Hemiselmis andersenii and Chlorella stigmatophora As New Sources of High‐value Compounds: A Lipidomic Approach

Abstract

To unlock the potential of Chlorella stigmatophora (Trebouxiophyceae, Chlorophyta) and Hemiselmis andersenii (Cryptophyceae, Cryptophyta) as natural reactors for biotechnological exploitation, their lipophilic extracts were characterized using Fourier Transform Infrared spectroscopy with Attenuated Total Reflectance (FTIR-ATR) and Gas Chromatography-Mass Spectrometry (GC-MS) before and after alkaline hydrolysis. The GC-MS analysis enabled the identification of 62 metabolites-namely fatty acids (27), aliphatic alcohols (17), monoglycerides (7), sterols (4), and other compounds (7). After alkaline hydrolysis, monounsaturated fatty acids increased by as much as 87%, suggesting that the esterified compounds were mainly neutral lipids. Hemiselmis andersenii yielded the highest Σω3/Σω6 ratio (7.26), indicating that it is a good source of ω3 fatty acids, in comparison to C. stigmatophora (Σω3/Σω6 = 1.24). Both microalgae presented significant amounts of aliphatic alcohols (6.81-10.95 mg Á g dw −1), which are recognized by their cholesterol-lowering properties. The multivariate analysis allowed visualization of the chemical divergence among H. andersenii lipophilic extracts before and after alkaline hydrolysis, as well as speciesspecific differences. Chlorella stigmatophora showed to be a valuable source of essential fatty acids for nutraceuticals, whereas H. andersenii, due to its high chemical diversity, seems to be suitable for different fields of application.

Comparative lipidomic analysis of Chlorella stigmatophora and Hemiselmis cf. andersenii in response to nitrogen-induced changes

“…Then, trimethylsilyl (TMS) derivatives were analyzed in a gas chromatographer (6890N, Agilent Technologies, China) equipped with a mass selective detector (5973Network, Agilent Technologies, USA) and a ValcoBond capillary column from Vici Valco (30 m × 0.25 mm inner diameter, 0.25 μm film thickness). The chromatographic conditions were those described in Fernandes et al [19]. Briefly, the oven was set to 80 • C for 5 min, increasing by 4 • C min − 1 until 208 • C, then by 2 • C min − 1 until 260 • C and by 5 • C min − 1 until the final temperature of 300 • C, which was maintained for 4 min.…”

“…andersenii samples were more affected by alkaline hydrolysis than C. stigmatophora samples. Alkaline hydrolysis targets the ester bonds of lipids like acylglycerols, wax, and sterols esters [19]. Thus, the small changes verified for C. stigmatophora samples after alkaline hydrolysis might be justified by its lipid composition being richer in non-acyl lipids (like alkylglycerols) and lipid soluble compounds (such as carotenoids), which are stable to alkaline hydrolysis [19].…”

“…andersenii at high nitrogen supplementation a suitable microalgal strain for ω3 fatty acid supplementation. ω6 predominantly dominates Western diets, with its consumption being 20 times higher than that of ω3 fatty acids [19]. However, as main precursors of pro-and anti-inflammatory molecules (e.g.…”

“…However, as main precursors of pro-and anti-inflammatory molecules (e.g. prostaglandins, and leukotrienes), a balanced Σω3/Σω6 ratio close to 1:1 is recommended for the mitigation of inflammatory and chronic diseases [19]. Thus, the cultivation of H. cf.…”

“…In aquaculture industry, Hemiselmis is used as feed for fish hatcheries to improve growth and survival rates [18]. Although previous studies [17,19] have reported Cryptophyte Hemiselmis species as promising candidates for the sustainable and profitable production of health-promoting lipids, the modulation of Hemiselmis lipid quantity and composition is understudied. In this context, lipidomic studies are essential not only to reveal potential targets that may be of commercial interest, but also to understand lipid regulation in microalgae [20].…”