[Effects of Algicidal Substance on Phaeocystis globosa and Its Fatty Acids by the Simulation Experiment].

In order to evaluate the effects of algicidal substance on Phaeocystis globosa (P. globosa) and its algal toxin-fatty acids, the changes of chlorophyll-a, pH, dissolved oxygen, permanganate index and N, P concentration were evaluated by the simulation experiment. Fatty acids composition in P. globosa was detected by GC-MS. After adding algicidal substance in simulative water with the volume ratio 1: 100, the levels of chlorophyll-a, pH and permanganate index were reduced, while the concentrations of dissolved oxygen and N, P were increased significantly within 14 days. Comparing with control group after 14 days, pH was reduced to 7. 51 from 8. 50, chlorophyll-a and permanganate index were reduced by 82. 3% (P < 0. 05) and 55. 2% (P < 0. 01), respectively. Dissolved oxygen was significantly increased by 29. 5% (P < 0. 05). The concentrations of NH4+ -N, NO2- -N, NO3- -N and PO(4)3- -P were respectively 0. 46, 1. 50 , 6. 24 and 1. 30 times higher than that in control group. 14 days after the addition of algicidal substance, the total fatty acids of P. globosa were reduced by 83. 4%. The major fatty acids C18:2, C16:0, and C18:1, were reduced by 100%, 97. 7% and 85. 4% (P <0. 01), respectively. Our results indicated that algicidal substance from Bacillus sp. BI can effectively inhibit the growth of P. globosa and reduce the concentration of algal toxin-fatty acid in the simulation experiment. This study provides a theoretical basis for ecological safety of algicidal substance form Bacillus sp. strain Bl.

[Characteristics study of extracellular active substance of Bacillus sp. B1 on Phaeocystis globosa].

The algicidal bacterium named B1 which was identified as Bacillus sp. was isolated from red tide water in Xiangzhou shipside of Zhuhai. The algicidal mode of algae-lysis bacterium B1 and the microstructure of algal cells in the algae-lysing process were studied. In order to explore the properties of extracellular algicidal substances, the sterile condensed bacteria-free filtrate was dialysed, sedimentated by ethanol, extracted by organic solvents and exposed in different heat and pH variations. The results showed that the sterile condensed bacteria-free filtrate could effectively dissolve Phaeocystis globosa (P. globosa), the removal rate was 94.9%, B1 excreted algae-lysing substances to inhibit the growth of algae indirectly. Algicidal process under the visual field of microscope demonstrated that the alga cell rounded and the cell wall lost integrity after 16 h, the algae cell lysed and cellular substances released after 56 h. The molecular weight of the extracellular algae-lysing components of B1 are less than 3 500, the algicidal substances have strong polarity and heat-tolerant, which still had a strong algae-lysing effect after being treated at 121 degrees C, and the removal rate was 92.6%. The algae-lysing ability was stronger while the pH value was kept at 9.0, ethanol can separate extracellular algae-lysing components from other components efficiently. The algae-lysing components may be non-bioactive molecules which contain acidic or alkaline groups, and may not be protein, nuclear acid and polysaccharides.

[Isolation and characterization of two marine algicidal bacteria against the Phaeocystis globosa].

The algae-lysis bacteria Y01 and Y04 were isolated from seawater, during a red tide survey of the Zhuhai Estuary in southern China. The algae-lysis bacteria Y01 and Y04 were Gram-positive bacteria which can remove P. globosa in 6 days. The lysing process was observed by microscope and SEM, both of them could directly lyse P. globosa. The strains were identified by the sequence analysis of 16S rDNA. The length of the two bacteria's sequences were 1 468 bp and 1 548 bp (strain Y01: DQ531607; strain Y04: DQ531608). The DNA sequence similarity searches showed that share more than 99.7% sequence homology with some strain of Bacillus. The algae-lysing bacteria would provide a possibility to control P. globosa red-tide by microbial agents.

NMR spectral assignments of two sterols from a soft coral Sinularia brassica.

Two new steroids, named 4α,22-dimethyl-Cholest-22-en-3ß-ol (1) and 4α-methyl-Cholest-7,22-dien-3ß-ol (2), along with two known steroids, were isolated from the soft coral Sinularia brassica. The structures of the new compounds were determined on the basis of extensive spectroscopic data (MS, (1)H and (13)C NMR, (1)H-(1)H COSY, (13)C-(1)H COSY, HMBC and NOESY) analysis.

[Sodium dichlorinated isocyanuric acid and trichloroisocyanuric acid for removing cells of Phaeochystis globosa].

Removal and control of Phaeochystis globosa cells by sodium dichlorinated isocyanuric acid and tri-chloroisocyanuric acid were studied. Removal efficiency of the two algaecides was contrasted and removal mechanism was also discussed. The results suggest both of the algaecides have excellent ability to remove and control Phaeochystis globosa cells. Hypochlorous acid is released slowly by the two algaecides and maintains it's stabilization. The effective concentration of available chlorine is 4.5 mg/L. The removal efficiency is more than 90% within 24 hours at the available chlorine's dosage of 5.0 mg/L. Trichloroisocyanuric acid could remove Phaeochystis globosa cells more effectively than sodium dichlorinated isocyanuric acid when concentration of available chlorine was more than 5.0 mg/L. The conclusion was identified by t test of available chlorine and removal efficiency.