Regulation of starch and lipid accumulation in a microalga Chlorella sorokiniana

Li, Tingting; Gargouri, Mahmoud; Feng, Jie; Park, Jeong Jin; Gao, Difeng; Miao, Chao; Dong, Tao; Gang, David R.; Chen, Shulin

doi:10.1016/j.biortech.2015.01.005

Cited by 111 publications

(41 citation statements)

References 33 publications

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“…9c, d, f–i) at day 8. It is indicated that the starch was degraded and lipid content was increased in microalgae which was also proved for C. sorokiniana [27], S. obliquus [28], and C. zofingiensis [29]. The possible mechanism of carbohydrate or starch accumulation is shown in Figs.…”

Section: Resultsmentioning

confidence: 78%

Improving carbohydrate and starch accumulation in Chlorella sp. AE10 by a novel two-stage process with cell dilution

Cheng

Yuan

et al. 2017

Biotechnol Biofuels

121

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BackgroundMicroalgae are highly efficient cellular factories that capture CO2 and are also alternative feedstock for biofuel production. Carbohydrates, proteins, and lipids are major biochemical components in microalgae. Carbohydrates or starch in microalgae are possible substrates in yeast fermentation for biofuel production. The carbon partitioning in microalgae could be regulated through environmental stresses, such as high concentration of CO2, high light intensity, and nitrogen starvation conditions. It is essential to obtain carbohydrate-rich microalgae via an optimal bioprocess strategy.ResultsThe carbohydrate accumulation in a CO2 tolerance strain, Chlorella sp. AE10, was investigated with a two-stage process. The CO2 concentration, light intensity, and initial nitrogen concentration were changed drastically in both stages. During the first stage, it was cultivated over 3 days under 1% CO2, a photon flux of 100 μmol m−2 s−1, and 1.5 g L−1 NaNO3. It was cultivated under 10% CO2, 1000 μmol m−2 s−1, and 0.375 g L−1 NaNO3 during the second stage. In addition, two operation modes were compared. At the beginning of the second stage of mode 2, cells were diluted to 0.1 g L−1 and there was no cell dilution in mode 1. The total carbohydrate productivity of mode 2 was increased about 42% compared with that of mode 1. The highest total carbohydrate content and the highest starch content of mode 2 were 77.6% (DW) and 60.3% (DW) at day 5, respectively. The starch productivity was 0.311 g L−1 day−1 and the total carbohydrate productivity was 0.421 g L−1 day−1 in 6 days.ConclusionsIn this study, a novel two-stage process was proposed for improving carbohydrate and starch accumulation in Chlorella sp. AE10. Despite cell dilution at the beginning of the second stage, environmental stress conditions of high concentration of CO2, high light intensity, and limited nitrogen concentration at the second stage were critical for carbohydrate and starch accumulation. Although the cells were diluted, the growths were not inhibited and the carbohydrate productivity was improved. These results were helpful to establish an integrated approach from CO2 capture to biofuel production by microalgae.

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Section: Resultsmentioning

confidence: 78%

Improving carbohydrate and starch accumulation in Chlorella sp. AE10 by a novel two-stage process with cell dilution

Cheng

Yuan

et al. 2017

Biotechnol Biofuels

121

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“…Starch and lipid accumulation are associated in Chlorella (Mizuno et al 2013, Takeshita et al 2014, Li et al 2015. Starch is the primary product of photosynthesis and is metabolized to fatty acids through acetyl-CoA.…”

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confidence: 99%

A Simple Method for Measuring the Starch and Lipid Contents in the Cell of Microalgae

et al. 2015

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SummaryWe used a microplate-based method to quantify microalgal lipids with Nile Red staining and a fluorescence microplate reader. However, a method to quantify starch that combines microplates with staining has not been reported. Therefore, we examined microplate-based quantification of lipids using Nile Red staining and of starch using Lugol staining. Neither starch nor lipids accumulated during the zero phase of cultured Parachlorella kessleri, only starch accumulated during the starch phase, and starch was subsequently lost and lipids accumulated during the oil phase. The quantities of starch and lipids were measured using a microplate-based method, which indicated linear production of starch and lipids within limited ranges (lipids, 0.071-0.380 g mL 1 ; starch, 155-404 mg mL 1 ) when standard curves were prepared for lipids extracted with methyl tertiary-butyl ether and for starch extracted with anthrone. The concentration of starch produced during the starch phase was 0.59 mg mL 1 and that of lipids during the oil phase was 2.49 mg mL 1. The concentration of starch produced was 0.05-0.13 mg mL 1 during phases other than the starch phase, and lipids were not detected other than during the oil phase because lipid contents were approximated based on the quantity of triacylglycerol, which stains with Nile Red.

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“…In addition, the decreased protein degradation and two key enzymes of the glyoxylate cycle, link beta-oxidation, the degradation of fatty acids, with gluconeogenesis and carbon storage. It has been found by Li et al [65] that biosynthesis of starch and lipids benefits in the microalga Chlorella sorokiniana from a more active photosynthesis. Although, the increased expression of enzymes of the glycerophospholipid metabolism indicates a build-up of fatty acids for membrane biosynthesis potentially for growth and cell division, no other pathway indicates growth such as the biosynthesis of amino acids, nucleotides or ribosomes.…”

Section: Discussionmentioning

confidence: 99%

Quantitative Proteomics Reveals Ecophysiological Effects of Light and Silver Stress on the Mixotrophic Protist Poterioochromonas malhamensis

et al. 2017

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Aquatic environments are heavily impacted by human activities including climate warming and the introduction of xenobiotics. Due to the application of silver nanoparticles as bactericidal agent the introduction of silver into the environment strongly has increased during the past years. Silver ions affect the primary metabolism of algae, in particular photosynthesis. Mixotrophic algae are an interesting test case as they do not exclusively rely on photosynthesis which may attenuate the harmful effect of silver. In order to study the effect of silver ions on mixotrophs, cultures of the chrysophyte Poterioochromonas malhamensis were treated in a replicate design in light and darkness with silver nitrate at a sub-lethal concentration. At five time points samples were taken for the identification and quantitation of proteins by mass spectrometry. In our analysis, relative quantitative protein mass spectrometry has shown to be a useful tool for functional analyses in conjunction with transcriptome reference sequences. A total of 3,952 proteins in 63 samples were identified and quantified, mapping to 4,829 transcripts of the sequenced and assembled transcriptome. Among them, 720 and 104 proteins performing various cellular functions were differentially expressed after eight days in light versus darkness and after three days of silver treatment, respectively. Specifically pathways of the energy and primary carbon metabolism were differentially affected by light and the utilization of expensive reactions hints to an energy surplus of P. malhamensis under light conditions. The excess energy is not invested in growth, but in the synthesis of storage metabolites. The effects of silver were less explicit, observable especially in the dark treatments where the light effect could not mask coinciding but weaker effects of silver. Photosynthesis, particularly the light harvesting complexes, and several sulphur containing enzymes were affected presumably due to a direct interference with the silver ions, mainly affecting energy supply.

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Regulation of starch and lipid accumulation in a microalga Chlorella sorokiniana

Cited by 111 publications

References 33 publications

Improving carbohydrate and starch accumulation in Chlorella sp. AE10 by a novel two-stage process with cell dilution

Improving carbohydrate and starch accumulation in Chlorella sp. AE10 by a novel two-stage process with cell dilution

A Simple Method for Measuring the Starch and Lipid Contents in the Cell of Microalgae

Quantitative Proteomics Reveals Ecophysiological Effects of Light and Silver Stress on the Mixotrophic Protist Poterioochromonas malhamensis

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