The term ''dissipotrophs'' is suggested for the bacteria that use simp
le monomeric substrates resulting from hydrolyzed polymers or originat
ing from other sources. The term ''dispersion microflora'' was earlier
suggested for this trophic group of bacteria. Most dissipotrophs belo
ng to prosthecate bacteria, which phylogenetically represent a single
group, part of the a-subclass of the proteobacteria. Dissipotrophs are
characterized by (a) the inability to utilize polymers, (b) a high af
finity for substrates present at low concentrations, and (c) low maxim
um specific growth rates. Dissipotrophs specifically consume a limited
number of substrates, a point discussed in this paper. Dissipotrophs
develop not only in habitats with a low organic substance content; the
y may also be abundant in ecosystems receiving large quantities of deg
radable organic substances if the metabolite concentration tends to de
crease due to a high density of microorganisms. ''Dissipotrophic bacte
ria'' can be a useful term in describing microbial communities.