Interspecies Interactions of the 2,6-Dichlorobenzamide Degrading Aminobacter sp. MSH1 with Resident Sand Filter Bacteria: Indications for Mutual Cooperative Interactions That Improve BAM Mineralization Activity

Abstract

Bioaugmentation often involves an invasion process requiring the establishment and activity of a foreign microbe in the resident community of the target environment. Interactions with resident micro-organisms, either antagonistic or cooperative, are believed to impact invasion. However, few studies have examined the variability of interactions between an invader and resident species of its target environment, and none of them considered a bioremediation context. Aminobacter sp. MSH1 mineralizing the groundwater micropollutant 2,6-dichlorobenzamide (BAM), is proposed for bioaugmentation of sand filters used in drinking water production to avert BAM contamination. We examined the nature of the interactions between MSH1 and 13 sand filter resident bacteria in dual and triple species assemblies in sand microcosms. The residents affected MSH1-mediated BAM mineralization without always impacting MSH1 cell densities, indicating effects on cell physiology rather than on cell number. Exploitative competition explained most of the effects (70%), but indications of interference competition were also found. Two residents improved BAM mineralization in dual species assemblies, apparently in a mutual cooperation, and overruled negative effects by others in triple species systems. The results suggest that sand filter communities contain species that increase MSH1 fitness. This opens doors for assisting bioaugmentation through co-inoculation with “helper” bacteria originating from and adapted to the target environment.

Cooperative interactions between invader and resident microbial community members weaken the negative diversity‐invasion relationship

“…Our study shows that the presence of K169 and K27 supports the preservation of MSH1's fitness even at high R SFI levels. This reinforces the idea of using specific residents of the target environment as co-inocula for prolonging MSH1's viability and functionality as previously proposed for K169 based on its cooperative pairwise interactions with MSH1 (Vandermaesen et al, 2022). The support of growth of a lower fitness micro-organism by commensals was reported before (Morris et al, 2013).…”

“…We hypothesized that cooperative interactions between the invader and the resident, in a form of mutualism and/ or commensalism, affect the diversity-invasion relationship. Recently, Vandermaesen et al (2022) examined how pairwise interactions between Aminobacter niigataensis MSH1, capable of mineralizing 2,6-dichlorobenzamide (BAM), and 13 heterotrophic bacterial strains isolated from sand filters exploited in drinking water treatment plants (DWTPs) affected the MSH1 BAM mineralizing functionality and MSH1 cell densities. BAM is a common groundwater micropollutant in Europe and a threat for drinking water production, while MSH1 is used as a bioremediation agent for bioaugmentation of DWTP sand filters to avert BAM pollution Horemans, Raes, et al, 2017).…”

“…To test our hypothesis, we examined how the BAM mineralization functionality and survival of A. niigataensis MSH1 was affected when inoculated together with different synthetic combinations of the SFI strains at increasing initial richness (up to richness 13) in sand microcosms. Each SFI was previously shown to either positively or negatively affect MSH1 functionality in pairwise assemblies (Vandermaesen et al, 2022). (Vandermaesen et al, 2017).…”

The Growth Yield of Aminobacter niigataensis MSH1 on the Micropollutant 2,6-Dichlorobenzamide Decreases Substantially at Trace Substrate Concentrations

“…Indeed, the advantage of additional growth on background AOC was demonstrated in experiments 1 and 2, showing more rapid BAM degradation in non-AOC-restricted MMO containing substantial AOC MSH1 compared to that in AOC-restricted MMO in which most of the AOC MSH1 was removed. The amounts and type of AOC available for MSH1 may however vary in different input waters and systems affecting the activity of MSH1 and the success of bioaugmentation efforts. , Moreover, coincidental microbiota will compete for the AOC which might depend on the diversity of microbiota present. ,, Therefore, it is of interest to further investigate how the AOC in field water matrices as well as the presence of competing microbiota affect MSH1 growth kinetics and BAM biodegradation. In addition, in the case that loss of inducibility of the 2,6-DCBA catabolic gene cluster(s) is responsible for the nongrowth linked degradation of BAM at these concentrations, then BAM will not be completely mineralized.…”

“…15,30 Moreover, coincidental microbiota will compete for the AOC which might depend on the diversity of microbiota present. 15,30,55 Therefore, it is of interest to further investigate how the AOC in field water matrices as well as the presence of competing microbiota affect MSH1 growth kinetics and BAM biodegradation. In addition, in the case that loss of inducibility of the 2,6-DCBA catabolic gene cluster(s) is responsible for the nongrowth linked degradation of BAM at these concentrations, then BAM will not be completely mineralized.…”