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Influence of nitrogen availability on biomass, lipid production, fatty acid profile, and the expression of fatty acid desaturase genes in Messastrum gracile SE-MC4

Anne-Marie K, Yee W, Loh SH, Aziz A, Cha TS

World J Microbiol Biotechnol, 2020 Jan 07;36(1):17.
PMID: 31912247 DOI: 10.1007/s11274-019-2790-y

In this study, the effects of limited and excess nitrate on biomass, lipid production, and fatty acid profile in Messastrum gracile SE-MC4 were determined. The expression of fatty acid desaturase genes, namely stearoyl-ACP desaturase (SAD), omega-6 fatty acid desaturase (ω-6 FAD), omega-3 fatty acid desaturase isoform 1 (ω-3 FADi1), and omega-3 fatty acid desaturase isoform 2 (ω-3 FADi2) was also assessed. It was found that nitrate limitation generally increased the total oil, α-linolenic acid (C18:3n3) and total polyunsaturated fatty acid (PUFA) contents in M. gracile. The reduction of nitrate concentration from 1.76 to 0.11 mM increased the total oil content significantly from 32.5 to 41.85% (dry weight). Palmitic (C16:0) and oleic (C18:1) acids as the predominant fatty acids in this microalgae constituted between 82 and 87% of the total oil content and were relatively consistent throughout all nitrate concentrations tested. The expression of SAD, ω-6 FAD, and ω-3 FADi2 genes increased under nitrate limitation, especially at 0.11 mM nitrate. The ω-3 FADi1 demonstrated a binary up-regulation pattern of expression under both nitrate-deficient (0.11 mM) and -excess (3.55 mM) conditions. Thus, findings from this study suggested that limited or excess nitrate could be used as part of a cultivation strategy to increase oil and PUFA content following media optimisation and more efficient culture methodology. Data obtained from the expression of desaturase genes would provide valuable insights into their roles under excess and limited nitrate conditions in M. gracile, potentially paving the way for future genetic modifications.
A brief period of darkness induces changes in fatty acid biosynthesis towards accumulation of saturated fatty acids in Chlorella vulgaris UMT-M1 at stationary growth phase

Cha TS, Yee W, Phua PSP, Loh SH, Aziz A

Biotechnol Lett, 2021 Apr;43(4):803-812.
PMID: 33438120 DOI: 10.1007/s10529-021-03077-2

OBJECTIVE: The effects of a brief (3 days) and prolonged (6 days) period of incubation in darkness and light on the biomass content, lipid content and fatty acid profile in Chlorella vulgaris UMT-M1 were determined.
RESULTS: Three days of incubation in darkness increased saturated fatty acid (SFA) content from 34.0 to 41.4% but decreased monounsaturated fatty acid (MUFA) content from 36.7 to 29.8%. Palmitic acid (C16:0) content was increased from 23.2 to 28.9%, whereas oleic acid (C18:1) content was reduced from 35.4 to 28.8%. Total oil content was slightly decreased from 20.4 to 18.7% after 3 days of darkness, without a significant reduction in biomass compared to 3 days of incubation in light. Biomass and oil content was highest in cultures incubated for 6 days in light, however the stimulatory and inhibitory effects of darkness (or light) on SFA and MUFA content was no longer present at 6 days of incubation.
CONCLUSIONS: Findings from this study suggests that fatty acid composition in C. vulgaris could be modulated to favor either C16:0 or C18:1 by a brief period of either darkness or light incubation, prior to harvesting.
Fulltext Transcriptomics de novo sequencing data of Messastrum gracile SE-MC4 under exponential and stationary growth stages

Afifudeen CLW, Loh SH, Wong LL, Aziz A, Takahashi K, Wahid MEA, et al.

Data Brief, 2021 Dec;39:107607.
PMID: 34869809 DOI: 10.1016/j.dib.2021.107607

Messastrum gracile SE-MC4 is a non-model microalga exhibiting superior oil-accumulating abilities. However, biomass production in M. gracile SE-MC4 is limited due to low cell proliferation especially after prolonged cultivation under oil-inducing culture conditions. Present data consist of next generation RNA sequencing data of M. gracile SE-MC4 under exponential and stationary growth stages. RNA of six samples were extracted and sequenced with insert size of 100 bp paired-end strategy using BGISEQ-500 platform to produce a total of 59.64 Gb data with 314 million reads. Sequences were filtered and de novo assembled to form 53,307 number of gene sequences. Sequencing data were deposited in National Center for Biotechnology Information (NCBI) and can be accessed via BioProject ID PRJNA552165. This information can be used to enhance biomass production in M. gracile SE-MC4 and other microalgae aimed towards improving biodiesel development.
Hispidacine, an unusual 8,4'-oxyneolignan-alkaloid with vasorelaxant activity, and hispiloscine, an antiproliferative phenanthroindolizidine alkaloid, from Ficus hispida Linn

Yap VA, Loong BJ, Ting KN, Loh SH, Yong KT, Low YY, et al.

Phytochemistry, 2015 Jan;109:96-102.
PMID: 25468714 DOI: 10.1016/j.phytochem.2014.10.032

Hispidacine, an 8,4'-oxyneolignan featuring incorporation of an unusual 2-hydroxyethylamine moiety at C-7, and hispiloscine, a phenanthroindolizidine alkaloid, were isolated from the stem-bark and leaves of the Malaysian Ficus hispida Linn. Their structures were established by spectroscopic analysis. Hispidacine induced a moderate vasorelaxant activity in rat isolated aorta, while hispiloscine showed appreciable antiproliferative activities against MDA-MB-231, MCF-7, A549, HCT-116 and MRC-5 cell lines.
Molecularly imprinted silica gel incorporated with agarose polymer matrix as mixed matrix membrane for separation and preconcentration of sulfonamide antibiotics in water samples

Rozaini MNH, Semail NF, Saad B, Kamaruzaman S, Abdullah WN, Rahim NA, et al.

Talanta, 2019 Jul 01;199:522-531.
PMID: 30952293 DOI: 10.1016/j.talanta.2019.02.096

Molecularly imprinted silica gel (MISG) was incorporated through dispersion in agarose polymer matrix to form a mixed matrix membrane (MMM) and was applied for the determination of three sulfonamide antibiotic compounds (i.e. sulfamethoxazole (SMX), sulfamonomethoxine (SMM), and sulfadiazine (SDZ)) from environmental water samples. Several important microextraction conditions, such as type of desorption solvent, extraction time, amount of sorbent, sample volume, pH, and effect of desorption time, were comprehensively optimized. A preconcentration factors of ≥ 20 was achieved by the extraction of 12.5 mL of water samples using the developed method. This microextraction-HPLC method demonstrated good linearity (1-500 μg L-1) with a coefficient of determination (R2) of 0.9959-0.9999, low limits of detection (0.06-0.17 μg L-1) and limits of quantification (0.20-0.56 μg L-1), good analyte recoveries (80-96%), and acceptable relative standard deviations (< 10%) under the optimized conditions. The method is systematically compared to those reported in the literature.