasibility through the development of engineered microbial consortium. The consortium for caryophyllene production yielded the highest titer of total terpene, up to 507.4 mg/L, including 471 mg/L of sesquiterpene, 36.4 mg/L of monoterpene, and 124.4 mg/L of caryophyllene on algal hydrolysate from Nannochloropsis sp. Additionally, the consortium expressing chamigrene synthase produced 187 mg/L total terpene including 87 mg/L of monoterpene, 100 mg/L of sesquiterpene, and 62 mg/L chamigrene on hydrolysate from benthic polyculture biomass. Compared to the yields of terpene extracted from plant tissue, both consortia increased the terpene yield about 3~40 times, which makes it a promising alternative pathway for terpene production.

Development of algae biorefinery concepts for biofuels and bioproducts; a perspective on process-compatible products and their impact on cost-reduction

“…The initial motivation for developing a conversion or fractionation approach was to create three different potential fuel streams: ethanol from fermenting the released carbohydrates, renewable diesel or jet fuel blendstock from the lipid fraction through hydrotreating and isomerization and finally, mixed alcohols (isobutanol, isopentanol, and others) from the protein fraction. 3,14,24,39 The first two fuel fractions (ethanol and renewable diesel or jet fuel blendstock) have been accounted for and demonstrated recently in a combined and integrated process. 3,14 The reports indicate a potential for 35% reduction in the overall minimum fuel selling price by combining both fuel fractions relative to a renewable diesel-only pathway.…”

“…243 Alternative bioproducts are pursued based on a similar protein (and carbohydrate) fermentation pathway, where instead of fusel alcohols, the production of terpenes was targeted. 39…”

Greener Terpene–Terpene Eutectic Mixtures as Hydrophobic Solvents

“…5 Pleasant aromas make terpenes and their mixtures essential in many commercial cleaning products, cosmetics, and perfumes. 6 In the area of fine chemicals, terpenes like myrcene were investigated as renewable alternatives to petrochemicals, 7 while Wu and Davis 8 revealed the bioconversion of algae biomass into terpenes for the production of high-energydensity aviation fuels. Due to their biodegradable character, terpenes are proposed as bio-derived alternatives to trichloroethane cleaning solvents.…”

Engineering Microbial Consortia for Bioconversion of Multisubstrate Biomass Streams to Biofuels

“…Similar E. coli cocultures were also developed for the production of terpene mixtures from the carbohydrate and protein fractions of algae hydrolysates [62,63]. In these works, the caryophyllene biosynthesis pathway was engineered into the carbohydrate conversion strain and the protein conversion strain respectively.…”