Author:

Abstract:

Pesticides and their derived degradation products are frequently found in groundwater at trace amounts (ng/L to µg/L range), but even then still exceed the EU limit (0.1 μg/L) for drinking water. This results in water subtraction well closure or the installation of expensive physico-chemical remediation techniques in drinking water production plants. Bioaugmentation, deploying microorganisms with dedicated catabolic pathways for xenobiotic degradation in contaminated systems to improve biodegradation, provides a green, sustainable alternative. Although, many bioaugmentation strategies were successful, at least as many also failed. Competition of the invading bacterial population with the indigenous community for resources and space are one of the important reasons for failure of bioaugmentation. This study examines the process of invasion in bioaugmentation strategies as being key in their success. The groundwater pollutant 2,6-dichlorobenzamide (BAM), a degradation product of the herbicide dichlobenil, is nowadays causing great difficulties for drinking water production plants. Aminobacter sp. MSH1, having robust BAM mineralization and the right properties for survival during starvation, was selected as a candidate for bioaugmenting sand filters treating BAM polluted drinking water. Continuously fed flow chambers were used to assess the invasion of MSH1 in a microbial community isolated from an operational sand filter. To determine the role of selective advantages such as C-sources for invasion by MSH1, BAM was either absent or present at micro- and macropollutant concentrations. MSH1 invasion succeeded and formed isolated aggregates in the multi-species biofilms away from other species. BAM degrading activity decreased only by 10% due to competition with other bacteria.