Dynamic models of multi-trophic interactions in microbial food webs

Non-steady-state mechanistic models were developed to examine the dynamics of organic pollutant utilization, microbial competition, inhibition and predation in a multi trophic system populated by bacteria of different growth rates and protozoa in a continuously mixed flow reactor and a batch reactor. The levels of substrate and cells were modeled during the biodegradation of naphthalene (a moderately bioavailable semi-volatile organic pollutant) by two bacteria in the presence of a predator assuming other nutrients were present in excess. The model predicts that multiple bacteria and predator species can co-exist in the system only if they differ in inhibition capacity, selective predation rate, and/or ability to employ predation defense mechanisms. These models further predict that predation can enhance the process of bioremediation, similar to what has been observed in some experimental studies. Together, these results provide a mechanistic model framework to support the idea that increased species diversity may increase the ability of microbial ecosystems to biodegrade pollutants.