HIGH LIPOXYGENASE ACTIVITIES IN EPILITHIC BIOFILMS OF DIATOMS

We describe the occurrence of lipoxygenase and carotene oxygenase acti vities in epilithic biofilms of an unpolluted brook and changes in the ir patterns during spring development of the biofilms from April to Ju ly. The biofilms developed on pebbles in the brook bed and consisted m ainly of diatoms (Achnanthes minutissma, Amphora pediculus, Cymbella m inuta and Gomphonema angustum). The abundance of species was severely affected by a storm-flow in May that initiated a new development of th e biofilms. Lipoxygenase activities determined by the generation of vo latile organic products, such as 2(E),4(Z)-heptadienal, 2(E),4(Z)-octa dienal, octa-1,5-dien-3-ol. 1,3(E),5(Z)-octatriene and ectocarpene wer e always present but the specificities of the cleavage reactions diffe red with the species composition. Nor-carotenoids were determined as i ndicators of carotene oxygenases.