Analysis of How a Biofilm Forms on the Surface of the Aquatic Macrophyte Phragmites australis.

The process by which a biofilm forms on the surface of the aquatic macrophyte Phragmites australis was investigated over a period of about two months (from mid-May to late-July, 2008) in Lake Biwa. The biofilm formed relatively quickly, its wet weight per unit area after seven day being that of a mature biofilm. This speed can be attributed to the many active bacteria in the early stage of its formation and the extracellular polymeric substances (EPS) they produce. The EPS carried electric charges that attracted nutrient ions from surrounding lake water, which, by electrostatic interaction, reached a high concentration as early as day 7 of the formation process. This significantly affected the biofilm community, which differed greatly from that of the lake water even at the beginning of biofilm formation. Brown amorphous compounds (a complex of organic and inorganic substances), covered the biofilm in the second half of its formation process producing a different community structure from that initially. This study revealed a fast and dynamic process of biofilm formation on the reed surface of reed.