Component structure and characteristic analysis of cyanobacterial organic matters

Abstract

The characteristic analysis of cyanobacterial organic matters is an important premise of cyanobacterial organic pollution control. This paper investigated the component structure characteristics of algal organic matters (AOM) secreted and released by cyanobacteria in laboratory culture and actual Taihu Lake environment by spectroscopic quantitative and qualitative methods. Results showed that the secretion amount of AOM was mainly 4–6 μg COD/106 cells during the growth period of Microcystis aeruginosa, and the content ratio of extracellular organic matters (EOM) to intracellular organic matters (IOM) gradually increased from 0.83 in adaptation and logarithmic period to 3.33 in stable and decay period. The secretion of IOM showed a decrease trend, which indicated the decrease of its synthesis or the gradual infiltration and loss caused by cell membrane damage. From the component characteristics, the EOM had lower SUVA value and higher proportion of small molecular substances with molecular weight <3 kDa, indicating its more difficult to separate from water than IOM. Compared with the laboratory culture environment, the actual Taihu Lake resulted in more obvious characteristic heterogeneity of cyanobacteria EOM and IOM. HIGHLIGHTS The cyanobacteria released EOM was related to cell metabolic rate.; The cyanobacteria secreted IOM was related to nutrient supply and cell condition.; EOM had more small molecular components with lower SUVA value than IOM.; EOM was prone to be degraded and transformed to low molecular level and rich component types in Taihu Lake, making the control of organic pollution from cyanobacteria more difficult.;

Keywords

• algal organic matters
• cyanobacteria
• extracellular organic matters
• intracellular organic matters
• secretion characteristics