To explore a new and simple rapid extraction and purification technique for phycocyanin, an ionic liquids(ILs)-based aqueous two-phase system(ATPS) was developed for the purification of phycocyanin from Spirulina extracts. Effects of various process parameters such as the concentrations of [Bmim]Cl, the concentrations of KH 2 PO 4 , the concentrations of crude phycocyanin, the system pH and the temperature on partitioning of phycocyanin were evaluated. The obtained data indicated that phycocyanin was preferentially partitioned into the ILs-rich phase and the ATPS composed of 23% (w/w) [Bmim]Cland 29% (w/w) KH 2 PO 4 at 30°C and pH 7.0 showed good selectivity on phycocyanin. Under the optimum conditions, phycocyanin with a purity of 3.98 and yield of about 90.23 % was obtained. Therefore, ILs-based ATPS was an effective method for partitioning and recovery of phycocyanin from Spirulina extracts.
The optimization of the reverse micelles extraction of protein from grape seeds was carried out using response surface methodology (RSM). Based on the Plackett-Burman design and steepest ascent, CTAB concentration, pH, NaCl concentration and crude protein concentration were selected as the most extract conditions. Subsequently, the optimum combination of the selected factors was investigated by the Box-Behnken design. The final condition of extraction optimized with RSM was CTAB concentration 39 mmol/L, pH 5.6, NaCl concentration 0.01 mol/L, and crude protein concentration 2.1 mg/mL. The forward extraction yield of 82.3% in triplicate under optimal extraction condition was obtained.
Microalgae have received significant attention as potential next-generation microbiologic cell factories for biofuels. However, the production of microalgal biofuels is not yet sufficiently cost-effective for commercial applications. To screen higher lipid-producing strains, heavy carbon ion beams are applied to induce a genetic mutant. An RNA-seq technology is used to identify the pathways and genes of importance related to photosynthesis and biofuel production. The deep elucidation of photosynthesis and the fatty acid metabolism pathway involved in lipid yield is valuable information for further optimization studies. This study provided the photosynthetic efficiency and transcriptome profiling of a unicellular microalgae, Scenedesmus obliqnus mutant SO120G, with enhanced lipid production induced by heavy carbon ion beams. The lipid yield (52.5 mg L−1) of SO120G mutant were enhanced 2.4 fold compared with that of the wild strain under the nitrogen deficient condition. In addition, the biomass and growth rate were 57% and 25% higher, respectively, in SO120G than in the wild type, likely owing to an improved maximum quantum efficiency (Fv/Fm) of photosynthesis. As for the major pigment compositions, the content of chlorophyll a and carotenoids was higher in SO120G than in the wild type. The transcriptome data confirmed that a total of 2077 genes with a change of at least twofold were recognized as differential expression genes (DEGs), of which 1060 genes were up-regulated and 1017 genes were down-regulated. Most of the DEGs involved in lipid biosynthesis were up-regulated with the mutant SO120G. The expression of the gene involved in the fatty acid biosynthesis and photosynthesis of SO120G was upregulated, while that related to starch metabolism decreased compared with that of the wild strain. This work demonstrated that heavy-ion irradiation is an promising strategy for quality improvement. In addition, the mutant SO120G was shown to be a potential algal strain for enhanced lipid production. Transcriptome sequencing and annotation of the mutant suggested the possible genes responsible for lipid biosynthesis and photosynthesis, and identified the putative target genes for future genetic manipulation and biotechnological applications.
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