Effect of light intensity on bound EPS characteristics of two Microcystis morphospecies: the role of bEPS in the proliferation of Microcystis

• Published in: Journal of oceanology and limnology Vol. 40; no. 5; pp. 1706 - 1719
• Main Authors: Wang, Xianzhe, Han, Xingye, Ge, Hongmei
• Format: Journal Article
• Language: English
• Published: Heidelberg Science Press 01.09.2022; Springer Nature B.V; School of Civil Engineering,Architecture and Environment,Hubei University of Technology,Wuhan 430068,China; Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization,Wuhan 430068,China
• Subjects: Analytical methods; Earth and Environmental Science; Earth Sciences; Emission analysis; Excitation spectra; Extracellular polymers; Fluorescence; Lakes; Light; Light intensity; Luminous intensity; Microcystis; Oceanography; Physiochemistry; Potentiometers; Proliferation; Spectroscopy; Tryptophan; Zeta potential; light intensity; bound extracellular polymeric substances; zeta potential; Microcystis
• ISSN: 2096-5508; 2523-3521
• DOI: 10.1007/s00343-022-1362-4

Bound extracellular polymeric substances (bEPS) play an important role in the proliferation of Microcystis . However, the understanding of bEPS characterization remains limited. In this study, three-dimensional fluorescence excitation-emission matrix (3D-EEM) spectroscopy and zeta potentiometer were used to characterize the loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) from two dominant Microcystis morphospecies from Taihu Lake (China) at different light intensities. Physiochemical analysis showed that the growth and TB-EPS or bEPS contents in Microcystis aeruginosa were higher than those in Microcystis flos-aquae at each light intensity. The 3D-EEM contour demonstrated that the intensities of peak B (tryptophan-like substances) in the TB-EPS from M. aeruginosa were stronger than those from M. flos-aquae when the light intensity was higher than 10 µE/(m 2 ·s). Zeta potential analysis showed that the absolute values of the zeta potential of TB-EPS in the two species both increased with rising light intensity, except those of TB-EPS in M. aeruginosa at 105 µE/(m 2 ·s). Moreover, the absolute values of the zeta potential of M. aeruginosa were higher than those of M. flos-aquae at each light intensity. All these results indicated that M. aeruginosa may more quickly proliferate than M. flos-aquae through increased negative charges, bEPS contents, growth, and tryptophan-like substance contents at certain light intensities.