INFLUENCE OF NUTRIENT FACTORS ON PRODUCTION OF MUCILAGE BY AMPHORA-COFFEAEFORMIS VAR PERPUSILLA

Widely distributed productions of mucilages affected the coasts of the Adriatic sea in the summers of 1988, 1989 and 1991 (the so-called ''d irty sea'' phenomenon). Samples taken in this area revealed a mix of d iatom and dinoflagellate algae trapped in the mucilagenous matrix, but cultured isolates from the samples showed the species Amphora coffeae formis var. perpusilla producing a kind of exopolysaccharide (EPS) ver y similar in structure to that of the floating pillows which appear in the Adriatic waters. The effects of growing concentrations of primary nutrients on EPS production by A. coffeaeformis were evaluated and th e results showed a prevailing influence of nitrogen, alone or in syner gy with phosphorus, with respect to phosphorus alone. EPS production n ever stopped, even during the stationary phase and never overlapped wi th growth curves. (C) 1997 Elsevier Science Ltd.