Transcriptome and key genes expression related to carbon fixation pathways in Chlorella PY-ZU1 cells and their growth under high concentrations of CO2Report as inadecuate




Transcriptome and key genes expression related to carbon fixation pathways in Chlorella PY-ZU1 cells and their growth under high concentrations of CO2 - Download this document for free, or read online. Document in PDF available to download.

Biotechnology for Biofuels

, 10:181

First Online: 11 July 2017Received: 27 April 2017Accepted: 05 July 2017

Abstract

BackgroundThe biomass yield of Chlorella PY-ZU1 drastically increased when cultivated under high CO2 condition compared with that cultivated under air condition. However, less attention has been given to the microalgae photosynthetic mechanisms response to different CO2 concentrations. The genetic reasons for the higher growth rate, CO2 fixation rate, and photosynthetic efficiency of microalgal cells under higher CO2 concentration have not been clearly defined yet.

ResultsIn this study, the Illumina sequencing and de novo transcriptome assembly of Chlorella PY-ZU1 cells cultivated under 15% CO2 were performed and compared with those of cells grown under air. It was found that carbonic anhydrase CAs, enzyme for interconversion of bicarbonate to CO2 dramatically decreased to near 0 in 15% CO2-grown cells, which indicated that CO2 molecules directly permeated into cells under high CO2 stress without CO2-concentrating mechanism. Extrapolating from the growth conditions and quantitative Real-Time PCR of CCM-related genes, the Km CO2 the minimum intracellular CO2 concentration that rubisco required of Chlorella PY-ZU1 might be in the range of 80–192 μM. More adenosine triphosphates was saved for carbon fixation-related pathways. The transcript abundance of rubisco the most important enzyme of CO2 fixation reaction was 16.3 times higher in 15% CO2-grown cells than that under air. Besides, the transcript abundances of most key genes involved in carbon fixation pathways were also enhanced in 15% CO2-grown cells.

ConclusionsCarbon fixation and nitrogen metabolism are the two most important metabolisms in the photosynthetic cells. These genes related to the two most metabolisms with significantly differential expressions were beneficial for microalgal growth 2.85 g L under 15% CO2 concentration. Considering the micro and macro growth phenomena of Chlorella PY-ZU1 under different concentrations of CO2 0.04–60%, CO2 transport pathways responses to different CO2 0.04–60% concentrations was reconstructed.

KeywordsCO2 fixation pathway Genes transcript sequences 15% CO2 concentration Carbonic anhydrase Rubisco AbbreviationsCAscarbonic anhydrase

CCMCO2 concentrating mechanism

Km CO2concentration of CO2 required for 50% of the maximum photosynthesis rate

Rubiscoribulose-1,5-bisphosphate carboxylase-oxygenase

RuBPribulose-1,5-bisphosphate

3-PGA3-phosphoglyceride

DHAPdihydroxyacetone phosphate

S7Psedoheptulose-7-phosphate

fbaBfructose-1,6-bisphosphatase aldolase

Ru5Pribulose-5-phosphate

SBPasesedoheptulose-1,7-bisphosphatase

Electronic supplementary materialThe online version of this article doi:10.1186-s13068-017-0868-z contains supplementary material, which is available to authorized users.

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Author: Yun Huang - Jun Cheng - Hongxiang Lu - Yong He - Junhu Zhou - Kefa Cen

Source: https://link.springer.com/



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