Microbial Degradation and Preliminary Chemical Characterization of Microcystis Exopolysaccharides from a Cyanobacterial Water Bloom of Lake Taihu

A bloom biomass composed mainly of Microcystis spp. was harvested from Lake Taihu, China. Exopolysaccharides (FEPS, exopolysaccharides from field‐grown Microcystis spp.) were extracted from the bloom mass with 3% glutaraldehyde. FEPS contained 5.4% protein and 6.9% uronic acid (glucuronic acid and galacturonic acid). The neutral sugar composition of FEPS consisted of rhamnose, arabinose, mannose, glucose and galactose in a relative molar ratio of 4.8: 4.2: 2.1: 3.7: 1.0, respectively. The dialyzed FEPS exhibited strong interaction with metal ions. Besides macromineral elements Ca, Mg, Na and K, micromineral elements Zn, Mn, Sr, Fe, Cu and Al were also detected in FEPS. The composition of FEPS is discussed with respect to its possible effects on colony formation, and bioavailability and cycling of metals in the lake. FEPS was able to be degraded rapidly at a rate of 50% in 18 d in the beginning at 25 °C after inoculation of the natural bacterial community from the bloom zone, indicating that FEPS could be recycled in nature. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)