| Spirulina,a blue green alga,is a prokaryote.Chlorella,a single-celled green alga,is a eukaryote.Spirulina(S.maxima and S.platensis) and Chlorella(C.pyrenoidosa and C.vulgaris) are used in this paper to compare their different responses to tellurium,which is in the same group as selenium in the periodic table of elements.The physiological and biochemical characteristics of Spirulina and Chlorella,and the absorption and distribution of tellurium in those algae after the addition of tellurium are studied in this research.Some important results are as follows:1.Two species of Spirulina responded differently to the different tellurium dose(χTe) when Te(Ⅳ) was added on the first day of inoculation.At the low tellurium dose(χTe≤0.028,CTe≤2 mg·L-1) Te(Ⅳ) promoted the growth of S.platensis.However,no effect was observed on S.maxima.At high tellurium dose(for S.platensis,χTe≥4.4,CTe≥320 mg·L-1;for S.maxima,χTe≥11.5,CTe≥560 mg·L-1),both Spirulina died after the addition of tellurium.S.maxima can endure more Te(Ⅳ) than S.platensis by comparing their 96hEC50 and tellurium dose.2.Two species of Chlorella had the same responses to tellurium dose(χTe) when Te(Ⅳ) was added on the first day of inoculation.These responses,however,were totally different from Spirulina.At low tellurium dose(for C.pyrenoidosa,χTe≤0.33,CTe≤10 mg·L-1;for C.vulgaris,χTe≤0.20,CTe≤10 mg·L-1),there was no effect to the growth of Chlorella. But at high tellurium dose(for C.pyrenoidosa,χTe≥3.33,CTe≥100 mg·L-1;for C.vulgaris,χTe≥2.00,CTe≥100 mg·L-1),the growth of Chlorella was promoted instead of being stressed as with Spirulina.3.Te(Ⅳ) was added to Spirulina at the different stages of their growth.At the initial stage, Te(Ⅳ) was added on the 3rd to the 5th day after inoculation with the concentration of 650, 750,850 and 950 mg·L-1.The maximum tellurium dose on the 5th day was 1.91,2.14, 2.43 and 2.88 for different test sets.At the stable stage,Te(Ⅳ) was added on the 7th to the 9th day after inoculation with the concentration of 700,800,900 and 1000 mg·L-1,and the maximum tellurium dose on the 9th day was 0.90,0.99,1.14 and 1.26 respectively. Though the Te(Ⅳ) concentration of 1000 mg·L-1 is the maximum in its test sets,itsχTe is 1.26.This is smaller than the minimumχTe 1.91 in the initial stage test sets.When Te(Ⅳ) was added to Spirulina at the initial stage,the algae cells were in higher tellurium dose, and Te(Ⅳ) had toxicity to Spirulina.So the final biomass,the content of soluble protein, phycocyanin,allophycocyanin and pigments of Spirulina were all lower than that of the control group.While at the stable stage of Spirulina,Te(Ⅳ) was nutrient to Spirulina.So the protein and pigments of Spirulina were increased,and the activicty of GPX was also increased with the increase of tellurium dose.4.We set different Te dose(χTe) and keptχTe invariable during the growth of S.platensis and C.pyrenoidosa.It indicated that the growth of S.platensis was promoted and the content of protein and pigments were higher than that of the control group whenχTe was less than 0.2.However,its growth was stressed,the content of protein being decreased, and MDA was increased whenχTe was 0.4.This implied that atχTe≤0.2,Te was nutrient to S.platensis.But atχTe≥0.4,Te was toxic to it.The results for C.pyrenoidosa were complicated,and it was difficult to distinguish when Te was nutrient or toxic to C. pyrenoidosa.WhenχTe was 0.2,the biomass and content of soluble protein were the maximum,but the content of all the pigments reduced except chlorophyll a,which was close to that of control.5.The absorption and distribution of tellurium in the algae were affected by the different methods of adding tellurium.For S.platensis,when Te(Ⅳ) was added on the first day of inoculation andχTe was kept invariable,it was found that most of the Te(Ⅳ) was released from algal cells in the form of volatile Te,at about 86.7%～91.0%.The content of organic Te in S.platens& was not high,while the organic Te was higher in S.platensis when Te was added at the stable stage in S.platensis.For C.pyrenoidosa,the organic Te in it was about 80%when Te(Ⅳ) was added on the first day of inoculation andχTe was kept invariable.More Te(Ⅳ) could be transformed into volatile Te by C.pyrenoidosa at higher Te dose.The results indicated that both Spirulina and Chlorella were good biological carriers for Te(Ⅳ),and both of them could be used to restore tellurium pollution.6.The effects of Te to different algae were observed by different methods of spectra,and the results indicated that all the peaks didn't change their positions after the addtion of Te to S.platensis and C.vulgaris.For S.platensis,the UV-Vis spectrum demonstrated that more harm was done to phycocyanin and chlorophyll a at high Te dose than other pigments;the fluorescence spectra showed that the peak intensities reduced greatly at high Te dose.For C.vulgaris,the UV-Vis,fluorescence and FT-IR spectra didn't change significantly.Moreover,when Te dose was 0.4,the peak intensities were almost the highest.This was consistent with the results we got before,that is,at a certain amount of high Te dose,the growth of C.vulgaris was promoted.In conclusion,two different species of algae had different responses to Te.
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