Interactions between gems and indigenous microorganisms in aquatic ecosystem

Abstract

This study was conducted to elucidate the interaction and biotic effect of indigenous microorganisms, especially micro animals and bacteria on prosperity and decay of GEMs (genetically engineered microorganisms). Bacterial interaction means competition for substrate to grow between GEMs and indigenous bacteria, and prey-predator interaction means effect of micro animals on survival of GEMs. So, it is considered that basic part of environmental effects of GEMs will be made clear with analysi of these phenomena. Escherichia coli HB101/pBR325 as GEM, its host strain E.coli HB101, and Bacillus cereus MC as one of dominant species of indigenous bacteria were supplied. As predator the micro animals, Tetrahymena thermophila (ciliata, filter feeder) and Aeolosoma hemprichi (oligochaeta, detritus feeder) were supplied. The results obtained from this study can be concluded as follows: 1) GEMs showed few potentials to beat their host strains in their growth competition; 2) predation of micro animals influenced equally GEMs and their host strains, and these microorganisms, such as bacteria, were expected to decrease in environment; 3) floculation enabled GEMs to escape from predation of micro animals, but GEMs were not expected to survive long-term because various predator species of micro animals exist in environment; 4) effect of micro animals, especially their predation, on survival of GEMs was so important that more practical research should be conducted; 5) it suggests that the results obtained from this study can be used to establish regular guidelines for environmental release of GEMs such as bioremediation technologies.