THE TOXICITY OF TWO NEWLY-SYNTHESIZED COMPOUNDS ON SCENEDESMUS OBLIQUUS KǖTZ

LY-04 and WSQIF are newly-synthesized compounds which were presented by the Institute of Pesticides Chemistry, Central China Normal University. LY-04 belongs to α-oxophosphonic acid derivatives, while WSQIF is an aromatic acetyl oxophosphonic acid derivative. In this study, the toxicity of LY-04 and WSQIF on Scenedesmus obliquus Kütz was examined. The EC 50 of LY-04 and WSQIF were determined in S. obliquus cells at 24h, 48h, 72h, 96h represented by cell density. Our data showed that the 24h, 48h, 72h, 96h EC 50 of LY-04 were 1983mg/L, 2943mg/L, 240mg/L and 65.0mg/L acetone, respectively, and the 24h, 48h, 72h, 96h EC 50 of WSQIF were 15.9mg/L, 53.0mg/L, 98.0mg/L and 28.8mg/L respectively. LY-04 displayed a higher insecticidal activity, while WSQIF showed a higher phytocidal activity. As LY-04 and WSQIF were designed to act as insecticide and herbicide, respectively, the results were in contrast to the anticipated ones. According to the toxicant classification standard, EC 50 of both substances was far higher than 3mg/L, while the toxicity of LY-04 and WSQIF to aquatic algae were fairly low, indicating that these two pesticides are rather safe to the aquatic ecosystem.

Assessment of Biomass Productivities of Chlorella vulgaris and Scenedesmus obliquus in Defined Media and Municipal Wastewater at Varying Concentration of Nitrogen

Microalgae are emerging as one of the most promising long-term sustainable sources of renewable energy. Studies were conducted on two freshwater Chlorophytes, Chlorella vulgaris and Scenedesmus obliquus to evaluate heterotrophic growth rate and biomass productivity in filter-sterilized defined medium (BG 11) and municipal wastewater, both with varying concentrations of nitrogen (N). For each isolate, cultures were separately incubated in triplicate at room temperature with constant agitation on a shaker at 150 rpm for 9 days. In 0.25 mg N/L BG11 medium, the growth rate and biomass productivity of C. vulgaris were 0.28 day-1 and 3.5 g·L-1, respectively. In wastewater, the same amount of N addition resulted in a higher growth rate 0.44 day-1 and associated biomass productivity of 4.96 g·L-1. Increasing N levels to 0.5 mg N/L in BG11 caused an increase in growth rate (0.37 day-1) and biomass productivity (4.28 g·L-1), while the increase in N in wastewater caused growth to decline to 0.32 day-1 with decreased biomass productivity of 2.19 g·L-1. A further increase in N to 1.0 mg N/L in BG11 caused an increase in the growth rate (0.43 day-1) and a decrease in biomass productivity (3.64 g·L-1), while in wastewater, growth rate and productivity of C. vulgaris were 0.32 day-1 and 2.31 g·L-1, respectively. Overall, C. vulgaris grew faster and produced greater biomass than S. obliquus under comparable conditions. Based on high growth rate and biomass productivity of C. vulgaris, it could be a potential candidate for further consideration for simultaneous wastewater treatment and biofuel production.

Microalgal Cultivation in Secondary Effluents:Enhancement of Algal Biomass,Nutrient Removal,and Lipid Productivity

The growth performance,nutrient removal,lipid accumulation and morphological changes of Cyanobacterium aponinum OUC1 and Scenedesmus obliquus which were cultured in secondary effluents from two wastewater treatment plants:Tuandao Wastewater Treatment Plant(ETD)and Licun River Wastewater Treatment Plant(ELR)were investigated.The results showed that both C.aponinum OUC1 and S.obliquus have superior growth performances in both undiluted effluents,while the better of them was that in ETD effluent,with cell densities of C.aponinum OUC1 and S.obliquus increased by 159%and 66%over that of BG11(control),respectively.Regarding nutrient removal,S.obliquus could completely remove inorganic phosphorus,and decrease ammonia nitrogen in ETD effluent by 81%.In addition,both C.aponinum OUC1 and S.obliquus cultivated in ETD exhibited extraordinary potential for biofuel production,increasing lipid productivities by 133%and 89%of that cultivated in ELR,respectively.As to ultrastructural changes,the differences in the lipoidal globules and glycogen granules of S.obliquus and C.aponinum OUC1 among the ETD and ELR treatments were mostly related to phosphorus limitations.The findings from this research reveal the probability using the secondary effluents as cultivation media to enhance algal biomass,nutrient removal and lipid productivity.

营养盐磷浓度对斜生栅藻生长的影响

设置0.01、0.05、0.10、0.15、0.20 mg/L 5个不同营养盐磷浓度梯度培养试验,研究不同磷水平对斜生栅藻(Scenedesmus obliquus)生长速率的影响。结果表明,斜生栅藻的生长与水体中磷浓度相关,在培养周期内,与对照组相比,不同磷浓度对斜生栅藻生长有促进作用,在磷浓度0.15 mg/L条件下,藻密度达到最高值,为129.25×10^(4)个细胞/mL,当磷浓度提高到0.20 mg/L时,藻密度降低到108.18×10^(4)个细胞/mL,说明在5个磷浓度梯度中,磷浓度0.15 mg/L为斜生栅藻生长最适浓度,而高于该浓度时会限制斜生栅藻的生长。单因素方差分析表明,在营养盐氮充足条件下,磷浓度提高促进了藻类暴发式生长,说明水体中磷浓度升高是水华产生的重要因素。

Efficient harvesting of green microalgae cells by magnetic flocculated Fe_(3)O_(4)nanoparticles combined with chitosan

Microalgae harvesting remains a challenging step in microalgae industrialization,thereby provoking the necessity to explore sustainable and economically feasible approaches.This research investigated the use of magnetic flocculated nanoparticles in the harvesting of the common microalgae Chlorella pyrenoidosa and Scenedesmus obliquus.The results showed that magnetic flocculated nanoparticles efficiently adsorbed negatively charged microalgae cells,and a magnetic field could adsorb the magnetic flocculated nanoparticles,thereby harvesting the microalgae cells.Harvesting efficiency was remarkably increased at the optimum magnetic field strength of 0.5 T with the magnetic flocculated nanoparticles at 0.738 g/L,and microalgae broth at pH 9.0,whereas the recovery rates of both C.pyrenoidosa and S.obliquus were around 97%and the sedimentation speed of both was above 2.63 cm/min.This study exemplified the magnetic flocculated nanoparticles-based approach to effectively harvest the microalgae cells.

酚类对栅列藻细胞的影响

作者测定了120余种化学药物,其中30余种为酚类化合物对斜生栅列藻的毒性影响。所用方法为在培养基内混入溶解后的各种药物,接种藻类后进行培养,观察效果。实验证明邻羟基苯甲醛和5,5’-二氯-2,2’-二羟基二苯甲烷及5种胺类化合物对藻类具有毒性。50ppm剂量的邻羟基苯甲醛和DDM足以杀死藻类,使藻类由绿色变成白色,叶绿体破坏,叶绿素消失。扫描电镜和透射电镜照片表明,两种药物的作用主要在破坏叶绿体和贮藏物淀粉粒。