Recent advances in molecular microbial ecology have provided microbiol
ogists with a wealth of information on the extent of phylogenetic rela
tedness among cultured organisms and the composition of microbial comm
unities. However, in order to understand microbial ecology, more is ne
eded than just the determination of novel types of organisms. Another
important factor in the reconstruction of the foodweb as a driving for
ce in ecosystem function is the knowledge of biochemical properties an
d/or the presence of genes coding for enzymes involved in biochemical
pathways of isolated and non-cultured strains. While the structure of
an environmental sample can in principle now be elucidated by determin
ation of the intraspecific relationships between microorganisms, metho
ds that would explore species richness and species abundance, as well
as functional dependence between organisms and between the organisms a
nd the organic and inorganic components of the sample are less well ex
plored.