Niche creation improves bioaugmentation of an organic micropollutant degrader in oligotrophic waters

Bioaugmentation of sand filters is an alternative process for eliminating organic micropollutants in drinking water treatment. Bioaugmentation resembles an invasion process and niche availability is a prime determinant for successful invasion. This is particularly relevant for bioaugmentation of oligotrophic environments where organic micropollutants (OMPs) hardly provide a selective C-source and exploitative competition for the scarce intrinsic organic carbon exists between inoculated OMP-degraders and resident microbiota. Building on microbial invasion theories, we tested the hypothesis that the success of bioaugmentation and associated OMP degradation can be enhanced through niche creation by supplying a selective carbon source for the introduced degrader. Sand filter microbiota reduced growth of the 2,6-dichlorobenzamide degrading strain Aminobacter niigataensis MSH1 and 2,6-dichlorobenzamide degradation in different natural waters. This was counteracted by adding benzamide as a selective C-source for MSH1 resulting in a 3-fold faster 2,6-dichlorobenzamide biodegradation and a 6-fold increase in MSH1 growth. An additive biokinetic model underpredicted growth of MSH1 in the presence of sand filter microbiota suggesting that the community, despite its overall negative effect, supported MSH1 growth. Moreover, benzamide retarded 2,6-dichlorobenzamide degradation likely due to enzyme competitive inhibition. The results demonstrate the use of deliberately creating dedicated niches selective for the inoculum and the successful translation of ecological invasion theories into microbial community management, for improved bioaugmentation of complex communities.