Browse all Channels
  1. Companies
  2. Regenesis
  3. Articles
  4. Differential Stimulation of Haloreduction by Carbon Addition to ...

Differential Stimulation of Haloreduction by Carbon Addition to Subsurface Soils (PDF)

0
- By: , , ,

Courtesy of Regenesis

Highly substituted ethenes such as PCE and TCE are susceptible to microbial reductive dehalogenation and halorespiration under anaerobic conditions. The objective of this study was to evaluate whether soil from a bulk aerobic aquifer, historically contaminated with chlorinated ethenes (CEs), could be made anaerobic by carbon source addition to enhance haloreduction, and to evaluate how the addition of these different carbon sources affects microbial community structure.

We hypothesized that sulfate-reducing bacteria (SRBs) were responsible for dechlorination in this study because of the near-shore location of the site. Using soil and water from the aquifer, microcosms were constructed to examine the effects of various electron donors on reductive dehalogenation. Six electron donor treatments were compared including acetate, propionate, lactate, ethanol, vegetable oil (soy oil), and hydrogen release compound (HRC, Regenesis).

An SRB-inhibited control (using Na2MoO4) and an abiotic control (using NaN3) were included with each treatment. Concentrations of CEs in the aqueous phase were measured via headspace analysis and GC/MS detection. With addition of excess electron donor, reduction of PCE and TCE to cis-1,2-dichloroethene (cis-1,2-DCE) occurred in the microcosms.
When acetate, propionate, ethanol, or HRCwere added, PCE and TCE concentrations quickly decreased (~20 days) and cis-1,2-DCE was formed. With the lactate and vegetable oil treatments, cis-1,2-DCE was formed only after a considerable lag period (~60 days). For the lactate, ethanol, vegetable oil, and HRCtreatments, PCE and TCE reduction was observed
neither in the abiotic nor in the SRB-inhibited control. This finding suggests that SRBs are involved in dechlorination with those carbon sources. In the acetate and propionate treatments, reduction of PCE and TCE to cis-1,2-DCE again was not observed in the abiotic control but was observed in the SRB-inhibited control. This suggests that reductive dehalogenation using acetate or propionate as a carbon source is not contingent on the presence of sulfate-reducing
microorganisms. On the other hand, since reduction of CEs still occurred in the non-inhibited microcosms, other microbial groups were possibly stimulated.

In our effort to understand the key microbial groups required for reductive dehalogenation and monitor structural changes in microbial community as a response to the addition of different carbon sources, DNA profiles based on Terminal Restriction Fragment Length Polymorphism (T-RFLP) analysis were compared. As expected, different bacterial community profiles were obtained depending on carbon source. When sulfate reduction was inhibited or yeast extract was added, a dramatic change in the microbial community structure occurred.

Related articles

  • Norwegian study on microbial source tracking for water quality control and pollution removal in ...

    This study describes the first Norwegian microbial source tracking (MST) approach for water quality control and pollution removal from catchment run-off in a nature-based treatment system (NBTS) with a constructed wetland. The applied MST tools combined microbial analyses and molecular tests to detect and define the source(s) and dominant origin(s) of faecal water contamination. Faecal indicator bacteria Escherichia coli and host-specific Bacteroidales 16 s rRNA gene markers have been employed. The study revealed...

  • Bacterial biofilms formed in arsenic-containing water: bacterial community characterization

    We have analyzed the structure and diversity of bacterial biofilms formed on different water distribution materials in the absence and in the presence of 5 mg/L of arsenic(V). Three commercial metals (cast iron, zinc and copper) and polypropylene were used as substrata for biofilm formation. Biofilms were observed using scanning electron microscopy. Microbial ecology techniques (DNA amplification by polymerase chain reaction and denaturing gradient gel electrophoresis) were applied to study the bacterial community...

  • Characterisation of L. monocytogenes strains isolated from salad vegetables

    Seventy–one strains of L. monocytogenes isolated from raw salad vegetables consumed in the minimally processed state in Malaysia were characterised by serotyping, random amplified polymorphic DNA–polymerase chain reaction analysis (RAPD–PCR) and antimicrobial susceptibility testing. Based on serotyping, only one strain belonged to serotype 4 while the rest were from serotype 1. RAPD–PCR typing was carried out using two primers, i.e., OPAR–8 and GEN 1–50–09. Based on RAPD–PCR fingerprinting, the strains could be...

  • Monitoring of three drinking water treatment plants using flow cytometry

    A 4-month sampling campaign has been conducted for the monitoring of three drinking water treatment plants using flow cytometry and culture-based methods to provide information related to changes in bacterial concentration according to treatments. Flow cytometry is a fast and user-friendly technique enabling bacteria quantification and viability assessment in less than 1 hour. Specific profiles regarding log-reduction of total bacteria were obtained for each treatment plant. Chlorination appeared to be the most...

  • Precellys application focus forensic - case study

    Forensic laboratories working with hard samples such as hair [1, 2J, bone [3], teeth, skin, etc. experience difficulties with DNA extraction due to the high energy needed to grind these tissues. Moreover, biological evidence is available in small quantities and the current techniques used do not provide high quality results. The Precellys homogenizers provides high speed sample disruption based on bead-beating for the extraction of DNA, proteins, and drugs [1, 2, 3J within minutes with high reproducibility and no...

Customer comments

No comments were found for Differential Stimulation of Haloreduction by Carbon Addition to Subsurface Soils (PDF). Be the first to comment!