Changes in photosynthetic pigment and protein contents, growth and the spectral characteristics in Chlorella vulgaris in response to selenium stress were investigated. Carotenoids (β-carotene and xanthophylls) and chlorophyll (Chl a and Chl b) contents in cells exposed to Se 50mg/L increased primarily and decreased afterwards, while photosynthetic pigments in cells exposed to Se 800mg/L decreased significantly. Chlorophyll (Chl) absorption peak at 693nm and prominent Chl emission peak at 700 nm, weakened significantly after Se stress. The excitation spectra showed a decrease in excitation energy transfer efficiency in Se-stressed cells. Total soluble protein decreased after Se stress. The changes in total Se, Mg2+, Ca2+, K+and Na+ concentrations in culture medium and cells were also determined by ICP-AES.

Accumulation of Se in mixotrophic culture of Spirulina platensis was investigated in this study. Results indicated that glucose was better than acetate as an organic carbon source for mixotrophic culture of S. platensis. Supplementation of glucose (2gL-1) significantly enhanced the biomass concentration (2.57gL-1) and the production of phycocyanin (0.279gL-1)-and-allophycocyanin-(0.126gL-1) in S. platensis, which were much higher than those of photoautotrophic culture (1.08gL-1,0.119g-L-1and0.042g-L-1,respectively). Stepwise addition of Se during the growth phase avoided the inhibitory effect of high Se concentration on the growth of S. platensis. The Se enrichment favored the production of phycocyanin and allophycocyanin in the algal cells. The highest Se yield (1033 lgL-1) was obtained at an accumulative Se concentration of 250mgL-1, with organic Se percentage, biomass concentration, phycocyanin and allophycocyanin yields of 92.3%, 2.55gL-1, 0.295gL-1and 0.153gL-1, respectively. These results indicated that the application of mixotrophic culture S. platensis with stepwise addition of Se to the medium could offer an effective and economical way for the production of high Se enriched algal products.

The feasibility of mixotrophic culture of high selenium-enriched Spirulina platensis was investigated in this study. The results indicated that supplementation of acetate to the mixotrophic culture of S. platensis led to a significant enhancement in biomass concentration, chlorophyll α, lutein, β-carotene, phycocyanin and allophycocyanin production when compared to the photoautotrophic culture. Stepwise addition of selenium (Se) source during the exponential growth phase of S. platensis can avoid the inhibitory effect of high Se concentration on cell growth. At an accumulative Se concentration of 450mgL−1 undermixotrophic culture conditions, the highest Se yield was obtained; while significant enhancement in Se accumulation capability, algal biomass concentration and photosynthetic pigment yield was also observed. These results indicated that the application of mixotrophic culture with stepwise addition of Se to culture of S. platensis offers a more effective and economical way for the production of high Se-enriched biological compounds.

用激光散射(LLS)及透射电镜(TEM)技术研究了Te (IV)-I--RhB水溶液中液相纳米粒子在自然状态下的聚集行为及粒径分布，并用共振瑞利散射光谱、荧光发射光谱、紫外-可见光谱对该液相纳米体系的光谱性质进行了表征.结果表明：在0.8 mol/ L HCL介质中，当 Te (IV)浓度为 4、8、12、16、20μg/ L时，Te (IV)-I--RhB 体系平均粒径分别为 192、228、262、278、300 nm；纳米粒子的形成及其聚合行为导致 RhB在558 nm处的吸收峰(A558)的减色效应及 598 nm处的发射峰(F598)的荧光猝灭和623 nm处的共振散射峰(I623)增强，并与 Te(IV)浓度呈良好的线性关系；体系在623 nm处的散射强度 I1/ 3与其粒径成正比。用等离子体原子发射光谱( ICP)、元素分析( EA)等手段对该纳米粒子进行表征，确定了其最简分子式为(RhB)4(TeI8)。

A fast protein liquid chromatographic method for purification of selenium-containing phycocyanin (Se-PC) from selenium-enriched Spirulina platensis was described in this study. The purification procedures involved fractionation by ammonium sulfate precipitation, DEAE-Sepharose ion-exchange chromatography and Sephacry S-300 size exclusion chromatography. The purity ratio (A620/A280) and the separation factor (A620/A655) of the purified Se-PC were 5.12 and 7.92, respectively. The Se concentration of purified Se-PC was 496.5 ugg-1 protein, as determined by ICP-AES analysis. The purity of the Se-PC was further characterized by UV-VIS and fluorescence spectrometry, SDS-PAGE, RP-HPLC and gel filtration HPLC. The apparent molecular mass of the native Se-PC determined by gel filtration HPLC was 109 kDa, indicating that the protein existed as a trimer. SDS-PAGE of the purified Se-PC yielded two major bands corresponding to the a and b subunits. A better separation of these two subunits was obtained by RP-HPLC. Identification of the a and b subunits separated by SDS-PAGE and RP-HPLC was achieved by peptide mass fingerprinting (PMF) using MALDI-TOF-TOF mass spectrometry.