Selective fermentation of carbohydrate and protein fractions of Scenedesmus, and biohydrogenation of its lipid fraction for enhanced recovery of saturated fatty acids. Issue 2 (18th September 2015)

• Record Type: Journal Article
• Authors: Lai, YenJung Sean; Parameswaran, Prathap; Li, Ang; Aguinaga, Alyssa; Rittmann, Bruce E.
• Is Part Of: Biotechnology and bioengineering. Volume 113:Issue 2(2016)
• Page Start: 320
• Page End: 329
• Publication Date: 2015-09-18
• Subjects: fermentation -- lipids -- microbial community -- Scenedesmus; Biotechnology -- Periodicals; Bioengineering -- Periodicals; 660.6
• DOI: 10.1002/bit.25714
• Languages: English
• ISSNs: 0006-3592

Abstract

ABSTRACT: Biofuels derived from microalgae have promise as carbon‐neutral replacements for petroleum. However, difficulty extracting microalgae‐derived lipids and the co‐extraction of non‐lipid components add major costs that detract from the benefits of microalgae‐based biofuel. Selective fermentation could alleviate these problems by managing microbial degradation so that carbohydrates and proteins are hydrolyzed and fermented, but lipids remain intact. We evaluated selective fermentation of Scenedesmus biomass in batch experiments buffered at pH 5.5, 7, or 9. Carbohydrates were fermented up to 45% within the first 6 days, protein fermentation followed after about 20 days, and lipids (measured as fatty acid methyl esters, FAME) were conserved. Fermentation of the non‐lipid components generated volatile fatty acids, with acetate, butyrate, and propionate being the dominant products. Selective fermentation of Scenedesmus biomass increased the amount of extractable FAME and the ratio of FAME to crude lipids. It also led to biohydrogenation of unsaturated FAME to more desirable saturated FAME (especially to C16:0 and C18:0), and the degree of saturation was inversely related to the accumulation of hydrogen gas after fermentation. Moreover, the microbial communities after selective fermentation were enriched in bacteria from families known to perform biohydrogenation, i.e., Porphyromonadaceae and Ruminococcaceae . Thus, this study provides proof‐of‐concept that selective fermentation can improve the quantity and quality of lipids that can be extracted from Scenedesmus . Biotechnol. Bioeng. 2016;113: 320–329. © 2015 Wiley Periodicals, Inc. Abstract : Selective fermentation of Scenedesmus biomass generated volatile fatty acids from non‐lipid components but conserved the lipids. The fermentation increased the amount of extractable fatty acid methyl ester (FAME) but also led to biohydrogenation of unsaturated FAME to more desirable saturated FAME (especially to C16:0 and C18:0). Porphyromonadaceae and Ruminococcaceae as known families performing biohydrogenation were enriched in the microbial communities.