Analysis of Starch Content in Chlorella Pyrenoidosa (Chlorophyta) by Morphological and Quantitative Techniques

Rosen, Barry H.; Berliner, Martha D.; Petro, Michael J.

doi:10.1002/j.1537-2197.1986.tb10878.x

Cited by 5 publications

(1 citation statement)

References 17 publications

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“…However, there is evidence for starch turnover in Chlorella spp. during growth in response to light intensity or nutritional status (Rosen et al, 1986;Fan et al, 2012b). In our experiments, the starch content of C. pyrenoidosa cells showed a comparable decrease between the exponential and stationary phases of heterotrophic growth (48-72 h; Fig.…”

Section: How Was Starch Synthesized?supporting

confidence: 64%

Genomic Foundation of Starch-to-Lipid Switch in Oleaginous Chlorella spp.

et al. 2015

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The ability to rapidly switch the intracellular energy storage form from starch to lipids is an advantageous trait for microalgae feedstock. To probe this mechanism, we sequenced the 56.8-Mbp genome of Chlorella pyrenoidosa FACHB-9, an industrial production strain for protein, starch, and lipids. The genome exhibits positive selection and gene family expansion in lipid and carbohydrate metabolism and genes related to cell cycle and stress response. Moreover, 10 lipid metabolism genes might be originated from bacteria via horizontal gene transfer. Transcriptomic dynamics tracked via messenger RNA sequencing over six time points during metabolic switch from starch-rich heterotrophy to lipid-rich photoautotrophy revealed that under heterotrophy, genes most strongly expressed were from the tricarboxylic acid cycle, respiratory chain, oxidative phosphorylation, gluconeogenesis, glyoxylate cycle, and amino acid metabolisms, whereas those most down-regulated were from fatty acid and oxidative pentose phosphate metabolism. The shift from heterotrophy into photoautotrophy highlights up-regulation of genes from carbon fixation, photosynthesis, fatty acid biosynthesis, the oxidative pentose phosphate pathway, and starch catabolism, which resulted in a marked redirection of metabolism, where the primary carbon source of glycine is no longer supplied to cell building blocks by the tricarboxylic acid cycle and gluconeogenesis, whereas carbon skeletons from photosynthesis and starch degradation may be directly channeled into fatty acid and protein biosynthesis. By establishing the first genetic transformation in industrial oleaginous C. pyrenoidosa, we further showed that overexpression of an NAD(H) kinase from Arabidopsis (Arabidopsis thaliana) increased cellular lipid content by 110.4%, yet without reducing growth rate. These findings provide a foundation for exploiting the metabolic switch in microalgae for improved photosynthetic production of food and fuels.

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Section: How Was Starch Synthesized?supporting

confidence: 64%

Genomic Foundation of Starch-to-Lipid Switch in Oleaginous Chlorella spp.

et al. 2015

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Isolation and characterization of a starchless mutant of Chlorella pyrenoidosa STL‐PI with a high growth rate, and high protein and polyunsaturated fatty acid content

Ramazanov

2006

Phycological Research

108

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The growth characteristics, biochemical composition and ultrastructure of a novel starchless mutant of Chlorella pyrenoidosa, designated as STL-PI, are compared to the same characteristics of its parental strain, C. pyrenoidosa 82T. The STL-PI mutant had a 22 ± 5% higher growth rate, and 24.5 ± 4.2% more protein than the parental strain, 82T. Furthermore, the STL-PI mutant accumulated 20.4% more polyunsaturated fatty acids and 18% less saturated fatty acids than the parental 82T. When the parental 82T was cultured in a nitrogen-free media, their starch content increased from 6.8 ± 2.8% to 22.5 ± 3.1%. In contrast, the STL-PI mutant produced no starch, regardless of the growth conditions. Instead, the mutant cells responded to nitrogen limitation by further increasing their lipid content from 25.2 ± 1.2% to 38.0 ± 2.3% per dry weight. Transmission electron micrography revealed that nitrogen limitation typically stimulates the formation of starch granules in the chloroplast of 82T cells. Yet no starch granules were observed in the STL-PI cells. Instead, only the formation of large lipid globules was observed in the mutant cells. These results demonstrate that the starchless mutant STL-P1 possesses novel physiological and phytochemical properties distinct from the 82T cells: their cells were deficient in starch synthesis and showed higher growth rates and productivity than 82T cells.

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Morphometric analysis of reserve substances and ultrastructural changes during caulogenic determination and loss of competence of Eastern White pine (Pinus strobus) cotyledons in vitro

Flinn¹,

Webb²,

Newcomb³

1989

Can. J. Bot.

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Lipid, starch, and protein reserves were monitored cytochemically and, along with certain ultrastructural changes, were quantified morphometrically during adventitious shoot determination or loss of competence in cotyledons from cultured Pinus strobus zygotic embryos. Initial expiants were rich in lipid, which declined during culture. There was more lipid retention in explants on cytokinin medium by day 5 than on basal medium. However, by day 7, five- and six-celled clusters showed greater lipid utilization than most other cells on cytokinin, which may have indicated a shift towards shoot determination in these cells. Except for an initially greater retention on cytokinin, a similar pattern for storage protein degradation was observed in both treatments. Starch levels increased during culture, but did not differ between treatments during the first 7 days. Vacuolation increased during culture and was greater on basal medium than on cytokinin. Relative nuclear size also increased, but was greater on cytokinin. Relative mitochondrial area increased during culture, except in noncluster cells on basal medium. While few differences were noted between cell types within each treatment, distinct differences in nuclear size, vacuolation, and lipid content existed between cells on cytokinin and basal medium. These coincided with the timing of caulogenic determination in cytokinin-treated expiants. The loss of lipid reserves, as well as ultrastructural changes associated with the maturation of cells on basal medium, was associated with the loss of competence.

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Analysis of Starch Content in Chlorella Pyrenoidosa (Chlorophyta) by Morphological and Quantitative Techniques

Cited by 5 publications

References 17 publications

Genomic Foundation of Starch-to-Lipid Switch in Oleaginous Chlorella spp.

Genomic Foundation of Starch-to-Lipid Switch in Oleaginous Chlorella spp.

Isolation and characterization of a starchless mutant of Chlorella pyrenoidosa STL‐PI with a high growth rate, and high protein and polyunsaturated fatty acid content

Morphometric analysis of reserve substances and ultrastructural changes during caulogenic determination and loss of competence of Eastern White pine (Pinus strobus) cotyledons in vitro

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