Inhibition of Polyphosphate Degradation in sp. PCC6803 through Inactivation of the Gene.

Phosphorus is an essential but non-renewable nutrient resource critical for agriculture. Luxury phosphorus uptake allows microalgae to synthesize polyphosphate and accumulate phosphorus, but, depending on the strain of algae, polyphosphate may be degraded within 4 hours of accumulation. We studied the recovery of phosphorus from wastewater through luxury uptake by an engineered strain of sp.

Improvement of Lutein and Zeaxanthin Production in sp. 247 by Optimizing Light Intensity and Culture Salinity Conditions.

In this study, we sought to improve lutein and zeaxanthin production in sp. 247 and investigated the effect of environmental factors on lutein and zeaxanthin productivity in sp. The basic medium selection and N:P ratio were adjusted to maximize cell growth in one-stage culture, and lutein and zeaxanthin production conditions were optimized using a central composite design for two-stage culture.

Different Regulatory Modes of sp. PCC 6803 in Response to Photosynthesis Inhibitory Conditions.

Cyanobacteria are promising industrial platforms owing to their ability to produce diverse natural secondary metabolites and nonnative value-added biochemicals from CO and light. To fully utilize their industrial potency, it is critical to understand their photosynthetic efficiency under various environmental conditions. In this study, we elucidated the inhibitory mechanisms of photosynthesis under high-light and low-temperature stress conditions in the model cyanobacterium sp.

Year-Round Cultivation of sp. for Essential Lipid Production in a Semi-Open Raceway System.

There is increasing demand for essential fatty acids (EFAs) from non-fish sources such as microalgae, which are considered a renewable and sustainable biomass. The open raceway system (ORS) is an affordable system for microalgae biomass cultivation for industrial applications. However, seasonal variations in weather can affect biomass productivity and the quality of microalgal biomass.

Multi-Omic Analyses Reveal Habitat Adaptation of Marine Cyanobacterium sp. PCC 7338.

Cyanobacteria are considered as promising microbial cell factories producing a wide array of bio-products. Among them, sp. PCC 7338 has the advantage of growing in seawater, rather than requiring arable land or freshwater.

Current Status and Future Strategies to Increase Secondary Metabolite Production from Cyanobacteria.

Cyanobacteria, given their ability to produce various secondary metabolites utilizing solar energy and carbon dioxide, are a potential platform for sustainable production of biochemicals. Until now, conventional metabolic engineering approaches have been applied to various cyanobacterial species for enhanced production of industrially valued compounds, including secondary metabolites and non-natural biochemicals. However, the shortage of understanding of cyanobacterial metabolic and regulatory networks for atmospheric carbon fixation to biochemical production and the lack of available engineering tools limit the potential of cyanobacteria for industrial applications.

New Surface Modification Method To Develop a PET-Based Membrane with Enhanced Ion Permeability and Organic Fouling Resistance for Efficient Production of Marine Microalgae.

This paper presents a new surface modification strategy to develop a poly(ethylene terephthalate) (PET)-based membrane having a hydrophilic surface, high nutrient ion permeability, sufficient mechanical strength, and organic fouling resistance, using an anthracene (ANT)-attached polyethylene glycol (PEG) surface modification agent (SMA) synthesized in this work. During the modification process, the ANT parts of the SMAs poke through and anchor to the surface of a commercial PET woven fabric via physical interactions and mechanical locking. The PEG chain parts coat the surface in the brush and arch forms, which generates a hydration layer on the fabric surface.

Enhanced lipid productivity in AGP knockout marine microalga Tetraselmis sp. using a DNA-free CRISPR-Cas9 RNP method.

A marine green microalga, Tetraselmis sp., has been studied for the production of biomass and lipids in seawater culture. Since carbohydrate and lipid biosynthesis are competitive metabolic pathways, we attempted to increase lipid synthesis in Tetraselmis by inhibiting carbohydrate synthesis.

Isolation and genome analysis of Winogradskyella algicola sp. nov., the dominant bacterial species associated with the green alga Dunaliella tertiolecta.

Microalgae and bacteria are known to be closely associated in diverse environments. To isolate dominant bacterial species associated with a green alga, Dunaliella tertiolecta, a photoreactor culture of the microalga was investigated using culture-based and culture-independent approaches. The bacterial community structure of the algal culture showed that the most abundant bacterial species under the culture conditions was related to the genus Winogradskyella.

Phycobiliproteins Production Enhancement and Lipidomic Alteration by Titanium Dioxide Nanoparticles in Synechocystis sp. PCC 6803 Culture.

This study aimed to improve the production of phycobiliproteins using TiO nanoparticles (NPs) in Synechocystis sp. PCC 6803. The growth characteristics of Synechocystis cells were not affected by TiO NPs treatment, but this treatment increased the chlorophyll content significantly by 62.

Label-free non-invasive quantitative measurement of lipid contents in individual microalgal cells using refractive index tomography.

Microalgae are promising candidates for biofuel production due to their high lipid content. To facilitate utilization of the microalgae for biofuel, rapid quantification of the lipid contents in microalgae is necessary. However, conventional methods based on the chemical extraction of lipids require a time-consuming destructive extraction process.

Development of Carbon-Based Solid Acid Catalysts Using a Lipid-Extracted Alga, , for Esterification.

Novel carbon-based solid acid catalysts were synthesized through a sustainable route from lipid-extracted microalgal residue of , for biodiesel production. Two carbon-based solid acid catalysts were prepared by surface modification of bio-char with sulfuric acid (H₂SO₄) and sulfuryl chloride (SO₂Cl₂), respectively. The treated catalysts were characterized and their catalytic activities were evaluated by esterification of oleic acid.

Enzyme/whole-cell biotransformation of plant oils, yeast derived oils, and microalgae fatty acid methyl esters into n-nonanoic acid, 9-hydroxynonanoic acid, and 1,9-nonanedioic acid.

Oils and fatty acids are important renewable resources provided by nature. Therefore, biotransformation of renewable oils and fatty acids into industrially relevant C9 chemicals was investigated in this study. Olive oil, soybean oil, yeast derived oil, and microalgae fatty acid methyl esters were converted into n-nonanoic acid, 9-hydroxynonanoic acid, and 1,9-nonanedioic acid by a lipase and a recombinant Escherichia coli expressing oleate hydratase, long chain secondary alcohol dehydrogenase, Baeyer-Villiger monooxygenase, long chain primary alcohol dehydrogenase, and aldehyde dehydrogenase.

Enhanced Production of Fatty Acids via Redirection of Carbon Flux in Marine Microalga sp.

Lipids in microalgae are energy-rich compounds and considered as an attractive feedstock for biodiesel production. To redirect carbon flux from competing pathways to the fatty acid synthesis pathway of sp., we used three types of chemical inhibitors that can block the starch synthesis pathway or photorespiration, under nitrogen-sufficient and nitrogen-deficient conditions.

A general reaction network and kinetic model of the hydrothermal liquefaction of microalgae Tetraselmis sp.

In this work, the hydrothermal liquefaction (HTL) of microalgal Tetraselmis sp. was conducted at various reaction temperatures (250-350°C) and reaction times (10-60min). A general reaction network and a quantitative kinetic model were proposed for the HTL of microalgae.

Genome-wide transcriptome analysis revealed organelle specific responses to temperature variations in algae.

Temperature is a critical environmental factor that affects microalgal growth. However, microalgal coping mechanisms for temperature variations are unclear. Here, we determined changes in transcriptome, total carbohydrate, total fatty acid methyl ester, and fatty acid composition of Tetraselmis sp.

Theoretical Calculations on the Feasibility of Microalgal Biofuels: Utilization of Marine Resources Could Help Realizing the Potential of Microalgae.

Microalgae have long been considered as one of most promising feedstocks with better characteristics for biofuels production over conventional energy crops. There have been a wide range of estimations on the feasibility of microalgal biofuels based on various productivity assumptions and data from different scales. The theoretical maximum algal biofuel productivity, however, can be calculated by the amount of solar irradiance and photosynthetic efficiency (PE), assuming other conditions are within the optimal range.

Effect of Ethephon as an Ethylene-Releasing Compound on the Metabolic Profile of Chlorella vulgaris.

In this study, Chlorella vulgaris (C. vulgaris) was treated with ethephon at low (50 μM) and high (200 μM) concentrations in medium and harvested at 0, 7, and 14 days, respectively. The presence of ethephon led to significant metabolic changes in C.

Enhancing Photon Utilization Efficiency for Astaxanthin Production from Haematococcus lacustris Using a Split-Column Photobioreactor.

A split-column photobioreactor (SC-PBR), consisting of two bubble columns with different sizes, was developed to enhance the photon utilization efficiency in an astaxanthin production process from Haematococcus lacustris. Among the two columns, only the smaller column of SC-PBR was illuminated. Astaxanthin productivities and photon efficiencies of the SC-PBRs were compared with a standard bubble-column PBR (BC-PBR).

Seasonal Assessment of Biomass and Fatty Acid Productivity by Tetraselmis sp. in the Ocean Using Semi-Permeable Membrane Photobioreactors.

A green microalga, Tetraselmis sp., was cultivated in the coastal seawater of Young-Heung Island using semi-permeable membrane photobioreactors (SPM-PBRs) in different seasons. The microalgae in the SPM-PBRs were able to grow on nutrients diffused into the PBRs from the surrounding seawater through SPMs.

Specific light uptake rates can enhance astaxanthin productivity in Haematococcus lacustris.

Lumostatic operation was applied for efficient astaxanthin production in autotrophic Haematococcus lacustris cultures using 0.4-L bubble column photobioreactors. The lumostatic operation in this study was performed with three different specific light uptake rates (q(e)) based on cell concentration, cell projection area, and fresh weight as one-, two- and three-dimensional characteristics values, respectively.

Development of a floating photobioreactor with internal partitions for efficient utilization of ocean wave into improved mass transfer and algal culture mixing.

Culturing microalgae in the ocean has potentials that may reduce the production cost and provide an option for an economic biofuel production from microalgae. The ocean holds great potentials for mass microalgal cultivation with its high specific heat, mixing energy from waves, and large cultivable area. Suitable photobioreactors (PBRs) that are capable of integrating marine energy into the culture systems need to be developed for the successful ocean cultivation.

Elucidation of the growth delimitation of Dunaliella tertiolecta under nitrogen stress by integrating transcriptome and peptidome analysis.

Dunaliella tertiolecta LB 999 is an oleaginous microalgae species that produces large quantities of lipid and starch during nitrogen starvation; however, nitrogen starvation also limits the cell growth. In order to understand the underlying mechanisms of this phenomenon, the transcriptome and peptidome of D. tertiolecta LB 999 grown under different nitrogen and light conditions were analyzed.