Hydrocarbon phenotyping of algal species using pyrolysis-gas chromatography mass spectrometry

Dinesh K Barupal,Do Yup Lee,Tobias Kind,Shankar L Kothari,Oliver Fiehn

doi:10.1186/1472-6750-10-40

Dinesh K Barupal, Do Yup Lee + Show 3 more

Open Access

https://doi.org/10.1186/1472-6750-10-40

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Abstract

BackgroundBiofuels derived from algae biomass and algae lipids might reduce dependence on fossil fuels. Existing analytical techniques need to facilitate rapid characterization of algal species by phenotyping hydrocarbon-related constituents.ResultsIn this study, we compared the hydrocarbon rich algae Botryococcus braunii against the photoautotrophic model algae Chlamydomonas reinhardtii using pyrolysis-gas chromatography quadrupole mass spectrometry (pyGC-MS). Sequences of up to 48 dried samples can be analyzed using pyGC-MS in an automated manner without any sample preparation. Chromatograms of 30-min run times are sufficient to profile pyrolysis products from C8 to C40 carbon chain length. The freely available software tools AMDIS and SpectConnect enables straightforward data processing. In Botryococcus samples, we identified fatty acids, vitamins, sterols and fatty acid esters and several long chain hydrocarbons. The algae species C. reinhardtii, B. braunii race A and B. braunii race B were readily discriminated using their hydrocarbon phenotypes. Substructure annotation and spectral clustering yielded network graphs of similar components for visual overviews of abundant and minor constituents.ConclusionPyrolysis-GC-MS facilitates large scale screening of hydrocarbon phenotypes for comparisons of strain differences in algae or impact of altered growth and nutrient conditions.

Highlights

Biofuels derived from algae biomass and algae lipids might reduce dependence on fossil fuels
Pyrolysis gas chromatography (GC)-MS automatically analyzes multiple samples without any pre-treatment Thermal pyrolysis of biological macromolecules produces volatile compounds that are detected by GC/ quadrupole MS for quantitative and qualitative characterization
Samples were subsequently freeze-dried and immersed into isopropanol for pyGC-MS analysis, without any extraction step that is known to add to analytical variance

Summary

Introduction

Biofuels derived from algae biomass and algae lipids might reduce dependence on fossil fuels. The world requires a sustainable source of energy for the future. Autotrophic organisms have been proposed to reduce the energy dependence of world economy on the fossil oil [1]. The hydrocarbon content of algae, fatty acids, isoprenoids and triacylglycerides [4], have the potential to compensate for future decline of crude oil production [5] if algae growth and harvest can be sustained under economically and energetically feasible parameters. Genetic and environmental factors affect the lipid constituents of microalgae [2,4] as well as algae biomass growth. Depending on the species-strains and conditions, lipids can constituent up to 80% of algal dry mass [2].

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