Ultrahigh‐cell‐density heterotrophic cultivation of the unicellular green alga <i>Chlorella sorokiniana</i> for biomass production

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The unicellular flagellate algae Poterioochromonas malhamensis is a potential fucoxanthin-rich resource for sustainable and cost-effective fucoxanthin production. Light and nutrients are critical regulators for the accumulation of fucoxanthin in P. malhamensis. In this study, the maximum fucoxanthin yield of 50.5 mg L−1 and productivity of 6.31 mg L−1 d−1 were achieved by coupling high-cell-density fermentation with illumination. It was found that the combined use of organic and inorganic nitrogen (N) nutrition could improve the fucoxanthin yield as single inorganic or organic N had limitation to enhance cell growth and fucoxanthin accumulation. White light was the optimal light quality for fucoxanthin accumulation. Under white light and a moderate light intensity of 150 μmol m−2 s−1, the highest biomass concentration and fucoxanthin content reached 32.9 g L−1 and 1.56 mg g−1 of dry cell weight (DCW), respectively. This is the first study on effective fucoxanthin production in P. malhamensis by integrating illumination with high-cell-density fermentation, which paved the way for further development of P. malhamensis as a potential source for commercial fucoxanthin production.

Section: Comparison Of Fucoxanthin Production By P Malhamensis With O...supporting

confidence: 60%

“…Biomass concentration was determined with GF/C filter paper as described in our previous report (Jin et al, 2021). Briefly, 1 ml of the culture was collected to centrifuge at 4,000 rpm for 3 min.…”

Section: Determination Of Biomass Concentration Cell Number and Gluco...mentioning

confidence: 99%

Effective fucoxanthin production in the flagellate alga Poterioochromonas malhamensis by coupling heterotrophic high-cell-density fermentation with illumination

Guo

et al. 2022

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“…Usually, to achieve the fast growth, the optimal C/N ratio was kept for both initial batch medium and concentrated feeding medium ( Jin et al, 2020 ). Meanwhile, to maintain the C/N ratio constant, sodium hydroxide (NaOH) and potassium hydroxide (KOH) are two common alkali used for pH adjustment ( Xiong et al, 2008 ; Jin et al, 2021 ; Ma et al, 2021 ). Obviously, exogenous ions (Na + or K + ) would be introduced to the medium during this pH adjustment.…”

Section: Discussionmentioning

confidence: 99%

Heterotrophically Ultrahigh-Cell-Density Cultivation of a High Protein-Yielding Unicellular Alga Chlorella With a Novel Nitrogen-Supply Strategy

Hou

Chen

et al. 2021

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The unicellular green alga Chlorella is an ideal protein source. However, the high production cost and low production capability of the current main photoautotrophic culture mode limit its application especially as an alternative protein source for food and feed, which might be overcome through high-cell-density cultivation in fermenters. In this study, a Chlorella sorokiniana strain CMBB276 with high protein content was selected from five Chlorella strains by comprehensive evaluation of their growth rates, protein contents, and yields. The optimal cultural temperature, pH, and mole ratio of carbon and nitrogen (C/N) for C. sorokiniana CMBB276 growth were found to be 30°C, 6.5, and 18, respectively. Ammonium chloride was proved to be the best nitrogen (N) source for C. sorokiniana CMBB276 growth, whereas growth inhibition caused by the accumulation of salts was observed under fed-batch cultivation when maintaining a constant C/N ratio of 18 by controlling pH with sodium hydroxide solution. By simultaneously reducing the concentration of ammonium chloride in the feeding medium and controlling pH with ammonium hydroxide, we finally achieved the ultrahigh-cell-density cultivation of C. sorokiniana CMBB276. The highest biomass concentration and protein yield reached 232 and 86.55 g l−1, respectively, showing the great potential of culturing C. sorokiniana CMBB276 in fermenters for economic and large-scale protein source production.

“…Numerous studies have demonstrated the biotechnical significance of heterotrophic cultivation for microalgal biomass and chemicals production ( Lee Chang et al, 2015 ; Morales-Sánchez et al, 2015 ; Hu et al, 2018 ). Through optimizing the components of growth media and substrate feeding strategy, ultra-high biomass yield (>200 g L −1 ) can be achieved for several production strains such as Chlorella sorokiniana ( Jin et al, 2021 ), Chlorella sorokiniana strain CMBB276 ( Xu et al, 2021 ) and Scenedesmus acuminatus ( Jin et al, 2020 ). The capabilities of these species in achieving such high biomass yield have been attributable to the highly active starch biosynthesis under heterotrophic conditions, considering the carbon substrate (i.e.…”

Section: Introductionmentioning

confidence: 99%

Effective Two-Stage Heterotrophic Cultivation of the Unicellular Green Microalga Chromochloris zofingiensis Enabled Ultrahigh Biomass and Astaxanthin Production

Chen

et al. 2022

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Chromochloris zofingiensis has obtained particular interest as a promising candidate for natural astaxanthin production. In this study, we established a two-stage heterotrophic cultivation process, by using which both the growth of C. zofingiensis and astaxanthin accumulation are substantially enhanced. Specifically, the ultrahigh biomass concentration of 221.3 g L−1 was achieved under the optimum culture conditions in 7.5 L fermenter during 12 days. When scaled-up in the 500 L fermentor, the biomass yield reached 182.3 g L−1 in 9 days, while the astaxanthin content was 0.068% of DW. To further promote astaxanthin accumulation, gibberellic Acid-3 (GA3) was screened from a variety of phytohormones and was combined with increased C/N ratio and NaCl concentration for induction. When C. zofingiensis was grown with the two-stage cultivation strategy, the astaxanthin yield reached 0.318 g L−1, of which the biomass yield was 235.4 g L−1 and astaxanthin content was 0.144% of DW. The content of the total fatty acids increased from 23 to 42% of DW simultaneously. Such an astaxanthin yield was 5.4-fold higher than the reported highest record and surpassed the level of Haematococcus pluvialis. This study demonstrated that heterotrophic cultivation of C. zofingiensis is competitive for industrial astaxanthin production.