11 research outputs found

    Metabolic plasticity of the starchless mutant of Chlorella sorokiniana and mechanisms underlying its enhanced lipid production revealed by comparative metabolomics analysis

    No full text
    The unicellular green alga Chlorella sorokiniana is of great industrial interest for biofuels production due to its rapid growth, high lipid content, and capabilities in tolerating broad environment and cultivation conditions. C. sorokiniana can grow under both heterotrophic and photoautotrophic conditions, which offers opportunities to produce lipids from this species/strain by employing coupled heterotrophic and phototrophic cultivation mode. In this study, a starchless mutant SLM2 was successfully obtained by high-throughput screening of the chemical mutagenesis pool of a C. sorokiniana strain that has the potential to achieve high cell density under heterotrophic conditions, aiming to enhance its lipid content and productivity. Unexpectedly, enhanced lipid production was only observed in photoautrophically-grown SLM2 cells subjected to stress conditions (i.e. high-light and nutrient limitation). When the heterotrophically-grown cells were subjected to the same stress conditions that can trigger lipid accumulation, less differences in lipid productivities were observed between wild type (WT) and SLM2. To understand metabolic basis underlying such a discrepancy, comparative time-course metabolomics analysis was performed for SLM2 and WT from different cultivation conditions. The results highlighted up-regulated metabolic flux related to the increased lipid biosynthesis in the phototrophically-grown starchless mutant cells, which included enhanced oxidative pentose phosphate pathway in a mode favoring NADPH production, and the augmented glycolysis pathway providing precursors for both fatty acids and glycerol backbone synthesis. In SLM2, the classical TCA cycle is down-regulated, while its bypass the gamma-aminobutyric acid (GABA) shunt is triggered, which is speculated to contribute to enhanced lipid accumulation in the starchless mutant as well. In addition to revealing the metabolic plasticity possessed by starchless mutant, it is suggested that photoautotrophic cultivation mode is more suitable than coupled heterotrophic and photoautotrophic cultivation mode for production of lipids by using the starchless mutant SLM2 obtained in this study

    Metabolic plasticity of the starchless mutant of Chlorella sorokiniana and mechanisms underlying its enhanced lipid production revealed by comparative metabolomics analysis

    Get PDF
    The unicellular green alga Chlorella sorokiniana is of great industrial interest for biofuels production due to its rapid growth, high lipid content, and capabilities in tolerating broad environment and cultivation conditions. C. sorokiniana can grow under both heterotrophic and photoautotrophic conditions, which offers opportunities to produce lipids from this species/strain by employing coupled heterotrophic and phototrophic cultivation mode. In this study, a starchless mutant SLM2 was successfully obtained by high-throughput screening of the chemical mutagenesis pool of a C. sorokiniana strain that has the potential to achieve high cell density under heterotrophic conditions, aiming to enhance its lipid content and productivity. Unexpectedly, enhanced lipid production was only observed in photoautrophically-grown SLM2 cells subjected to stress conditions (i.e. high-light and nutrient limitation). When the heterotrophically-grown cells were subjected to the same stress conditions that can trigger lipid accumulation, less differences in lipid productivities were observed between wild type (WT) and SLM2. To understand metabolic basis underlying such a discrepancy, comparative time-course metabolomics analysis was performed for SLM2 and WT from different cultivation conditions. The results highlighted up-regulated metabolic flux related to the increased lipid biosynthesis in the phototrophically-grown starchless mutant cells, which included enhanced oxidative pentose phosphate pathway in a mode favoring NADPH production, and the augmented glycolysis pathway providing precursors for both fatty acids and glycerol backbone synthesis. In SLM2, the classical TCA cycle is down-regulated, while its bypass the gamma-aminobutyric acid (GABA) shunt is triggered, which is speculated to contribute to enhanced lipid accumulation in the starchless mutant as well. In addition to revealing the metabolic plasticity possessed by starchless mutant, it is suggested that photoautotrophic cultivation mode is more suitable than coupled heterotrophic and photoautotrophic cultivation mode for production of lipids by using the starchless mutant SLM2 obtained in this study

    Artificial switches induce the bespoke production of functional compounds in marine microalgae Chlorella by neutralizing CO2

    No full text
    Abstract To improve the CO2 tolerance of a marine microalga Chlorella sp. of which the production capacity has been demonstrated industrially, a mutant library was created and a strain hct53 was screened. Compared to the parental strain, hct53 shows a high CO2 capture capacity, while starch biosynthesis is compromised, with increases in health beneficial metabolites and antioxidant capacity. Global gene expression and genome-wide mutation distribution revealed that transcript choreography was concomitant with more active CO2 sequestration, an increase in the lipid synthesis, and a decrease in the starch and protein synthesis. These results suggest that artificial trait improvement via mutagenesis, couple with multiomics analysis, helps discover genetic switches that induce the bespoke conversion of carbon flow from “redundant metabolites” to valuable ones for functional food

    Construction of an Aptamer–SiRNA Chimera-Modified Tissue-Engineered Blood Vessel for Cell-Type-Specific Capture and Delivery

    No full text
    The application of tissue-engineered blood vessels (TEBVs) is the main developmental direction of vascular replacement therapy. Due to few and/or dysfunctional endothelial progenitor cells (EPCs), it is difficult to successfully construct EPC capture TEBVs in diabetes. RNA has a potential application in cell protection and diabetes treatment, but poor specificity and low efficiency of RNA transfection <i>in vivo</i> limit the application of RNA. On the basis of an acellular vascular matrix, we propose an aptamer–siRNA chimera-modified TEBV that can maintain a satisfactory patency in diabetes. This TEBV consists of two parts, CD133-adenosine kinase (ADK) chimeras and a TEBV scaffold. Our results showed that CD133-ADK chimeras could selectively capture the CD133-positive cells <i>in vivo</i>, and then captured cells can internalize the bound chimeras to achieve RNA self-transfection. Subsequently, CD133-ADK chimeras were cut into ADK siRNA by a dicer, resulting in depletion of ADK. An ADK-deficient cell may act as a bioreactor that sustainably releases adenosine. To reduce nonspecific RNA transfection, we increased the proportion of HAuCl<sub>4</sub> during the material preparation, through which the transfection capacity of polyethylenimine (PEI)/polyethylene glycol (PEG)-capped gold nanoparticles (PEI/PEG-AuNPs) was significantly decreased and the ability of TEBV to resist tensile and liquid shear stress was greatly enhanced. PEG and 2′-<i>O</i>-methyl modification was used to enhance the <i>in vivo</i> stability of RNA chimeras. At day 30 postgrafting, the patency rate of CD133-ADK chimera-modified TEBVs reached 90% in diabetic rats and good endothelialization was observed
    corecore