New insights into the CO2-steady and pH-steady cultivations of two microalgae based on continuous online parameter monitoring

Cao, Xupeng; Xi, Yimei; Liu, Jiao; Chu, Yong; Wu, Pei‐Chun; Yang, Miao; Chi, Zhanyou; Xue, Song

doi:10.1016/j.algal.2018.11.021

Cited by 26 publications

(20 citation statements)

References 19 publications

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“…Traditionally, pH is controlled by adding acid (including CO 2 ) or alkali, which usually incorporated a complex online monitoring system [20], making it difficult to be realized in large-scale cultivations especially when large open ponds are used. Recently, Zhu et al [21] established a recycling culture in which HCO 3 − was first used for microalgal growth followed by CO 2 neutralization for medium recycle.…”

Section: Introductionmentioning

confidence: 99%

Application of an in situ CO2–bicarbonate system under nitrogen depletion to improve photosynthetic biomass and starch production and regulate amylose accumulation in a marine green microalga Tetraselmis subcordiformis

Yao

Sun

et al. 2019

Biotechnol Biofuels

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Background Microalgal starch is regarded as a promising alternative to crop-based starch for biorefinery such as the production of biofuels and bio-based chemicals. The single or separate use of inorganic carbon source, e.g., CO 2 and NaHCO 3 , caused aberrant pH, which restricts the biomass and starch production. The present study applied an in situ CO 2 –NaHCO 3 system to regulate photosynthetic biomass and starch production along with starch quality in a marine green microalga Tetraselmis subcordiformis under nitrogen-depletion (−N) and nitrogen-limitation (±N) conditions. Results The CO 2 (2%)–NaHCO 3 (1 g L −1 ) system stabilized the pH at 7.7 in the −N cultivation, under which the optimal biomass and starch accumulation were achieved. The biomass and starch productivity under −N were improved by 2.1-fold and 1.7-fold, respectively, with 1 g L −1 NaHCO 3 addition compared with the one without NaHCO 3 addition. NaHCO 3 addition alleviated the high-dCO 2 inhibition caused by the single CO 2 aeration, and provided sufficient effective carbon source HCO 3 − for the maintenance of adequate photosynthetic efficiency and increase in photoprotection to facilitate the biomass and starch production. The amylose content was also increased by 44% under this CO 2 –bicarbonate system compared to the single use of CO 2 . The highest starch productivity of 0.73 g L −1 day −1 under −N cultivation and highest starch concentration of 4.14 g L −1 under ±N cultivation were both achieved with the addition of 1 g L −1 NaHCO 3 . These levels were comparable to or exceeded the current achievements reported in studies. The addition of 5 g L −1 NaHCO 3 under ±N cultivation led to a production of high-amylose starch (59.3% of total starch), which could be used as a source of functional food. Conclusions The in situ CO 2 –NaHCO 3 system significantly improved the biomass and starch production in T. subcordiformis . It could also regulate the starch quality with varied relative amylose content under different cultivation modes for diverse downstream applications that could promote the economic feasibility of microalgal starch-based biofuel production. Adoption of this system in T. subcordiformis would faci...

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Section: Introductionmentioning

confidence: 99%

Application of an in situ CO2–bicarbonate system under nitrogen depletion to improve photosynthetic biomass and starch production and regulate amylose accumulation in a marine green microalga Tetraselmis subcordiformis

Yao

Sun

et al. 2019

Biotechnol Biofuels

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“…These results show that F v /F m were negatively while NPQ were positively correlated with β-carotene accumulation under different stress conditions. It is found that F v /F m can be regarded as a stress indicator (Cao et al, 2019 ); the decrease of F v /F m suggested that the photosynthesis activity was arrested under N starvation, HL, and HS stress conditions. NPQ is a protection process that thermally dissipates excessive light energy absorbed by photosynthesis pigment (Wang et al, 2016 ).…”

Section: Resultsmentioning

confidence: 99%

ROS Induce β-Carotene Biosynthesis Caused by Changes of Photosynthesis Efficiency and Energy Metabolism in Dunaliella salina Under Stress Conditions

Kong

Chi

2021

Front. Bioeng. Biotechnol.

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The unicellular alga Dunaliella salina is regarded as a promising cell factory for the commercial production of β-carotene due to its high yield of carotenoids. However, the underlying mechanism of β-carotene accumulation is still unclear. In this study, the regulatory mechanism of β-carotene accumulation in D. salina under stress conditions was investigated. Our results indicated that there is a significant positive correlation between the cellular ROS level and β-carotene content, and the maximum quantum efficiency (Fv/Fm) of PSII is negatively correlated with β-carotene content under stress conditions. The increase of ROS was found to be coupled with the inhibition of Fv/Fm of PSII in D. salina under stress conditions. Furthermore, transcriptomic analysis of the cells cultivated with H2O2 supplementation showed that the major differentially expressed genes involved in β-carotene metabolism were upregulated, whereas the genes involved in photosynthesis were downregulated. These results indicated that ROS induce β-carotene accumulation in D. salina through fine-tuning genes which were involved in photosynthesis and β-carotene biosynthesis. Our study provided a better understanding of the regulatory mechanism involved in β-carotene accumulation in D. salina, which might be useful for overaccumulation of carotenoids and other valuable compounds in other microalgae.

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“…Both WT and P3-GAPDH were cultured for 96 h in a 1.5 L flat-plate poly (polymethyl methacrylate) (PMMA) photobioreactor (15.2 × 3.5 × 30 cm in length, width, and height) on Algal Station (AS) system, which was aired with 2% CO 2 compressed air as described previously ( Cao et al, 2019 ). The aeration rate was 0.4 vvm and supplied throughout the culture.…”

Section: Methodsmentioning

confidence: 99%

“…Here, the above C. reinhardtii strain, P3-GAPDH, was investigated by continuously monitoring its chlorophyll fluorescence dynamics, together with the fatty acids profiling changes to make a deeper understanding of physiological and biochemical aspects. Briefly, the C. reinhardtii CC137c (WT) and the dominant P3-GAPDH were parallelly evaluated by self-developed the Algal Station (AS) platform ( Cao et al, 2019 ) in 1.5 L bubbling flat-plate bioreactors under the mixotrophic cultivation modes in TAP medium. AS platform was developed by the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, and it’s the first commercial system to use the maximum quantum yield of photosynthesis II, F v /F m , as an online control parameter for microalgae cultivation together with light intensity, optical density (OD), pH, etc., and meets the requirement from lab to industry by South China University of Technology, Clean Energy Development Center of ENN Group and Microalgae Biotechnology Center of SDIC.…”

Section: Introductionmentioning

confidence: 99%

A Carbon Fixation Enhanced Chlamydomonas reinhardtii Strain for Achieving the Double-Win Between Growth and Biofuel Production Under Non-stressed Conditions

Zhu

Cao

et al. 2021

Front. Bioeng. Biotechnol.

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The stressed cultivations are widely used in microalgae R&D for the biofuel production with the repress on growth to a certain degree, which limits the overall productivity. The balance between the growth and energy storage compounds accumulation is a target needing the combination of both strain selection or construction and culture optimization. Here, an engineered strain of Chlamydomonas reinhardtii, in which the chloroplast type glyceraldehyde-3-phosphate dehydrogenase (cGAPDH) was overexpressed and named as P3-GAPDH, was cultured on the Algal Station platform. Compared with wild type (WT), C. reinhardtii CC137c, in Tris-acetate-phosphate (TAP) medium, the highest density of WT and P3-GAPDH were 1.23 ± 0.13 and 1.74 ± 0.09 g L–1 within 96 h, and the maximum biomass productivity was 24.30 ± 1.65 and 28.54 ± 1.43 mg L–1 h–1, respectively. In terms of the energy storage compounds, both carbohydrate and fatty acids content doubled in P3-GAPDH, from 0.13 ± 0.02 to 0.26 ± 0.04 g L–1 for carbohydrate and from 0.08 ± 0.01 to 0.16 ± 0.01 g L–1 for fatty acids, among which poly unsaturated fatty acids increased by 65.8%. Together with the continuous monitor of the chlorophyll fluorescence dynamics parameters Fv/Fm and Fv’/Fm’ and pH of culture, enhanced Calvin cycle by overexpressed cGAPDH promoted the carbon conversion and subsequent energy storage compounds accumulation. C. reinhardtii P3-GAPDH strain showed the potential as a good chassis with high carbon conversion ability.

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New insights into the CO2-steady and pH-steady cultivations of two microalgae based on continuous online parameter monitoring

Cited by 26 publications

References 19 publications

Application of an in situ CO2–bicarbonate system under nitrogen depletion to improve photosynthetic biomass and starch production and regulate amylose accumulation in a marine green microalga Tetraselmis subcordiformis

Application of an in situ CO2–bicarbonate system under nitrogen depletion to improve photosynthetic biomass and starch production and regulate amylose accumulation in a marine green microalga Tetraselmis subcordiformis

ROS Induce β-Carotene Biosynthesis Caused by Changes of Photosynthesis Efficiency and Energy Metabolism in Dunaliella salina Under Stress Conditions

A Carbon Fixation Enhanced Chlamydomonas reinhardtii Strain for Achieving the Double-Win Between Growth and Biofuel Production Under Non-stressed Conditions

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