| Title |
Excretion of Dissolved Organic Substances in the Photosynthesis and Autolysis Process of Cyanobacterium ( Blue - Green Algae ) |
| Authors |
( Eui Sin Lee ; Hyun Dong Lee ) |
| Abstract |
Two kinds of blue green algae, Phormidium tenue and Anabaena macrospora, were cultivated experimentally under bacteria-free condition, and the behaviors of extracellular substances excreted by both algae were investigated under light and dark condition. Under the light condition, the number of algal cells was increased by a hundredfold approximately with cultivation time, and DOC concentration of two cultures remained relatively constant level during the logarithmic growth phase. As the cultures entered into the stationary phase, DOC concentration began to accumulate. DOC excretion rates of Phormidium tenue and Anabaena macrospora were 0.013 and 0.048㎎ DOC/㎎ POC/day during the logarithmic phase, and 0.093 and 0.078㎎ DOC/㎎ POC/day during the stationary phase. The rates during the stationary phase were about 2 to 7 times higher than the logarithmic phase. The ratios of carbon concentration of carbohydrates to total DOC were almost constant. The values were 40% for Phormidium tenue and 60% for Anabaena macrospora during the overall incubation period. While, protein concentration increased during the stationary phase, and then leveled off. Under the dark condition, DOC concentration increased by the progress of algal autolysis, and DOC excretion rates by autolysis were estimated to be 0.045㎎ DOC/㎎ POC/day for Phormidium tenue and 0.024㎎ DOC/㎎ POC/day for Anabaena macrospora. The portion of cabohydrates was 50 to 60%, and protein was 5 to 30% in dissolved organic substances. In this study, it is confirmed that the components of algal by-products are different by algal species and the excretion of by-products was occured in the photosynthesis and autolysis period but not in respiration period. |