Abstract
The marine angiosperm Posidonia oceanica develops extensive meadows across the Mediterranean coast, with an important ecological role in the sea environment. These meadows are declining, probably due to a complex combination of both physical and chemical factors. However, biotic factors could also be contributing in some extent to seagrass decline. Enzymatic activities of bacterial isolates belonging to several genera recovered from different tissues of P. oceanica were analyzed, both by the miniaturized system API ZYM, and by hydrolysis of plant components in agar plates. The results indicate that isolates of Pseudoalteromonas spp. and Alteromonas spp. have the greatest enzymatic activity. A high degradative potential suggests that some bacteria recovered from P. oceanica could cause lesions in the plant, making it more susceptible to the attack by pathogenic bacteria or other microorganisms that can use these portals of entry, or increasing its susceptibility to any other stress factor.