[Niche analysis of phytoplankton's dominant species in Dianshan Lake of East China].

By using modified Levins and Petraitis formulae, this paper determined the niche breadth and niche overlap of the phytoplankton's dominant species in Dianshan Lake of East China, and analyzed the relationships between the niche breadth and niche overlap and the density and dominance of the dominant species. The niche breadth and niche overlap of the dominant species differed in different periods, and different dominant species had different adaptive capacity to the environmental factors. Based on their niche breadth in different seasons, the dominant species in the Lake could be classified into four groups, among which, Chroomonas acuta and Chlorella vulgaris had broader niche, more quantity, wider distribution, and better use of environmental resources. During cyanobacterial blooms, the niche overlap among Cyanophyta species was comparatively higher, Microcystis aeruginosa had broader niche breadth, but other species showed lower niche breadth. Correlation analysis showed that the dominance of the dominant species in different seasons had significant correlation with their niche breadth, and the dominant species density had significant correlation with their niche overlap.

[Biological synthesis of L-ascorbyl palmitate].

Biological synthesis of L-Ascorbyl Palmitate in organic system were studied in this text. The contradiction between conversion of vitamin C and concentration of L-Ascorbyl Palmitate were resolved. High conversion of vitamin C and concentration of L-Ascorbyl Palmitate were obtained by Novo435. A series of solvents(log P from -0.24 to 3.5 )were investigated for the reaction,and acetone was found to be the most suitable from the standpoint of the enzyme activity and solubility of L-ascorbic. And the equilibrium of the reaction was affected by the addition of the molecular sieves and temperature. Reaction carried out at 60 degrees C and with 20% 0.4nm molecular sieves is good for the enzyme to keep its activity and for making the equilibrium go to the product. With 1.094 g palmitic acid, 0.107 g vitamin C and 0.020 g Novo435, rotate rate of 200 r/min, the conversion of ascorbic reached 80% and the concentration of L-ascorbyl palmitate is 20 g/L after 48 h. Furthermore, reaction batch of Novo435 and substrates recycle were observed, the result indicated that Novo435 may used 4-5 times continuously with high conversion. And 6-O-unsaturated acyl L-ascorbates were synthesized through Novo435 condensation of ascorbic acid and various unsaturated fatty acids with high conversion in this text.