In situ TCE degradation mediated by complex dehalorespiring communities during biostimulation processes

Abstract

Summary The bioremediation of chloroethene contaminants in groundwater polluted systems is still a serious environmental challenge. Many previous studies have shown that cooperation of several dechlorinators is crucial for complete dechlorination of trichloroethene to ethene. In the present study, we used an explorative functional DNA microarray (DechloArray) to examine the composition of specific functional genes in groundwater samples in which chloroethene bioremediation was enhanced by delivery of hydrogen‐releasing compounds. Our results demonstrate for the first time that complete biodegradation occurs through spatial and temporal variations of a wide diversity of dehalorespiring populations involving both Sulfurospirillum, Dehalobacter, Desulfitobacterium, Geobacter and Dehalococcoides genera. Sulfurospirillum appears to be the most active in the highly contaminated source zone, while Geobacter was only detected in the slightly contaminated downstream zone. The concomitant detection of both bvcA and vcrA genes suggests that at least two different Dehalococcoides species are probably responsible for the dechlorination of dichloroethenes and vinyl chloride to ethene. These species were not detected on sites where cis‐dichloroethene accumulation was observed. These results support the notion that monitoring dechlorinators by the presence of specific functional biomarkers using a powerful tool such as DechloArray will be useful for surveying the efficiency of bioremediation strategies.

The change of microbial community from chlorinated solvent-contaminated groundwater after biostimulation using the metagenome analysis

“…Geobacter is able to degrade PCE/TCE into cDCE under anaerobic condition, and was detected in TCE-contaminated water [5,21]. Based on the presence of the above indigenous bacteria, we could infer that these bacteria would be involved in biodegrading PCE/TCE after biostimulation irrespective of the amounts of these bacteria increased or decreased.…”

“…The biostimulation technology involves the addition of electron donors or highly fermentable nutrients directly to the groundwater, to improve the complete dechlorination by indigenous microorganisms [5]. Some products (for example, soybean oil and other food-grade edible oils) containing significant amounts of organic carbons can be provided for the enhancement of the reductive dechlorination of chlorinated solvents [6][7][8][9][10].…”

Exploiting the intrinsic microbial degradative potential for field-based in situ dechlorination of trichloroethene contaminated groundwater

“…However, some of the results were based on qPCR detection indicating only the presence or absence of the classical dechlorinator, Dhc. There are very few reports of NGS based dechlorinating microbial community studies [26,27], with limited reports of NGS based in-situ remediation study [28]. Fundamental knowledge of microbial community structure, dynamics and functionality is important for predicting contaminant degradation patterns and deciding which bioremediation strategy to implement [20].…”

Inferring community dynamics of organohalide-respiring bacteria in chemostats by covariance ofrdhAgene abundance

“…In this study, we exploited this linkage of specific rdh genes among each other and to the Dhc organismal core to define Dhc strains. D. mccartyi populations have been monitored in the past based on their reductive dehalogenase genes through quantitative PCR (qPCR; Holmes et al ., ), clone libraries (Futamata et al ., ), and DNA microarrays (Taş et al ., ; Dugat‐Bony et al ., , ). However, such approaches carry no information on linkage of important functional genes to an organism's core and therefore lack the power to comprehensively define strains within a population.…”