Occurrence of glycerol uptake in <i><scp>D</scp>unaliella tertiolecta</i> under hyperosmotic stress

Lin, Huixin; Fang, Lei; Low, Chin Seng; Chow, Yvonne; Lee, Yuan Kun

doi:10.1111/febs.12100

Cited by 23 publications

(15 citation statements)

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“…Intracellular glycerol content has been found to increase with increasing content of NaCl in media [1][2][3]. It has been confirmed that yeast and other microorganisms also balance external osmotic pressure by synthesizing glycerol under hyperosmotic stress [4][5][6][7].…”

Section: Introductionmentioning

confidence: 84%

The relationship of glycerol and glycolysis metabolism patway under hyperosmotic stress in Dunaliella salina

et al. 2014

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This study detected the upstream and downstream key genes of glycolysis in Dunaliella Salina by using Real-time FluorescenceQuantitative PCR assays and measurement of enzyme activity. The results were as follows: the levels of transcription, enzyme activity, and protein of D. salina PFK were up-regulated under hyperosmotic stress while D. salina ENO were down-regulated. At the same time we monitored the change of intracellular degradation of starch, the synthesis of glycerol and PEP concentration in Dunaliella Salina under hyperosmotic stress. We found that lower expression of DsENO reduced the concentration of intracellular PEP which promoted the degradation of starch, and decreased the flow of carbon into the tricarboxylic acid cycle which would favor the synthesis of glycerol.

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Section: Introductionmentioning

confidence: 84%

The relationship of glycerol and glycolysis metabolism patway under hyperosmotic stress in Dunaliella salina

et al. 2014

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“…However, a recent study by Lin et al (2013) has reported on a homolog of the GUP1 (glycerol uptake) gene in Dunaliella tertiolecta which in yeast (i.e.…”

Section: Discussionmentioning

confidence: 99%

“…Saccharomyces cerevisiae) encodes the multi-membrane protein responsible for the proton symport of glycerol (Holst et al, 2000, Lucas et al, 1990, Bleve et al, 2005, Lin et al, 2013. The D.…”

Section: Discussionmentioning

confidence: 99%

“…DtGUP1 was found to share 40% homology with GUP1 found in S. cerevisiae and 50% identity with a membrane-bound O-acyltransferases family protein in C. reinhardtii. Whilst it is uncertain whether or not the assimilated glycerol is metabolically active within carbon metabolism, the authors do state that glycerol can be released back into the medium (Lin et al, 2013).…”

Section: Discussionmentioning

confidence: 99%

“…However it is unclear as to the fate of glycerol in some of these strains, whether it simply diffuses into the cell or is metabolically utilised either as an energy source or assimilated for biosynthesis. Whilst some species such as Dunaliella tertiolecta have been shown to import and release glycerol in response to hyperosmotic shock, they appear to be metabolically inactive (Lin et al, 2013). However, Dunaliella salina is reported to be able to reversibly metabolise glycerol from starch reserves in response to osmotic shock, which suggests that glycerol could indirectly be incorporated for the synthesis of other compounds (Borowitzka and Brown, 1974, Avron and Ben-Amotz, 1992, Craigie and McLachlan, 1964a).…”

Section: Carbon Fixation and Assimilationmentioning

confidence: 99%

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Enhanced microalgae growth and lipid production: a study of cytostatic inhibitors and glycerol assimilation

Zhang¹

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Current microalgal cultivation strategies and the unrefined oil produced (priced at ~USD$294/barrel) (Benemann et al, 2012), have yet to produce globally significant amounts of commercially viable biofuels competitive with fossil derived crude oil currently at (USD$45.22/barrel WTI (Nymex) as of 28.08.2015) (Nasdaq, 2015). Underlying this issue is the economics of gross lipid production, a function of lipid content and cellular productivity. The survival response of microalgal strains that promote the accumulation of carbon as lipids typically occurs under stress conditions (such as nutrient deficiency) at the expense of cellular growth. This study explored alternative strategies that inhibit metabolic processes, cell growth and division, through the use of cytostatic inhibitors such as sodium oxamate and conazole fungicides to induce lipid production in the absence of low nutrient conditions. Additionally, the exogenous supply of glycerol as a potential source of additional carbon was also investigated to improve photoautotrophic microalgae growth.An inducible trigger for the rerouting of carbon towards lipid synthesis under nutrient replete conditions has great potential for research and commercial applications of microalgal biofuels.Photoautotrophic growth of locally collected strains was optimised through nutrient screens and subsequently dosed using the tested inhibitors. The testing of these inhibitors showed that sodium oxamate was able to inhibit cell division and increase the lipid content in most of the tested microalgae strains. On the other hand, conazole treatment was largely observed to decrease the cellular biomass of the microalgae, which suggests that carbon assimilation may have been reduced.The results indicate that both types of inhibitors were able to cytostatically affect most of the tested strains and that a number of strains responded well with increased lipid production. This process has allowed us to test the effectiveness of the compounds and to identify potential high lipid producers. Some species of microalgae are able to supplement CO2 fixation with the utilisation of exogenous carbon substrates, typically acetate or glucose. By exploring their facultative heterotrophic capabilities, photoautotrophic limitations such as light shading may be overcome. From a biotechnological perspective it would be advantageous if waste carbon streams from other processes could be used to supplement microalgal growth. One such byproduct is glycerol from the biodiesel industry. The radiolabelled results validated that glycerol is assimilated into central metabolism of Chlorella protothecoides and may be able to contribute towards cellular growth.The data presented in this thesis highlights that the microalgal metabolic diversity for particular biotechnological applications can be probed and manipulated by utilising inhibitors and substrates known to function on specific metabolic pathways. In chapter two, the hypothesis that sodium 3 | P a g e oxamate can induce lipid production in microalga...

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Coping with High and Variable Salinity: Molecular Aspects of Compatible Solute Accumulation

Hagemann

2016

The Physiology of Microalgae

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Occurrence of glycerol uptake in Dunaliella tertiolecta under hyperosmotic stress

Cited by 23 publications

References 36 publications

The relationship of glycerol and glycolysis metabolism patway under hyperosmotic stress in Dunaliella salina

The relationship of glycerol and glycolysis metabolism patway under hyperosmotic stress in Dunaliella salina

Enhanced microalgae growth and lipid production: a study of cytostatic inhibitors and glycerol assimilation

Coping with High and Variable Salinity: Molecular Aspects of Compatible Solute Accumulation

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