Papers by Keyword: Microcystis aeruginosa

Abstract: Photocatalyst coatings had been successfully fabricated by molten salt treatment at 673 K for 3 h for titanium (Ti) coatings, which coated on alumina (Al₂O₃) balls by mechanical coating technique with Ti powder. The influence of molten salt treatment on the formed compounds, surface morphology and photocatalytic activity under visible light irradiation on degradation of MB solution and suppression of Microcystis aeruginosa of photocatalyst coatings was investigated. XRD results show that potassium titanate (K₂Ti₆O₁₃) forms on the surface of Ti coatings during molten salt treatment. The visible light photocatalytic activity of photocatalyst coatings has been effectively enhanced by molten salt treatment.

Abstract: The 1.5t/h algae and bacteria wastewater with high concentration was treated by hydroxyl radical (OH) produced by a strong ionization discharge. In this paper, the feasibility of kill bacteria and alga by OH was investigated, and effects of OH concentration, treatment time and pollution initial concentration on degrading microorganisms by OH were investigated in detail. The results indicated that the treatment process was effective in the degradation of the bacteria and alga at the initial pH value of 7.1, OH dosage of 2.33mg/L, the initial microcystis aeruginosa concentration of 10⁶/mL and the initial bacterial dosage of 10⁶cfu/mL, the bacteria and alga degradation rate reached 99.99% at 303K after 15min treatment. The results provided a theoretical basis for the OH treatment of microbial contamination in drinking water in large-scale.

Abstract: Microcystis aeruginosa is common in freshwater lakes, and developed easy. Instead of chlorophyll standard substance, fresh chlorophyll extraction from Microcystis aeruginosa applied to the determination of chlorophyll-a in water by fluorophotometry. Thus the relationship between concentration of chlorophyll-a and fluorescence intensity of Microcystis aeruginosa in water was established. The fluorescence intensity responded with the concentration of chlorophyll-a extract linearly in the range of 30~1800 ug/L with a correlative coefficient of 0.9947. Comparision was made between chlorophyll standard and the chlorophyll-a extraction of Microcystis aeruginosa, and no significant difference was found. In certain range of pH value and time, chlorophyll-a extraction from Microcystis aeruginosa is stable, and can be used to reflect the growth of algae in water quick, conveniently and accurately.

Abstract: In this study, algicidal effects of an algicidal bacterium, strain TL, on Microcystis aeruginosa were studied. The results demonstrate that the bacteria-algae ratio had a significant impact on algicidal effects. Illumination conditions affected the algicidal effects of TL as well. In illumination and darkness cycling, the optimum algicidal effects were realized. Algicidal mechanism of TL was further studied. TL may kill algae through the secretion of certain extracellular nonprotein substance. This research may provide technical basis for biological algae control of Microcystis aeruginosa.

Abstract: The experiment was conducted by small perspex ring groove, which generated infinitely long water flow, under axenic condition and constant temperature and light, to understand the effects of water flow on Microcystis aeruginosa growth in early summer and autumn raw water. The results showed that the algae growth was promoted and the specific growth rate was accelerated by water flow. The maximum biomass of M. aeruginosa in autumn raw water was higher than in early summer raw water at every flow rate. The optimum flow rate of M. aeruginosa in early summer and autumn raw water were 25 cm·s^-1 and 35cm·s^-1, respectively. The phenomenon may be the interaction of the colloid produced by death and decomposition of algae, and colony formation in M. aeruginosa under fluid motion. Therefore, The decomposition and morphology of Microcystis have an important role to growth and reproduction of algae, the results provided the scientific basis for revealing algal blooms.

Abstract: The experiment was conducted by a small perspex ring groove, which generated intermittent water flow, under axenic condition and constant temperature and light, to understand the effects of water flow on colony formation of Microcystis aeruginosa in the early spring raw water. The results showed that colony formation of Microcystis aeruginosa were observed in the control group and treatment groups. Colony characteristics in the treatment groups were more significant than in the control group, and the cell number of maximum colony in the treatment groups were 2.6-4 times more than in control group. So, water flow promoted to the colony formation of Microcystis aeruginosa, and colony of Microcystis aeruginosa most easily formed at flow rate of 25cm·s^-1. The phenomenon may be the interaction of the polysaccharide produced by algae in light and cell-cell higher contact rate in water flow. There are optimal flow rate of colony formation for too high water flow producing mechanical shear force to reduce colony formation. The represent study provided the scientific basis for revealing colony formation of algae.

Abstract: N-acyl homoserine-lactones (AHLs) are essential bacteria signaling molecules which regulate many physiological behaviors of Gram-negativebacteria. Previous studies have shown that AHLs can affect the growth and primary physiological processes of the bloom-forming cyanobacteriumMicrocystisaeruginosa. The aim of this study was to examine whether and how the presence of AHLs substances may affect the release of volatile chemicals of M. aeruginosa. Hydrodistillation and GC-MS were used to extract and analysis the volatile components of cells in exponential and stationary growth stage in normal growth condition and cells in exponential stage with additional AHLs. The results demonstrated that allelopathic chemicals existing in the stationary phase were induced and released when AHLs was added into the culture of cells in exponential phase, which indicated that AHLs may play role in growth state transition and interspecific competition in M. aeruginosavia regulation of production and release of volatile chemicals.

Abstract: The effect of bacterium N1 on the colony formation of the bloom-forming cyanobacterium Microcystis aeruginosa was investigated. The results showed that N1 could induce colony formation in M. aeruginosa in concentration-dependant way. Colony formation can efficiently decrease the damage caused by bacteria through polysaccharides synthesis to maintain the function of photosynthesis apertures.

Abstract: The laboratory experiment was conducted to investigated the effect of nickel over a concentration gradient of 0.1~1.00 mg/L on biomass ( indicated by absorbance of cell culture at 663nm wavelength ), superoxide anion (O₂•^ˉ), malondialdehyde (MDA), and superoxide dismutase (SOD) in the cyanobacterium Microcystis aeruginosa FACHB 905 isolated from Dianchi Lake, south west of China . The results showed: (1) M. aeruginosa could live normally in Ni (II)-absence culture medium，but 0.3 mg/L Ni(II) was the fittest concentration for test M. aeruginosa, in which biomass and SOD activity were highest among all test cultures; (2) Ni(II) induced O₂•^ˉ and MDA in M. aeruginosa cells under the experimental condition, showing that Ni(II) could influence on M. aeruginosa by inducing oxidative stress; (3) Fe-SOD and Mn-SOD were found in M. aeruginosa and both of them were induced by lower Ni(II) but inhibited by higher concentration. The multiformity of SOD isoenzymes enhance the resistance of M. aeruginosa to oxygen stress induced by unfavorable condition, which explained that M. aeruginosa is the preponderant species in badly polluted Dianchi Lake water for long period.

Abstract: Previous studies showed that abscisic acid (ABA) play a role in oxidative and osmotic stress response of cyanobacteria cells. Whether it has function in metal stress response remains unclear. The effect of exogenous Abscisic Acid on Cu²⁺ -Stress resistance of bloom-forming cyanobacteria Microcystis aeruginosa was studied in this paper. The results showed that 20 mg. l-1 exogenous ABA can effectively enhance the resistance ability of Microcystis aeruginosa cells to Cu²⁺-stress at the concentration of 0.25 mg.l-1. Exogenous ABA can restore the growth inhibition by elevating chlorophyll a, phycocyanin and allophycocyanin protein content in Cu²⁺ -stressed cells. ABA helps absorbing more metal ions to decrease its toxicity by inducing solvable protein and cellular polysaccharides biosynthesis. By promoting the Superoxide Dismutase and Glutathione Peroxidase activities, exogenous ABA can effectively help scavenge the excess superoxide radicals in the cells caused by Cu²⁺ -Stress. These results indicated that ABA might also play important role in metal-stress response and resistance.