FT-IR and GC–MS profiling of Aurantiochytrium sp. biomass cultivated on alternative carbon sources in a Wave Junk Fermentor

Abstract

Marine heterotrophic microalgae of the genus Aurantiochytrium are a renewable, contaminant-free platform for high-value lipids such as docosahexaenoic acid (DHA) and squalene. This study characterised the dried biomass of an indigenous Indonesian Aurantiochytrium sp. isolate, obtained from a Kupang mangrove ecosystem and cultivated in a low-shear, non-impeller Wave Junk Fermentor (registered industrial design IDD000067676). Within a circular-economy framework, the biomass was produced on different carbon sources and screened by high-throughput Fourier-transform infrared (FT-IR) spectroscopy, while its fatty-acid profile was examined by gas chromatography–mass spectrometry (GC–MS). FT-IR spectra of biomass grown on fructose (40 and 50 g/L) were essentially invariant to substrate concentration, whereas raising crude-glycerol concentration from 40 to 50 g/L shifted the O–H stretch from 3345 to 3361 cm⁻¹ and produced new bands at 2915 cm⁻¹ (aliphatic C–H) and 1043 cm⁻¹ (C–O), indicating stimulated de novo lipogenesis. GC–MS of the Glycerol 50 biomass (designated sample NIT1) gave library matches consistent with methyl docosapentaenoate (DPA; C22:5 ω-3) and, more tentatively, DHA (C22:6 ω-3), indicating the presence of long-chain polyunsaturated fatty acids in the lipid fraction. The reported library-match probabilities are identity confidence indices, not concentrations. The biomass FT-IR fingerprint closely resembled that of a premium commercial omega-3/DHA supplement, supporting the commercial potential of this locally sourced biomass as a sustainable feedstock for the pharmaceutical, functional-food and cosmetic sectors.