He Yanzhao

Effects of temperature on the growth and generation of extracellular organic matter of Microcystis aeruginosa and Anabaena sp.

We investigated the growth characteristics and dynamic variations of extracellular organic matter( EOM) under the temperature of 35,25 and 10℃ using Microcystis aeruginosa and Anabaena sp.,the two dominant species in Lake Chaohu,and the targeting cyanobacteria in the present study. The results showed that culture temperature played an important role in cell density,alkaline phosphatase activity( APA),and the release of EOM. The most adaptive temperature for Microcystis aeruginosa and Anabaena sp. was 25℃,with the maximum cell densities of 3. 12 × 107 and 2. 03 × 107 cells /ml,respectively. The characteristics of APA under different temperature conditions proved that the inhibition effect of high temperature on the growth of Microcystis aeruginosa and that of low temperature on the growth of Anabaena sp. Total amount of EOM was determined by cyanobacterial biomass and the release rate of unicellular EOM. The highest amounts of dissolved organic carbon and extracellular polysaccharide substances( EPS) for Anabaena sp. were 49. 28 and 38. 46 mg /L at 25℃,and 45. 82 and 40. 60 mg /L at 35℃,respectively,whereas low temperature of 10℃ restricted the release of EOM of the two studied cyanobacteria. The results of highest amount of unicellular EPS at 35℃ for Anabaena sp. and at 10℃ for Microcystis aeruginosa suggested that adverse growth conditions promotedthe generation of EPS. Excitation-Emission Matrice of EOM showed that main EOM of Microcystis aeruginosa and Anabaena sp.were protein-like and humic acid-like organic substances. Furthermore,the concentrations of organic matters rather than the types of organic matters were influenced by temperature.We investigated the growth characteristics and dynamic variations of extracellular organic matter( EOM) under the temperature of 35,25 and 10℃ using Microcystis aeruginosa and Anabaena sp.,the two dominant species in Lake Chaohu,and the targeting cyanobacteria in the present study. The results showed that culture temperature played an important role in cell density,alkaline phosphatase activity( APA),and the release of EOM. The most adaptive temperature for Microcystis aeruginosa and Anabaena sp. was 25℃,with the maximum cell densities of 3. 12 × 107 and 2. 03 × 107 cells /ml,respectively. The characteristics of APA under different temperature conditions proved that the inhibition effect of high temperature on the growth of Microcystis aeruginosa and that of low temperature on the growth of Anabaena sp. Total amount of EOM was determined by cyanobacterial biomass and the release rate of unicellular EOM. The highest amounts of dissolved organic carbon and extracellular polysaccharide substances( EPS) for Anabaena sp. were 49. 28 and 38. 46 mg /L at 25℃,and 45. 82 and 40. 60 mg /L at 35℃,respectively,whereas low temperature of 10℃ restricted the release of EOM of the two studied cyanobacteria. The results of highest amount of unicellular EPS at 35℃ for Anabaena sp. and at 10℃ for Microcystis aeruginosa suggested that adverse growth conditions promotedthe generation of EPS. Excitation-Emission Matrice of EOM showed that main EOM of Microcystis aeruginosa and Anabaena sp.were protein-like and humic acid-like organic substances. Furthermore,the concentrations of organic matters rather than the types of organic matters were influenced by temperature.