Time-resolved metabolomics of a novel trebouxiophycean alga using (13)CO2 feeding.

Oil-rich algae are potentially promising as next-generation biofuel feedstock. However, the productivity of oil needs to be improved for industrial use. The biosynthesis of oil and its control mechanism have not been characterized in any algae, and understanding the metabolic network is vital to achieve the precise engineering of algae metabolic pathways.

Metabolic and morphological changes of an oil accumulating trebouxiophycean alga in nitrogen-deficient conditions.

Oil-rich algae have promising potential for a next-generation biofuel feedstock. MBIC 11204, a novel unicellular green algal strain, accumulates a large amount of oil (lipids) in nitrogen-deficient (-N) conditions. Although the oil bodies are easily visualized by lipophilic staining in the cells, little is known about how oil bodies are metabolically synthesized.

Genetic transformation of Pseudochoricystis ellipsoidea, an aliphatic hydrocarbon-producing green alga.

Pseudochoricystis ellipsoidea is a recently isolated unicellular green alga, which is classified within the family Trebouxiophyceae. This alga has a unique ability to synthesize and accumulate intracellularly a significant amount of aliphatic hydrocarbons. To elucidate molecular mechanisms of the hydrocarbon production in this organism, the development of genetic methods including DNA transformation methods are important.

Molecular cloning of a Pinguiochrysis pyriformis oleate-specific microsomal Δ12-fatty acid desaturase and functional analysis in yeasts and thraustochytrids.

We isolated a putative desaturase gene from a marine alga, Pinguiochrysis pyriformis MBIC 10872, which is capable of accumulating eicosapentaenoic acid (C20:5(Δ5,8,11,14,17)). The gene possessed an open reading frame of 1,314 bp encoding a putative 437 amino acid residues showing high sequence identity (37-48%) with fungal and nematode Δ12-fatty acid desaturases. Yeast cells transformed with the gene converted endogenous oleic acid (C18:1(Δ9)) to linoleic acid (C18:2(Δ9,12)).

Selection of microalgal growth model for describing specific growth rate-light response using extended information criterion.

The effects of light intensity and carbon dioxide (CO2) concentration on the growth of the highly CO2-tolerant green alga Chlorococcum littorale were studied in batch cultures. Four mathematical representations were compared for the specific growth rate-light response curve: a rectangular hyperbolic function, Steele's exponential function, a Poisson function and a hyperbolic tangent function. The hyperbolic tangent function, which is commonly used for representing the photosynthesis-light relationship, gave the best fit as evaluated by the extended information criterion (EIC).

Evaluation of the sensitivity of marine microalgal strains to the heavy metals, Cu, As, Sb, Pb and Cd.

The sensitivity of nine marine microalgal species (consisting of five divisions and seven genera) to the five heavy metals, Cu(II), As(V), Sb(III), Pb(II) and Cd(II) was studied by using a fluorometric growth-inhibition assay with 96-well microplates. The algal strains studied were Cylindrotheca sp. and the LPP group that respectively characterize aggregating and filamentous types, and Chlorococcum littorale, Chlorococcum sp.

Some Cyanobacteria synthesize semi-amylopectin type alpha-polyglucans instead of glycogen.

It is widely accepted that green plants evolved the capacity to synthesize the highly organized branched alpha-polyglucan amylopectin with tandem-cluster structure, whereas animals and bacteria continued to produce random branched glycogen. Although most previous studies documented that cyanobacteria accumulate glycogen, the present study shows explicitly that some cyanobacteria such as Cyanobacterium sp. MBIC10216, Myxosarcina burmensis and Synechococcus sp.

Effects of chloramphenicol on photosynthesis, protein profiles and transketolase activity under extremely high CO2 concentration in an extremely-high-CO2-tolerant green microalga, Chlorococcum littorale.

An extremely-high-CO2-tolerant alga, Chlorococcum littorale, showed high quantum efficiency of PSII (PhiII) in the light at 40% CO2, as well as at 5% CO2. However, PhiII decreased greatly when chloramphenicol (CAP) was added at 40% CO2, while no such decrease was observed at 5% CO2. Cycloheximide showed no effect on PhiII at either 5% or 40% CO2.

Optimized aeration by carbon dioxide gas for microalgal production and mass transfer characterization in a vertical flat-plate photobioreactor.

To optimize the aeration conditions for microalgal biomass production in a vertical flat-plate photobioreactor (VFPP), the effect of the aeration rate on biomass productivity was investigated under given conditions. Air enriched with 5% or 10% (v/v) CO(2) was supplied for the investigation at rates of 0.025-1 vvm.

Regulation of energy balance in photosystems in response to changes in CO2 concentrations and light intensities during growth in extremely-high-CO2-tolerant green microalgae.

Regulation of energy balance in photosystems in response to extremely-high-CO2 (40%) and low-CO2 (0.04%) stress was studied in extremely-high-CO2-tolerant green microalgae, Chlorococcum littorale and Chlorella sp. UK001.