Special Issue "Biology of Microalgae and Cyanobacteria and Their Biotechnological Potential"

A special issue of Life (ISSN 2075-1729). This special issue belongs to the section "Microbiology".

Deadline for manuscript submissions: 31 August 2022 | Viewed by 6731

Special Issue Editors

Dr. Felix Krujatz
E-Mail Website1 Website2
Guest Editor
1. Technical University of Dresden, Institute of Natural Materials Technology, Dresden, Germany
2. biotopa gGmbH - Center for Applied Aquaculture & Bioeconomy, Radeberg, Germany
Interests: microalgae; photobioreactor; biorefinery; co-cultures; single-cell analysis; biosystems engineering; bioprocess monitoring
Dr. Steffen Braune
E-Mail Website1 Website2
Guest Editor
Institute of Biotechnology, Chair of Molecular Cell Biology, Brandenburg University of Technology Cottbus-Senftenberg, Germany
Interests: cyanobacteria; microalgae; bioactive and pharmacoactive metabolites, thrombogenicity; blood platelets; blood plasma proteins
Dr. Dorina Strieth
E-Mail Website
Guest Editor
Technical University of Kaiserslautern, Chair of Bioprocess Engineering, Kaiserslautern, Germany
Interests: phototrophic biofilms; cyanobacteria; photobioreactors; aerosol photobioreactors; co-cultivation; EPS; pigments

Special Issue Information

Dear Colleagues,

Phototrophic microorganisms, such as microalgae and cyanobacteria, require only light, CO2, water and a few inorganic molecules or elements for growth and production of value-added cell metabolites. Over the last several decades, cultivation of these has, therefore, evolved into a globally established, economically important branch of biotechnology. A better understanding of metabolic pathways and metabolite production will lead to improved assessments of aquatic primary production. From a biotechnological perspective, a better understanding will lead to improved yield and the ability to manipulate algal growth for bio-production purposes.
Many microalgae and cyanobacteria are amenable to genetic manipulation. For instance, the genomes of more than 190 cyanobacteria have been sequenced to date, and genomic-based analyses are being applied to document their changing transcriptome, proteome and metabolome. Genetic engineering now opens an avenue to further improve the biomass and will ultimately aid in manipulation of selected strains for biotechnological applications in protein production, bioremediation, biofuel, and pharmaceutical production.
For this Special Issue we welcome research papers and reviews for following topics:

  • Improving production of biomass (e.g., process and reactor design);
  • Use of microalgae and cyanobacteria for the permanent sequestration of CO2;
  • Use of microalgae and cyanobacteria as cell factories for the direct bioconversion of CO2 into valuable substances (by natural or synthetic metabolic processes);
  • Innovative downstream processing concepts (cell disruption, extraction of metabolites, and milking);
  • Biological and pharmacological effects of cell ingredients such as phycobiliproteins (in vitro and in vivo);
  • Extremophilic (e.g., thermophilic, acidophilic, and cryophilic) and terrestrial microalgae and cyanobacteria for biotechnological applications;
  • Co-culture and synergistic biological systems for biotechnological applications, e.g., marine sponges/marine snails/plants/plant tissue cells.

Dr. Felix Krujatz
Dr. Steffen Braune
Dr. Dorina Striehth
Guest Editors

Manuscript Submission Information

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Keywords

  • microalgae
  • cyanobacteria
  • biotechnology
  • culturing conditions
  • downstream processing
  • biomass production
  • CO2 sequestration and bioconversion
  • bioactive and pharmacoactive substances
  • extremophiles

Published Papers (8 papers)

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Research

Jump to: Review

Article
The Assessment of the Real-Time Radiative Properties and Productivity of Limnospira platensis in Tubular Photobioreactors
Life 2022, 12(7), 1014; https://doi.org/10.3390/life12071014 - 08 Jul 2022
Viewed by 392
Abstract
The development of tools to predict the photobioreactors’ (PBRs) productivity is a significant concern in biotechnology. To this end, it is required to know the light availability inside the cultivation unit and combine this information with a suitable kinetic expression that links the [...] Read more.
The development of tools to predict the photobioreactors’ (PBRs) productivity is a significant concern in biotechnology. To this end, it is required to know the light availability inside the cultivation unit and combine this information with a suitable kinetic expression that links the distribution of radiant energy with the cell growth rate. In a previous study, we presented and validated a methodology for assessing the radiative properties necessary to address the light distribution inside a PBR for varying illuminating conditions through the cultivation process of a phototrophic microorganism. Here, we sought to utilise this information to construct a predictive tool to estimate the productivity of an autotrophic bioprocess carried out in a 100 [L] tubular photobioreactor (TPBR). Firstly, the time-dependent optical properties over ten batch cultures of L. platensis were calculated. Secondly, the local volumetric rate of photon absorption was assessed based on a physical model of the interaction of the radiant energy with the suspended biomass, together with a Monte Carlo simulation algorithm. Lastly, a kinetic expression valid for low illumination conditions has been utilised to reproduce all the cultures’ experimentally obtained dry weight biomass concentration values. Taken together, time-dependent radiative properties and the kinetic model produced a valuable tool for the study and scaling up of TPBRs. Full article
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Communication
Influence of Different Light-Emitting Diode Colors on Growth and Phycobiliprotein Generation of Arthrospira platensis
Life 2022, 12(6), 895; https://doi.org/10.3390/life12060895 - 15 Jun 2022
Viewed by 438
Abstract
Light-emitting diodes (LED) can be utilized as tailorable artificial light sources for the cultivation of cyanobacteria such as Arthrospira platensis (AP). To study the influence of different LED light colors on phototrophic growth and biomass composition, AP was cultured in closed bioreactors and [...] Read more.
Light-emitting diodes (LED) can be utilized as tailorable artificial light sources for the cultivation of cyanobacteria such as Arthrospira platensis (AP). To study the influence of different LED light colors on phototrophic growth and biomass composition, AP was cultured in closed bioreactors and exposed to red, green, blue, or white LED lights. The illumination with red LED light resulted in the highest cell growth and highest cell densities compared to all other light sources (order of cell densities: red > white > green > blue LED light). In contrast, the highest phycocyanin concentrations were found when AP was cultured under blue LED light (e.g., order of concentrations: blue > white > red > green LED light). LED-blue light stimulated the accumulation of nitrogen compounds in the form of phycobiliproteins at the expense of cell growth. The results of the study revealed that exposure to different LED light colors can improve the quality and quantity of the biomass gained in AP cultures. Full article
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Article
Modeling and Optimizing the Effect of Light Color, Sodium Chloride and Glucose Concentration on Biomass Production and the Quality of Arthrospira platensis Using Response Surface Methodology (RSM)
Life 2022, 12(3), 371; https://doi.org/10.3390/life12030371 - 03 Mar 2022
Cited by 2 | Viewed by 787
Abstract
Arthrospira platensis (Spirulina) biomass is a valuable source of sustainable proteins, and the basis for new food and feed products. State-of-the-art production of Spirulina biomass in open pond systems only allows limited control of essential process parameters, such as light color, [...] Read more.
Arthrospira platensis (Spirulina) biomass is a valuable source of sustainable proteins, and the basis for new food and feed products. State-of-the-art production of Spirulina biomass in open pond systems only allows limited control of essential process parameters, such as light color, salinity control, or mixotrophic growth, due to the high risk of contaminations. Closed photobioreactors offer a highly controllable system to optimize all process parameters affecting Spirulina biomass production (quantity) and biomass composition (quality). However, a comprehensive analysis of the impact of light color, salinity effects, and mixotrophic growth modes of Spirulina biomass production has not been performed yet. In this study, Response Surface Methodology (RSM) was employed to develop statistical models, and define optimal mixotrophic process conditions yielding maximum quantitative biomass productivity and high-quality biomass composition related to cellular protein and phycocyanin content. The individual and interaction effects of 0, 5, 15, and 30 g/L of sodium chloride (S), and 0, 1.5, 2, and 2.5 g/L of glucose (G) in three costume-made LED panels (L) where the dominant color was white (W), red (R), and yellow (Y) were investigated in a full factorial design. Spirulina was cultivated in 200 mL cell culture flasks in different treatments, and data were collected at the end of the log growth phase. The lack-of-fit test showed that the cubic model was the most suitable to predict the biomass concentration and protein content, and the two-factor interaction (2FI) was preferred to predict the cellular phycocyanin content (p > 0.05). The reduced models were produced by excluding insignificant terms (p > 0.05). The experimental validation of the RSM optimization showed that the highest biomass concentration (1.09, 1.08, and 0.85 g/L), with improved phycocyanin content of 82.27, 59.47, 107 mg/g, and protein content of 46.18, 39.76, 53.16%, was obtained under the process parameter configuration WL4.28S2.5G, RL10.63S1.33G, and YL1.00S0.88G, respectively. Full article
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Article
Silver Nanoparticle Production by the Cyanobacterium Cyanothece sp.: De Novo Manipulation of Nano-Biosynthesis by Phytohormones
Life 2022, 12(2), 139; https://doi.org/10.3390/life12020139 - 18 Jan 2022
Viewed by 498
Abstract
Background: Numerous cyanobacteria have the potential to reduce metallic ions to form pure metal nanoparticles in a green biosynthesis process. Aim: To investigate the production capacity of silver nanoparticles by the cyanobacterium Cyanothece sp. and to examine the effect of five different phytohormones, [...] Read more.
Background: Numerous cyanobacteria have the potential to reduce metallic ions to form pure metal nanoparticles in a green biosynthesis process. Aim: To investigate the production capacity of silver nanoparticles by the cyanobacterium Cyanothece sp. and to examine the effect of five different phytohormones, indole acetic acid, kinetin; gibberellic acid; abscisic acid; and methyl jasmonate, on this capacity. Methods: The cyanobacterial strain was grown for 60 days and the harvested cyanobacterium biomass was incubated with 0.1 mM of AgNO3. Percentage conversion of Ag+ to Ag0 was calculated to indicate the AgNPs’ production capacity. Different concentrations of the five phytohormones were added to cultures and the AgNP production was monitored throughout different time intervals. Results: Cyanothece sp. biosynthesized spherical AgNPs (diameter range 70 to 140 nm, average diameter 84.37 nm). The addition of indole acetic acid and kinetin provoked the maximum conversion (87.29% and 55.16%, respectively) of Ag+ to Ag0, exceeding or slightly below that of the control (56%). Gibberellic and abscisic acids failed to elevate the Ag+ to Ag0 conversion rate (45.23% and 47.95%, respectively) above that of the control. Methyl jasmonate increased the Ag+ to Ag0 conversion rate to 90.29%, although nearly all the cyanobacterial cultures died at the end. Conclusion: Phytohormones could be used to induce or inhibit the green production of AgNPs with the cyanobacterium Cyanothece sp. This novel manipulation technique may have several applications in agriculture or biomedicine. Full article
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Article
Bioremediation of Per- and Poly-Fluoroalkyl Substances (PFAS) by Synechocystis sp. PCC 6803: A Chassis for a Synthetic Biology Approach
Life 2021, 11(12), 1300; https://doi.org/10.3390/life11121300 - 26 Nov 2021
Viewed by 940
Abstract
One of the main concerns in industrialized countries is represented by per- and poly-fluoroalkyl substances (PFAS), persistent contaminants hardly to be dealt with by conventional wastewater treatment processes. Phyco-remediation was proposed as a green alternative method to treat wastewater. Synechocystis sp. PCC6803 is [...] Read more.
One of the main concerns in industrialized countries is represented by per- and poly-fluoroalkyl substances (PFAS), persistent contaminants hardly to be dealt with by conventional wastewater treatment processes. Phyco-remediation was proposed as a green alternative method to treat wastewater. Synechocystis sp. PCC6803 is a unicellular photosynthetic organism candidate for bioremediation approaches based on synthetic biology, as it is able to survive in a wide range of polluted waters. In this work, we assessed the possibility of applying Synechocystis in PFAS-enriched waters, which was never reported in the previous literature. Respirometry was applied to evaluate short-term toxicity of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), which did not affect growth up to 0.5 and 4 mg L−1, respectively. Continuous and batch systems were used to assess the long-term effects, and no toxicity was highlighted for both compounds at quite high concentration (1 mg L−1). A partial removal was observed for PFOS and PFOA, (88% and 37%, with removal rates of about 0.15 and 0.36 mg L−1 d−1, respectively). Measurements in fractionated biomass suggested a role for Synechocystis in the sequestration of PFAS: PFOS is mainly internalized in the cell, while PFOA is somehow transformed by still unknown pathways. A preliminary bioinformatic search gave hints on transporters and enzymes possibly involved in such sequestration/transformation processes, opening the route to metabolic engineering in the perspective application of this cyanobacterium as a new phyco-remediation tool, based on synthetic biology. Full article
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Article
Characterization of an Aerosol-Based Photobioreactor for Cultivation of Phototrophic Biofilms
Life 2021, 11(10), 1046; https://doi.org/10.3390/life11101046 - 05 Oct 2021
Cited by 2 | Viewed by 694
Abstract
Phototrophic biofilms, in particular terrestrial cyanobacteria, offer a variety of biotechnologically interesting products such as natural dyes, antibiotics or dietary supplements. However, phototrophic biofilms are difficult to cultivate in submerged bioreactors. A new generation of biofilm photobioreactors imitates the natural habitat resulting in [...] Read more.
Phototrophic biofilms, in particular terrestrial cyanobacteria, offer a variety of biotechnologically interesting products such as natural dyes, antibiotics or dietary supplements. However, phototrophic biofilms are difficult to cultivate in submerged bioreactors. A new generation of biofilm photobioreactors imitates the natural habitat resulting in higher productivity. In this work, an aerosol-based photobioreactor is presented that was characterized for the cultivation of phototrophic biofilms. Experiments and simulation of aerosol distribution showed a uniform aerosol supply to biofilms. Compared to previous prototypes, the growth of the terrestrial cyanobacterium Nostoc sp. could be almost tripled. Different surfaces for biofilm growth were investigated regarding hydrophobicity, contact angle, light- and temperature distribution. Further, the results were successfully simulated. Finally, the growth of Nostoc sp. was investigated on different surfaces and the biofilm thickness was measured noninvasively using optical coherence tomography. It could be shown that the cultivation surface had no influence on biomass production, but did affect biofilm thickness. Full article
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Review

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Review
Strain Development in Microalgal Biotechnology—Random Mutagenesis Techniques
Life 2022, 12(7), 961; https://doi.org/10.3390/life12070961 - 27 Jun 2022
Viewed by 540
Abstract
Microalgal biomass and metabolites can be used as a renewable source of nutrition, pharmaceuticals and energy to maintain or improve the quality of human life. Microalgae’s high volumetric productivity and low impact on the environment make them a promising raw material in terms [...] Read more.
Microalgal biomass and metabolites can be used as a renewable source of nutrition, pharmaceuticals and energy to maintain or improve the quality of human life. Microalgae’s high volumetric productivity and low impact on the environment make them a promising raw material in terms of both ecology and economics. To optimize biotechnological processes with microalgae, improving the productivity and robustness of the cell factories is a major step towards economically viable bioprocesses. This review provides an overview of random mutagenesis techniques that are applied to microalgal cell factories, with a particular focus on physical and chemical mutagens, mutagenesis conditions and mutant characteristics. Full article
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Review
The Beneficial Effects of Cyanobacterial Co-Culture on Plant Growth
Life 2022, 12(2), 223; https://doi.org/10.3390/life12020223 - 31 Jan 2022
Cited by 1 | Viewed by 1111
Abstract
Cyanobacteria are ubiquitous phototrophic prokaryotes that find a wide range of applications in industry due to their broad product spectrum. In this context, the application of cyanobacteria as biofertilizers and thus as an alternative to artificial fertilizers has emerged in recent decades. The [...] Read more.
Cyanobacteria are ubiquitous phototrophic prokaryotes that find a wide range of applications in industry due to their broad product spectrum. In this context, the application of cyanobacteria as biofertilizers and thus as an alternative to artificial fertilizers has emerged in recent decades. The benefit is mostly based on the ability of cyanobacteria to fix elemental nitrogen and make it available to the plants in a usable form. However, the positive effects of co-cultivating plants with cyanobacteria are not limited to the provision of nitrogen. Cyanobacteria produce numerous secondary metabolites that can be useful for plants, for example, they can have growth-promoting effects or increase resistance to plant diseases. The effects of biotic and abiotic stress can as well be reduced by many secondary metabolites. Furthermore, the biofilms formed by the cyanobacteria can lead to improved soil conditions, such as increased water retention capacity. To exchange the substances mentioned, cyanobacteria form symbioses with plants, whereby the strength of the symbiosis depends on both partners, and not every plant can form symbiosis with every cyanobacterium. Not only the plants in symbiosis benefit from the cyanobacteria, but also vice versa. This review summarizes the beneficial effects of cyanobacterial co-cultivation on plants, highlighting the substances exchanged and the strength of cyanobacterial symbioses with plants. A detailed explanation of the mechanism of nitrogen fixation in cyanobacterial heterocysts is given. Finally, a summary of possible applications of co-cultivation in the (agrar-)industry is given. Full article
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