Aminobacter MSH1-Mineralisation of BAM in Sand-Filters Depends on Biological Diversity

Abstract

BAM (2,6-dichlorobenzamide) is a metabolite of the pesticide dichlobenil. Naturally occurring bacteria that can utilize BAM are rare. Often the compound cannot be degraded before it reaches the groundwater and therefore it poses a serious threat to drinking water supplies. The bacterial strain Aminobacter MSH1 is a BAM degrader and therefore a potential candidate to be amended to sand filters in waterworks to remediate BAM polluted drinking water. A common problem in bioremediation is that bacteria artificially introduced into new diverse environments often thrive poorly, which is even more unfortunate because biologically diverse environments may ensure a more complete decomposition. To test the bioaugmentative potential of MSH1, we used a serial dilution approach to construct microcosms with different biological diversity. Subsequently, we amended Aminobacter MSH1 to the microcosms in two final concentrations; i.e. 105 cells mL-1 and 107 cells mL-1. We anticipated that BAM degradation would be most efficient at “intermediate diversities” as low diversity would counteract decomposition because of incomplete decomposition of metabolites and high diversity would be detrimental because of eradication of Aminobacter MSH1. This hypothesis was only confirmed when Aminobacter MSH1 was amended in concentrations of 105 cells mL-1.Our findings suggest that Aminobacter MSH1 is a very promising bioremediator at several diversity levels.

Bioaugmentation Mitigates the Impact of Estrogen on Coliform-Grazing Protozoa in Slow Sand Filters

“…Therefore, future work should also aim to enhance the survival of exogenous organisms in augmented SSFs by either augmentation at successive stages of the SSF lifecycle (e.g., after biofilm maturation or SSF ripening) or through biostimulation of the estrogen-degrading bacteria which may allow for realistic scaling up to full-scale SSFs. Furthermore, building on the findings from Ekelund et al (2015) 55 who showed that the level of bacterial diversity in sand filters affected the degradation of BAM – a metabolite of the pesticide dichlobeni – future studies should explore the optimization of the bacterial diversity in augmented systems.…”

“…In addition to “bottom-up” effects of bioaugmentative bacteria, such as in this SSF study, positive – and negative – “top-down” feedback mechanisms from a variety of meiofauna have been reported in the literature in the presence of xenobiotic chemicals. 53 , 55 , 60 …”

Guiding Mineralization Co-Culture Discovery Using Bayesian Optimization

“…The most important ecological factor in bioaugmentation success has been postulated to be the invader’s ability to grow quickly and establish itself, reflected by the mineralization rate μ and the lag time λ, and not the total amount of accumulated mineralization A . Therefore, positive mineralization effects in pair-SFI co-cultures were defined as those increasing μ and decreasing λ, compared to the best-performing single-SFI co-culture, and vice versa for negative effects.…”

Individual-Based Modelling of Invasion in Bioaugmented Sand Filter Communities

“…These two parameters have been highlighted as key to the success of bioaugmentation strategies and are more strongly linked with both positive and negative mineralization effects than the other mineralization parameters [25].…”

“…The latter option is justified by considering that the parameters represent different biological attributes and different underlying processes [25]. This is most noticeable in their opposing effects on mineralization performance in particular; an increased parameter λ is considered a negative effect while an increased parameter µ is considered a positive effect.…”