About the order in aerobic heterotrophic microbial communities from hydrocarbon-contaminated sites

Abstract

The organizational structure of communities of aerobic heterotrophic bacteria was studied by means of physiological and molecular typing of the members of arbitrary samples of isolates, ASsI. The isolate sample assay (ISA) was applied to three different hydrocarbon-polluted sites: a dry windrow pile for bioremediation of waste oil-contaminated soil, a fuel-contaminated ground water aquifer requiring evaluation, and an in situ enclosure for pyrolysis–wastewater treatment installed in a lake-sized lignite carbonization effluent deposit. Examples are given for the following findings, namely that similar percentages of pollutant-degradation abilities in heterotrophic communities, embodied by the ASsI, (i) can be based on different contributions of the members in each community, (ii) can coincide with different species compositions, and (iii) can coincide with different general (Biolog) substrate utilization patterns. Because the individual members in the ASsI evidently complemented one another in their site-relevant features to exhibit, as a group, a reproducible and site-specific overriding pattern, it seems justified to call these groups communities. Multiple site-relevant degradation abilities of the individual members of the ASsI suggest, as essential contributions to the formation of similar community degradation patterns, the simultaneous utilization of mixed pollutants by the respective bacteria. Because evidently no cell to cell communication is needed for the expression of similar degradation patterns, it is suggested that the communities are self-regulating systems which are formatted by the carbon compound supply.