In the present investigation, we looked into the relationship
between the genetic diversity of microbial populations
in compost and the enzymatic activity of chitinase. The
suppressive effects on different plant pathogens by composts
are well documented (Hoitink et al., 2001) but in
most cases the actual mechanisms by which this happens
are unknown. However, it has been suggested that chitinase
activity may play a role by causing lysis of pathogenic
fungi (Boulter et al., 2000; Labrie et al., 2001). Therefore,
we tried to induce chitinase activity by supplementing
two types of compost (source separated organic household
waste and garden/park waste compost) with chitin and
measured the chitinase activity using a very sensitive fluorogenic
substrate that previously has been used to detect
enzyme activity in soils (e.g., Marx et al., 2001). To link
the chitinase activity of the microbial populations in the
compost to the genetic diversity, we employed denaturing
gradient gel electrophoresis (DGGE). Because chitin
has high nitrogen content (6.8% by weight) and as a