Environmental Effects on Cell Composition

Hu, Qiang

doi:10.1002/9780470995280.ch5

Cited by 101 publications

(139 citation statements)

References 38 publications

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“…Although the occurrence and the extent to which TAG is produced appear to be species/strain-specific, and are ultimately controlled by the genetic make-up of individual organisms, oleaginous algae produce only small quantities of TAG under optimal growth or favorable environmental conditions (Hu, 2004). Synthesis and accumulation of large amounts of TAG accompanied by considerable alterations in lipid and fatty acid composition occur in the cell when oleaginous algae are placed under stress conditions imposed by chemical or physical environmental stimuli, either acting individually or in combination.…”

Section: Factors Affecting Triacylglycerol Accumulation and Fatty Acimentioning

confidence: 99%

Microalgal triacylglycerols as feedstocks for biofuel production: perspectives and advances

et al. 2008

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SummaryMicroalgae represent an exceptionally diverse but highly specialized group of micro-organisms adapted to various ecological habitats. Many microalgae have the ability to produce substantial amounts (e.g. 20-50% dry cell weight) of triacylglycerols (TAG) as a storage lipid under photo-oxidative stress or other adverse environmental conditions. Fatty acids, the building blocks for TAGs and all other cellular lipids, are synthesized in the chloroplast using a single set of enzymes, of which acetyl CoA carboxylase (ACCase) is key in regulating fatty acid synthesis rates. However, the expression of genes involved in fatty acid synthesis is poorly understood in microalgae. Synthesis and sequestration of TAG into cytosolic lipid bodies appear to be a protective mechanism by which algal cells cope with stress conditions, but little is known about regulation of TAG formation at the molecular and cellular level. While the concept of using microalgae as an alternative and renewable source of lipid-rich biomass feedstock for biofuels has been explored over the past few decades, a scalable, commercially viable system has yet to emerge. Today, the production of algal oil is primarily confined to high-value specialty oils with nutritional value, rather than commodity oils for biofuel. This review provides a brief summary of the current knowledge on oleaginous algae and their fatty acid and TAG biosynthesis, algal model systems and genomic approaches to a better understanding of TAG production, and a historical perspective and path forward for microalgae-based biofuel research and commercialization.

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Section: Factors Affecting Triacylglycerol Accumulation and Fatty Acimentioning

confidence: 99%

Microalgal triacylglycerols as feedstocks for biofuel production: perspectives and advances

et al. 2008

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“…In microalgae, sugars and polyols are commonly the most important osmoprotectants in response to salinity change (Hu, 2004). In diatoms, the only carbohydrate reported to accumulate as a response to salinity increases is mannose, in Cylindrotheca fusiformis (Paul, 1979).…”

Section: Uv Effects On Carbohydrate Compositionmentioning

confidence: 99%

Effects of UV radiation on five marine microphytobenthic Wadden sea diatoms, isolated from the Solthörn tidal flat (Lower Saxony, southern North Sea) – Part II: changes in carbohydrate, amino acid and fatty acid composition

Scholz

Rúa

Liebezeit

2014

European Journal of Phycology

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“…floridoside, isofloridoside), glycine betaine, homarine and cyclohexanetetrol are not. In microalgae, sugars and polyols are commonly the most important osmoprotectants in terms of cellular osmotic responses to a salinity change (Hu, 2004). Studies in vitro suggest that the polyols could serve as compatible solutes, acting as low-molecular-weight chaperones and as oxygen radical scavengers (Parida & Das, 2005).…”

Section: Importance Of Polyols Quaternary Ammonium and Tertiary Sulfmentioning

confidence: 99%

Compatible solutes in three marine intertidal microphytobenthic Wadden Sea diatoms exposed to different salinities

Scholz

Liebezeit

2012

European Journal of Phycology

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Diatoms inhabiting intertidal flats are subject to strongly changing salinities due to exposure to rain and desiccation at low tide. In order to determine the physiological responses of marine benthic diatoms to salinity changes, cultures of Navicula phyllepta, Achnanthes delicatula subsp. hauckiana and Nitzschia constricta, isolated from the Soltho¨rn tidal flat (lower Saxony, southern North Sea), were used to study the effect on growth rates of different salinities (0.5, 10, 20, 30, 40, 50). During short (1, 3, 10, 60 min) and long exposures (30 days), the composition of free amino acids and the accumulation of polyols, saccharides, quaternary ammonium compounds and -dimethylsulphoniopropionate (DMSP) were determined. The growth rates of N. phyllepta were not affected by salinity in the tested range, synthesizing and accumulating proline as the only response to salinity increases in the growth medium. The growth responses of A. delicatula subsp. hauckiana were significantly weaker at the lowest and highest salinities in comparison to the control treatment (at a salinity of 30), producing proline, glycine betaine, glycerol and the quaternary ammonium compound homarine. In contrast, N. constricta showed the highest growth rate in the low-salinity treatment and the lowest proline concentrations in the high-salinity assay in comparison to the other species. In addition, N. constricta was the only species that synthesized the tertiary sulphonium compound DMSP. Furthermore, results from the salinity treatments showed particular similarities in compound accumulation. While quaternary ammonium compounds as well as DMSP were synthesized during high-salinity treatments, polyols and carbohydrates were found predominantly in the low-salinity experiments. Enzyme activities specific to proline metabolism in A. delicatula and N. constricta indicated that the high salinity-induced free proline accumulation may be due to a stimulation of synthesis via the ornithine pathway, whereas in N. phyllepta the glutamate pathway may contribute significantly to the free proline accumulation. In conclusion, significant differences in osmolyte compositions were found in the three diatom species during exposure to different salinities, suggesting specific intracellular acclimation processes that provide possible explanations of the species' insensitivity towards environmental short-time salinity variations.

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Environmental Effects on Cell Composition

Cited by 101 publications

References 38 publications

Microalgal triacylglycerols as feedstocks for biofuel production: perspectives and advances

Microalgal triacylglycerols as feedstocks for biofuel production: perspectives and advances

Effects of UV radiation on five marine microphytobenthic Wadden sea diatoms, isolated from the Solthörn tidal flat (Lower Saxony, southern North Sea) – Part II: changes in carbohydrate, amino acid and fatty acid composition

Compatible solutes in three marine intertidal microphytobenthic Wadden Sea diatoms exposed to different salinities

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