Aerobic biodegradation of trichloroethylene and phenol co-contaminants in groundwater by a bacterial community using hydrogen peroxide as the sole oxygen source

Abstract

Trichloroethylene (TCE) and phenol were often found together as co-contaminants in the groundwater of industrial contaminated sites. An effective method to remove TCE was aerobic biodegradation by co-metabolism using phenol as growth substrates. However, the aerobic biodegradation process was easily limited by low concentration of dissolved oxygen (DO) in groundwater, and DO was improved by air blast technique with difficulty. This study enriched a bacterial community using hydrogen peroxide (H2O2) as the sole oxygen source to aerobically degrade TCE by co-metabolism with phenol in groundwater. The enriched cultures were acclimatized to 2-8 mM H2O2 which induced catalase, superoxide dismutase and peroxidase to decompose H2O2 to release O2 and reduce the toxicity. The bacterial community could degrade 120 mg/L TCE within 12 days by using 8 mM H2O2 as the optimum concentration, and the TCE degradation efficiency reached up to 80.6%. 16S rRNA gene cloning and sequencing showed that Bordetella, Stenotrophomonas sp., Sinorhizobium sp., Variovorax sp. and Sphingobium sp. were the dominant species in the enrichments, which were clustered in three phyla: Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria. Polymerase chain reaction detection proved that phenol hydroxylase (Lph) gene was involved in the co-metabolic degradation of phenol and TCE, which indicated that hydroxylase might catalyse the epoxidation of TCE to form the unstable molecule TCE-epoxide. The findings are significant for understanding the mechanism of biodegradation of TCE and phenol co-contamination and helpful for the potential applications of an aerobic bioremediation in situ the contaminated sites.

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

“…Instead, the key group was the Gammaproteobacteria, irrespective of the presence or absence of TCE. Members of Gammaproteobacterial groups such as Pseudomonas, Bacillus, Stenotrophomonas and Acinetobacter sp are associated with TCE enrichment cultures or contaminated sites [45,46]. Alongside, alpha-and betaproteobacteria groups (also detected in this study), these organisms are believed to be involved in the co-metabolism of the TCE contaminant [46].…”

Bioremediation of trichloroethylene‐polluted groundwater using emulsified castor oil for slow carbon release and acidification control

“…Aziz et al (2020) and Li et al (2015) reported that Variovorax sp. could biodegrade TCE with phenol being used as a carbon substrate.…”

Natural attenuation model and biodegradation for 1,1,1-trichloroethane contaminant in shallow groundwater

“…Total DNA was extracted from each sample by the bead beating technique (BioSpec, Shanghai, China) using the kit UltraClean DNA Isolation (Mo Bio Laboratories, BIOzym, Landgraaf, Netherlands). Polymerase chain reaction (PCR) amplification was implemented with bacterial primers 27F and 1492R ( Li et al, 2015 ), using a 25 μL reaction mixture containing the template 0.5 μL, each primer (10 mmol/L) 0.5 μL, TaqMix 12.5 μL, and ddH 2 O 11 μL. PCR was performed under the cycling conditions described as follows: initial denaturation at 94°C for 5 min, 25 cycles of denaturation at 94°C for 1 min, annealing at 50°C for 30 s, and extension at 72°C for 1 min, then re-extension at 72°C for 10 min.…”