DISTRIBUTION OF SYNECHOCOCCUS SPP. DETERMINED BY IMMUNOFLUORESCENT ASSAY

By using two polyclonal antisera against WH 7803 strain (Synechococcus sp.) and WH 5701 strain (Synechococcus bacillaris) it is possible to detect and to enumerate cells of the two cyanobacterial serogroups. Th e immunofluorescence technique was used to study the distribution of t he two serogroups in the estuarine, coastal and upwelling waters of th e Mediterranean Sea surrounding Messina. In the estuarine waters of th e Alcantara River (Ionian Sea), the WH 7803 serogroup was present at a concentration in the order of 10(2) cells ml(-1) and the WH 5701 sero group at a concentration of 5.5 x 10(2) cells ml(-1). In the coastal w aters of Messina, where urban and industrial wastes are usually dumped , the concentration of total phycoerythrin-Synechococcus ranged from 1 .3 x 10(2) to 4.1 x 10(3) cells ml(-1) the WH 7803 serogroup accounted for 50-94% of the total population in Ionian stations, whereas the WH 5701 serogroup ranged from 1.4 x 10(1) to 6.7 x 10(2) cells ml(-1). I n the upwelling area (Straits of Messina) both serogroups were found. Vertical distribution of two Synechococcus strains had an opposite tre nd and their concentrations were of the order of 10(1)-10(2) cells ml( -1). The use of the Scan laser system allows both autofluorescent and labelled organisms to be distinguished in a preparation for optical mi croscopy. It also allows false-positive cells to be distinguished.