Molecular Mechanism of Lipid Accumulation and Metabolism of Oleaginous Chlorococcum sphacosum GD from Soil under Salt Stress

Abstract

The oleaginous microalgae species Chlorococcum sphacosum GD is a promising feedstock for biodiesel production from soil. However, its metabolic mechanism of lipid production remains unclear. In this study, the lipid accumulation and metabolism mechanisms of Chlorococcum sphacosum GD were analyzed under salt stress based on transcriptome sequencing. The biomass and lipid content of the alga strain were determined under different NaCl concentrations, and total RNA from fresh cells were isolated and sequenced by HiSeq 2000 high throughput sequencing technology. As the salt concentration increased in culture medium, the algal lipid content increased but the biomass decreased. Following transcriptome sequencing by assembly and splicing, 24,128 unigenes were annotated, with read lengths mostly distributed in the 200–300 bp interval. Statistically significant differentially expressed unigenes were observed in different experimental groups, with 2051 up-regulated genes and 1835 down-regulated genes. The lipid metabolism pathway analysis showed that, under salt stress, gene-related fatty acid biosynthesis (ACCase, KASII, KAR, HAD, FATA) was significantly up-regulated, but some gene-related fatty acid degradation was significantly down-regulated. The comprehensive results showed that salt concentration can affect the lipid accumulation and metabolism of C. sphacosum GD, and the lipid accumulation is closely related to the fatty acid synthesis pathway.

The inhibition and recovery mechanisms of the diatom Phaeodactylum tricornutum in response to high light stress – A study combining physiological and transcriptional analysis

“…In recent years, the development of transcriptomics technology has promoted the study of the gene functions of various biological processes in microalgae. To date, the molecular mechanisms and relevant genes of microalgae responding to heavy metals, salt, pollutants, and some other stress conditions have been reported (Su et al, 2021; Tripathi & Poluri, 2021; Zhao, Tang, Lv, et al, 2020). For high light stress, Nymark et al (2009) combined global transcriptional profiling and metabolite profiling analysis and observed that Phaeodactylum tricornutum went through three phases of photoacclimation after transferring from 35 μmol photons · m −2 · s −1 to 500 μmol photons · m −2 · s −1 .…”

Survival mechanism of a novel marine multistress-tolerant Meyerozyma guilliermondii GXDK6 under high NaCl stress as revealed by integrative omics analysis

“…In addition, the types of organic acids (12) and lipids (six) increased by more than 2-folds when GXDK6 was stressed by 10% NaCl. Therefore, the accumulation of organic acids and lipids is likely beneficial to GXDK6 to increase its resistance to salt stress (30). Among the metabolites, glycerol was found as the consistent product when the NaCl concentration was increased from 0% to 10%; the corresponding glycerol decreased from 14.99% to 8.88%, with a decrease by 40.76%, demonstrating that glycerol is one of the important substances in response to salt tolerance (31).…”

Latest Expansions in Lipid Enhancement of Microalgae for Biodiesel Production: An Update

“…The main enzyme involved in the precursor formation and lipid synthesis are ACCase, ATP citrate lyase (ACL), glycerol-3-phosphate (GPAT), lysophosphatidic acid acyltransferase (LPAAT), phospholipid: diacylglycerols acyltransferase (PDAT), and acyl-Co-A: diacylglycerols acyltransferase (DGAT) [52][53][54]. The expression of these gene-encoding enzymes determines lipid content, and the regulation of these genes affects lipid content [55,56].…”