Leucine arylamidase activity in the phyllosphere and the litter layer of a Scots pine forest.

The activity of the leucine arylamidase (EC 3.4.11.2) was measured in washings of green needles from the canopy and dead needles from the litter of Scots pine throughout one year. It was highest in the litter and markedly higher in 2-year-old needles than in young ones, which were colonized by only a few bacteria. The leucine arylamidase activity largely arose from microbial epiphytes. Screenings for the potential of the enzyme activity among strains of a collection of phyllosphere microorganisms isolated from forest trees revealed that the leucine arylamidase activity was more abundant among bacteria (79%) and yeasts (57%) than among filamentous fungi, whereas the opposite was true in degrading complex proteins by proteinases.