The studies showed that the substrate consumption rate of a
co-culture was not always equal to the sum of consumption rates
of individual strains; besides, in a number of cases the activity of
a co-culture could be even lower than those of its constituent cultures
[11]. This effect can be explained by a competition between
co-culture’s strains for the most readily utilizable substrate. For
this reason, to make up a composition possessing a broad substrate
specificity, without competing interactions between its constituent
strains, it is required that the microorganisms possess different sets
of enzyme systems and, thus, supplement each other. One of the
approaches based on this principle is to include into co-cultures
strains of different taxonomic groups.