Light-induced changes in photosynthesis and structure of cyanobacteria cultured biofilms from an Italian wastewater treatment plant

The photosynthetic and light acclimation capability of phototrophic biofilms collected seasonally from the wastewater treatment plant (WWTP) of Fiumicino Airport (Rome, Italy) was tested in culture at different irradiance conditions. Photosynthesis versus Irradiance (P/I) curves were recorded on 15, 30 and 45 day aged communities and chlorophylls, carotenoids and phycobiliproteins quantified. Light microscopy observations were performed to evaluate inoculum species composition and taxonomic shifts over time in cultured biofilms. Phototrophs acclimated to different irradiances by varying the photosynthetic efficiency, maximum photosynthetic rate and pigment content. Community age and biomass variation also affected photosynthesis-light response. Marked shifts towards the prevalence of cyanobacteria were observed in summer and autumn biofilms kept at the highest experimental irradiances. Data indicated high productivity and acclimation potential of cultured phototrophic biofilms in view of their application for bioremediation technologies