| Abstract: | Mathematical models are developed describing unsteady-state bacterial growth on organic polymers that are hydrolyzed by extracellular enzymes secreted by the bacteria to yield low-molecular-weight oligomers that may be directly transported across bacterial cytoplasmic membranes and hence metabolized. Two different modes of extracellular enzyme action on the organic polymer are considered. In one case, the enzyme is exoacting yielding a transportable oligomer with each polymer bond hydrolyzed. In the other case, the enzyme is endoacting yielding a series of oligomers upon random cleavage of the polymer bonds with oligomers up to a certain chain length assumed to be transportable. These models are exploited to show under what circumstances the rate of hydrolysis by the extracellular enzyme to yield transportable oligomers influences the bacterial growth rate. It is shown that an initial lag period, an accentuated declining growth phase, and a low overall rate of bacterial growth will be some of the manifestations when the rate of hydrolysis has a strong influence. |
