Integrated thermal and biological conversion of microalgal proteins to lipids

Hull, Tobias C.; Knoshaug, Eric P.; Nelson, Robert S.; Wychen, Stefaine Van; Nagle, Nick; Kruger, Jacob S.; Dong, Tao

doi:10.1016/j.biortech.2025.132927

Integrated thermal and biological conversion of microalgal proteins to lipids

Journal Article · Tue Jul 01 00:00:00 EDT 2025 · Bioresource Technology

DOI:https://doi.org/10.1016/j.biortech.2025.132927· OSTI ID:2574723

^[1]; ^[2]; Nelson, Robert S. ^[2]; Wychen, Stefaine Van ^[2]; Nagle, Nick ^[2]; ^[2]; ^[2]

Colorado School of Mines, Golden, CO (United States); National Renewable Energy Laboratory (NREL), Golden, CO (United States)
National Renewable Energy Laboratory (NREL), Golden, CO (United States)

Microalgal composition varies with cultivation strategy, and low-cost approaches often produce high-protein biomass. This presents challenges for biorefineries designed around static, lipid-rich feedstocks. In particular, hydrolysates from high-protein algae are nitrogen-rich and sugar-poor, limiting microbial conversion and reducing product yields. This study develops a sequential thermal conditioning and biological upgrading strategy to integrate high-protein hydrolysate processing within conventional lipid extraction and upgrading designs. Oxidative deconstruction was used to break down proteins into ammonium and short-chain carboxylates. Ammonium was subsequently removed to yield a nitrogen-depleted, carboxylate-rich medium suitable for microbial lipid production. Bioconversion trials with Cutaneotrichosporon oleaginosum showed lipid accumulation only from hydrolysates treated with both oxidative deconstruction and nitrogen removal, reaching 1.2 g/L lipids at 30 % intracellular content. This integrated approach enables protein-to-lipid conversion and improves flexibility to process variable algal feedstocks, advancing fuel-oriented microalgal biorefineries.

View Accepted Manuscript (DOE)

Research Organization:: National Renewable Energy Laboratory (NREL), Golden, CO (United States)

Sponsoring Organization:: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Office of Sustainable Transportation. Bioenergy Technologies Office (BETO)

Grant/Contract Number:: AC36-08GO28308

OSTI ID:: 2574723

Report Number(s):: NREL/JA--5100-91429

Journal Information:: Bioresource Technology, Journal Name: Bioresource Technology Vol. 435; ISSN 0960-8524

Publisher:: ElsevierCopyright Statement

Country of Publication:: United States

Language:: English

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