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Microalgae exhibit great potential for biomass production. Although microalgae display an enormous biodiversity, surprisingly only 15 species are used for large scale production processes worldwide. The implementation of new production strains with good process-oriented properties, especially fast growth rate and heat resistance, could improve production efficiency and reduce costs. In this study 130 environmental samples collected in Germany, Spain, Italy and Portugal were investigated for fast growing thermotolerant photosynthetic species. Isolates were characterized and identified on a molecular level. In total 21 of the isolated freshwater strains were able to grow at 40 °C. Additionally, 13 of those 21 strains are able to grow at 45 °C. The highest growth rate at room temperature was 1.16 per day (isolate T306A), compared to 0.053 per day at 45 °C (isolate Sp13). In three thermotolerant strains pigment production was induced. Molecular identification by 18S rDNA sequencing revealed that the isolates were all chlorophytes belonging to four different families.

BACKGROUND: Complex polysaccharides are important in the pharmaceutical industry, yet, due to their large molecular weight and reduced charges, their purification is a highly demanding process that requires binding matrices with unique properties. This work demonstrates for the first time that complex polysaccharides biosynthesized by microalga Porphyridium purpureum can be adsorbed onto Q fibrous anion exchangers. RESULTSWhen the polysaccharides were characterized, the extent of sulfation was higher in native polysaccharides than in ethanol-or alkali-extracts. The zeta potentials increased with increasing pH and the highest charge was observed at pH 8, while the Z-average diameters of the polysaccharide at pH 6 were highest for alkali-extracts. Instead of pellicular resins, Q fibrous adsorbents were used to determine Langmuir thermodynamic properties and dynamic binding capacities. The parameters included static binding capacity and dissociation constant of 13.47 ± 1.02 mg g -1 and 0.141 ± 0.027 mg mL -1 , and 10 and 50% breakthrough capacities of 4.46 ± 0.22 and 5.51 ± 0.28 mg g -1 , respectively. The antiviral activity of the polysaccharides was demonstrated by minimizing bacteriophage lysis of Streptococcus thermophilus.CONCLUSION This work demonstrates that polysaccharide extraction can be optimized and the adsorption and desorption of a complex polysaccharide onto Q fibrous matrix is feasible. These parameters could be exploited for up-scaling of polysaccharides for nutraceutical and pharmaceutical applications. Primary recovery operations of sulfated polysaccharidesMicroalgae were pelleted by centrifugation at 3250 g and 4 • C for 45 min followed by addition of three parts of cold 99% ethanol to the microalgal supernatant. Likewise, polysaccharides were alkali extracted following the protocol of Miyajima and co-workers. 19 Both mixtures were shaken at 100 rpm for 10 min then kept at 4 • C for overnight extraction. The precipitates were separated from the aqueous phases by centrifugation as mentioned above. Pellets were resuspended in demineralized water, dialyzed through Spectra/Por regenerated cellulose membranes (MWCO, 12-14 kDa) overnight against double deionized water followed by lyophilization using an ALPHA 1-2 LD Plus (Martin Christ Gefriertrocknungsanlagen GmbH, Osterode am Harz, Germany). The ethanol-and alkali-extracted polysaccharides were designated 'Extract 1' and 'Extract 2', respectively.Determination of zeta potential and Z-average diameter of sulfated polysaccharide by light scattering P. purpureum polysaccharides were dissolved in 20 mmol L -1 citrate-phosphate buffer at pH 4, 5, 6, 7 and 8 to a concentration wileyonlinelibrary.com/jctb