Metataxonomy and pigments analyses unravel microbial diversity and the relevance of retinal-based photoheterotrophy at different salinities in the Odiel Salterns (SW, Spain).

Salinity has a strong influence on microorganisms distribution patterns and consequently on the relevance of photoheterotrophic metabolism, which since the discovery of proteorhodopsins is considered the main contributor to solar energy capture on the surface of the oceans. Solar salterns constitute an exceptional system for the simultaneous study of several salt concentrations, ranging from seawater, the most abundant environment on Earth, to saturated brine, one of the most extreme, which has been scarcely studied. In this study, pigment composition across the salinity gradient has been analyzed by spectrophotometry and RP-HPLC, and the influence of salinity on microbial diversity of the three domains of life has been evaluated by a metataxonomic study targeting hypervariable regions of 16S and 18S rRNA genes.

Up-Regulation of the Nrf2/HO-1 Antioxidant Pathway in Macrophages by an Extract from a New Halophilic Archaea Isolated in Odiel Saltworks.

The production of reactive oxygen species (ROS) plays an important role in the progression of many inflammatory diseases. The search for antioxidants with the ability for scavenging free radicals from the body cells that reduce oxidative damage is essential to prevent and treat these pathologies. Haloarchaea are extremely halophilic microorganisms that inhabit hypersaline environments, such as saltworks or salt lakes, where they have to tolerate high salinity, and elevated ultraviolet (UV) and infrared radiations.

Enhanced wastewater bioremediation by a sulfur-based copolymer as scaffold for microalgae immobilization (AlgaPol).

In recent years, there has been an increasing concern related to the contamination of aqueous ecosystems by heavy metals, highlighting the need to improve the current techniques for remediation. This work intends to address the problem of removing heavy metals from waterbodies by combining two complementary methodologies: adsorption to a copolymer synthesized by inverse vulcanization of sulfur and vegetable oils and phytoremediation by the microalga Chlorella sorokiniana to enhance the metal adsorption. After studying the tolerance and growth of Chlorella sorokiniana in the presence of the copolymer, the adsorption of highly concentrated Cd (50 mg L) by the copolymer and microalgae on their own and the combined immobilized system (AlgaPol) was compared.

Exploring Nordic microalgae as a potential novel source of antioxidant and bioactive compounds.

Nordic microalgae are a group of photosynthetic organisms acclimated to growth at low temperature and in varying light conditions; the subarctic climate offers bright days with moderate temperatures during summer and cold and dark winter months. The robustness to these natural stress conditions makes the species interesting for large-scale cultivation in harsh environments and for the production of high-value compounds. The aim of this study was to explore the ability of nineteen species of Nordic microalgae to produce different bioactive compounds, such as carotenoids or polyphenols.

Simultaneous production of carotenoids and chemical building blocks precursors from chlorophyta microalgae.

Replacement of fossil fuels has to be accompanied by the incorporation of bio-based procedures for the production of fine chemicals. With this aim, the microalga Chlamydomonas reinhardtii was selected for its ability to accumulate starch, an environmentally-friendly alternative source of chemical building blocks, such as 5'-hydroxymethylfurfural or levulinic acid. The content of appreciated lipophilic coproducts was assessed in the selected microalga cultured at different nutritional conditions; and the parameters for the acidic hydrolysis of the algal biomass, obtained after pigments extraction, were optimized using a Central Composite Design.

Metabarcoding data of prokaryotes and eukaryotes inhabiting the phosphogypsum stockpiles on the salt marshes of Huelva (SW Spain).

Around 100 Mt of phosphogypsum (PG) of extreme acidity and with high concentrations of heavy metals and radionuclides have been deposited on the salt marshes of the Tinto River estuary in Huelva (SW Spain) for more than forty years. The microbial community able to thrive in these adverse conditions remains totally unknown, despite the fact that it can highly influence the biogeochemical cycle of the phosphogypsum components and include new species with biotechnological interest. High throughput sequencing of 16S/18S rRNA encoding genes is a potent tool to uncover the microbial diversity of extreme environments.

Exploring the microbial community inhabiting the phosphogypsum stacks of Huelva (SW SPAIN) by a high throughput 16S/18S rDNA sequencing approach.

Around 100 Mt of phosphogypsum (PG) have been deposited in large stacks on the salt marshes of the Tinto River estuary in Huelva (SW Spain), covering about 1000 ha. These stacks contain extremely acidic water (pH < 2) with high concentrations of pollutants which can cause emissions into their surroundings, generating important environmental concerns. Despite many chemical, geological or hydrological studies have been conducted to characterize the PG stacks of Huelva, the microbial community inhabiting this extreme environment remains unexplored.

Impact of heavy metals in the microalga Chlorella sorokiniana and assessment of its potential use in cadmium bioremediation.

The chlorophyte microalga Chlorella sorokiniana was tested for the bioremediation of heavy metals pollution. It was cultured with different concentrations of Cu, Cd, As (III) and As (V), showing a significant inhibition on its growth at concentrations of 500 µM Cu, 250 µM Cd, 750 µM AsO and 5 mM AsO or higher. Moreover, the consumption of ammonium was also studied, showing significant differences for concentrations higher than 1 mM of Cu and As (III), and 5 mM of As (V).

Biochemical Characterization of the Amylase Activity from the New Haloarchaeal Strain sp. HS Isolated in the Odiel Marshlands.

Alpha-amylases are a large family of α,1-4-endo-glycosyl hydrolases distributed in all kingdoms of life. The need for poly-extremotolerant amylases encouraged their search in extreme environments, where archaea become ideal candidates to provide new enzymes that are able to work in the harsh conditions demanded in many industrial applications. In this study, a collection of haloarchaea isolated from Odiel saltern ponds in the southwest of Spain was screened for their amylase activity.

Dataset for proteomic analysis of cells under cadmium stress.

Cadmium is one of the most hazardous heavy metal for aquatic environments and one of the most toxic contaminants for phytoplankton. This work provides the dataset associated with the research publication "Effect of cadmium in the microalga : a proteomic study" [1]. This dataset describes a proteomic approach, based on the sequential window acquisition of all theoretical fragment ion spectra mass spectrometry (SWATH-MS), derived from exposure of to 250 µM Cd for 40 h, showing the proteins that are up- or downregulated.

Antioxidant, Antimicrobial, and Bioactive Potential of Two New Haloarchaeal Strains Isolated from Odiel Salterns (Southwest Spain).

The need to survive in extreme environments has furnished haloarchaea with a series of components specially adapted to work in such conditions. The possible application of these molecules in the pharmaceutical and industrial fields has received increasing attention; however, many potential bioactivities of haloarchaea are still poorly explored. In this paper, we describe the isolation and identification of two new haloarchaeal strains from the saltern ponds located in the marshlands of the Odiel River, in the southwest of Spain, as well as the in vitro assessment of their antioxidant, antimicrobial, and bioactive properties.

Effect of cadmium in the microalga Chlorella sorokiniana: A proteomic study.

Cadmium is one of the most common heavy metals in contaminated aquatic environments and one of the most toxic contaminants for phytoplankton. Nevertheless, there are not enough studies focused on the effect of this metal in algae. Through a proteomic approach, this work shows how Cd can alter the growth, cell morphology and metabolism of the microalga Chlorella sorokiniana.

Validation of a New Multicistronic Plasmid for the Efficient and Stable Expression of Transgenes in Microalgae.

Low stability of transgenes and high variability of their expression levels among the obtained transformants are still pending challenges in the nuclear genetic transformation of microalgae. We have generated a new multicistronic microalgal expression plasmid, called Phyco69, to make easier the large phenotypic screening usually necessary for the selection of high-expression stable clones. This plasmid contains a polylinker region (PLK) where any gene of interest () can be inserted and get linked, through a short viral self-cleaving peptide to the amino terminus of the aminoglycoside 3'-phosphotransferase (APHVIII) from , which confers resistance to the antibiotic paromomycin.

The Bacterial Phytoene Desaturase-Encoding Gene () is an Efficient Selectable Marker for the Genetic Transformation of Eukaryotic Microalgae.

Genetic manipulation shows great promise to further boost the productivity of microalgae-based compounds. However, selection of microalgal transformants depends mainly on the use of antibiotics, which have raised concerns about their potential impacts on human health and the environment. We propose the use of a synthetic phytoene desaturase-encoding gene () as a selectable marker and the bleaching herbicide norflurazon as a selective agent for the genetic transformation of microalgae.

Using agro-industrial wastes for mixotrophic growth and lipids production by the green microalga Chlorella sorokiniana.

There has been growing interest in the use of microalgae for the production of biofuels, but production costs continue to be too high to compete with fossil fuel prices. One of the main limitations for photobioreactor productivity is light shielding, especially at high cell densities. The growth of the green microalga Chlorella sorokiniana, a robust industrial species, has been evaluated under different trophic conditions with traditional carbon sources, such as glucose and sucrose, and alternative low cost carbon sources, such as carob pod extract, industrial glycerol and acetate-rich oxidized wine waste lees.

Characterization of the Microbial Population Inhabiting a Solar Saltern Pond of the Odiel Marshlands (SW Spain).

The solar salterns located in the Odiel marshlands, in southwest Spain, are an excellent example of a hypersaline environment inhabited by microbial populations specialized in thriving under conditions of high salinity, which remains poorly explored. Traditional culture-dependent taxonomic studies have usually under-estimated the biodiversity in saline environments due to the difficulties that many of these species have to grow at laboratory conditions. Here we compare two molecular methods to profile the microbial population present in the Odiel saltern hypersaline water ponds (33% salinity).

Effect of selenate on viability and selenomethionine accumulation of Chlorella sorokiniana grown in batch culture.

The aim of this work was to study the effect of Se(+VI) on viability, cell morphology, and selenomethionine accumulation of the green alga Chlorella sorokiniana grown in batch cultures. Culture exposed to sublethal Se concentrations of 40 mg · L(-1) (212 μM) decreased growth rates for about 25% compared to control. A selenate EC50 value of 45 mg · L(-1) (238.

Efficiency of different heterologous promoters in the unicellular microalga Chlamydomonas reinhardtii.

Despite the biotechnological interest of microalgae, no robust and stable methods for genetic transformation of most microalgal strains exist. The scanty and disperse data about the efficiency of heterologous promoters in microalgae and the use of different transformation methods, DNA quantities and reporter genes in the existing studies makes very difficult a real comparison of their efficiency. Using Chlamydomonas reinhardtii as a host, we have evaluated the efficiency of the heterologous promoters of cauliflower mosaic virus 35S (CaMV 35S) and Agrobacterium nopaline synthase (NOS) genes.

Carotenoids as protective response against oxidative damage in Dunaliella bardawil.

In the present work the relation between carotenoids production and cell response mechanisms to oxidative damage was studied. High light intensity and nitrogen starvation, both conditions, which may increase the oxidative damage in microalgae, significantly increased total carotenoids content in Dunaliella bardawil, the effect of N-starvation being more noticeable when acting synergetically with light on carotenoid production. S-starvation stimulated carotenoids production as much as N-starvation.

Metal toxicity in Chlamydomonas reinhardtii. Effect on sulfate and nitrate assimilation.

Cadmium (Cd(2+)) or copper (Cu(2+)) ions are toxic for Chlamydomonas reinhardtii growth, at 300 microM, and the alga may accumulate about 0.90+/-0.02 and 0.

Microalgae mediated photoproduction of beta-carotene in aqueous-organic two phase systems.

Improving productivity is a usual requirement for most biotechnological processes, and the utilisation of two-phase aqueous organic systems has proved to be an effective way to improve the productivity of poorly water-soluble or toxic compounds. The high hydrophobicity of beta-carotene, which is highly demanded by the pharma and agrofood industry, makes it a good candidate for aqueous/organic biphasic photoproduction. In the present work we have investigated the viability of a two-phase system for the production of beta-carotene by the marine microalgae Dunaliella salina using decane as organic phase.

Inhibition of nitrate consumption by nitrite in entrapped Chlamydomonas reinhardtii cells.

Whereas in freely suspended cell cultures growing photoautotrophically under non-limiting carbon conditions nitrite and nitrate were simultaneously consumed after ammonium consumption was complete, in alginate-entrapped cell cultures a sequential consumption of nitrite (first) and nitrate was observed after ammonium had almost been fully removed. In this paper results are reported that show inhibition of nitrate consumption by nitrite in immobilized cells. However no inhibition of nitrate active transport was observed.