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					                                   N-240: Chromium bio-immobilization at the Hanford 100H site
                                                                                         Comprehensive molecular analysis of microbial population dynamics.
                                                  Eoin Brodie1, Terry C. Hazen1, Boris Faybishenko1, Dominique Joyner1, Sharon Borglin1, Jeremy Hanlon1, Mark Conrad1, Tetsu Tokunaga1, Jiamin Wan1, Susan Hubbard1,
                                                                     Ken Williams1, John Peterson1, Mary Firestone1, Gary Andersen1, Todd DeSantis1, Philip E. Long2, Darrell R. Newcomer2, Anna Willett and Stephen Koenigsberg3
                                                                                                    .... 1University of California, Berkeley-Lawrence Berkeley National Lab .... 2Pacific Northwest National Lab .... 3Regenesis Ltd ....




Background                                                                                                                                             Clone library analysis                                                                                                                          Principal Components Analysis Microarrays                                                PLFA analysis
 The focus of these studies is to further understand the coupled hydraulic,                                                                                                                                                  Rarefaction    analysis     of     clone   libraries
 geochemical, and microbial conditions necessary to maximize Cr(VI) bioreduction                                                                                                                                             demonstrated that while diversity decreased                               PCA Group 1
 and minimize Cr(III) reoxidation in groundwater. Here we present data regarding                                                                                                                                             following HRC injection, 4 months later diversity                         These bacteria decline following HRC
                                                                                                                                                                                                                                                                                                       addition and continue to decline over time
 a comprehensive analysis of microbial populations during a field-scale treatability                                                                                                                                         was greater than the pre-injection groundwater
 study. We have combined a suite of molecular tools including 16S rDNA
 microarrays, clone libraries, stable isotope (13C) and PLFA analyses.                                                                                                                                                       None of the clone library rarefaction curves have
                                                                                                                                                                                                                             reached an asymptote indicating insufficient
Methods                                                                                                                                                                                                                      sampling of these communities                                                                                          Mostly gamma and beta-
                                                                                                                                                                                                                                                                                                                                                    proteobacteria
  At the Hanford 100H field site, two new wells were drilled and equipped —injection                                                                                                                                                                                                                                                                Sulfur oxidizers decline
  Well 699-96-45 and a monitoring and pumping Well 699-96-44. Samples were                                                                                                                                                                                                                                                                          Some iron oxidizers decline
  taken at intervals pre- and post-injection of a 13C labeled slow release polylactate                                                                 Figure 4. Rarefaction analysis of clone library diversity                                                                                                                                    Comamonadaceae (Leptothrix)
  compound (HRC) used to stimulate indigenous microbial populations of low initial                                                                                                                                                                                                                                                                  Some nitrate reducers decline          Figure 4. PLFA analysis of specific groundwater samples pre and post HRC injection. Numbers in
                                                                                                                                                                                                                                                                                                                                                                                           boxes indicate 13C ratio (per mil) detected in specific PLFA peaks.
  densities (<104 cells ml-1). For more information regarding site characteristics and
  HRC properties see poster N-230 (Hazen et al.). In addition to geochemical                                                                               Pre-HRC groundwater samples dominated                                                                                                                                                                                                 Carbon appears to take approx. 17 days to reach
  analyses, microscopic cell counts and stable isotope analyses, DNA and PLFAs                                                                             by Comamonadaceae, Pseudomonadaceae,                                                                                                                                                                                                  monitoring well 5 m from injection well and be
  were also extracted from filtered samples.                                                                                                               Moraxellaceae and also numerous                                                                                                             PCA Group 2                                                                               incorporated into biomass.
                                                                                                                                                           Oxalobacteraceae, and Sphingomonadaceae.                                                                                                                                                                                              General bacterial biomarkers indicate rapid enrichment
                                                                                                                                                                                                                                                                                                       These bacteria increase following HRC
  16S rRNA clone libraries were sequenced at JGI and assembled contigs checked                                                                             Following HRC injection Flavobacteriaceae                                                                                                   addition but return to background levels                                                  in 13C to a ratio greater than the spiked HRC ratio (15
                                                                                                                                                                                                                                                                                                       over time
  for sequence quality (Phred Q201) and chimeras using Bellerophon2 before                                                                                 increase sharply with Pseudomonadaceae                                                                                                                                                                                                per mil).
  phylogenetic analysis by tree construction in ARB3. Rarefaction analysis was                                                                             and Comamonadaceae remaining constant                                                                                                                                                                                                 Biomarkers for Flavobacteriaceae increased following
  carried out using DOTUR4.                                                                                                                                                                                                                                                                                                                         Bacteroidetes increase in response           injection but showed minimal enrichment .

  High Density 16S Microarray analysis was performed using a custom made
                                                                                                                                                           Diversity increases 4 months after HRC
                                                                                                                                                           injection with decreased abundance of
                                                                                                                                                                                                                                                                                                                                                    to HRC
                                                                                                                                                                                                                                                                                                                                                    Flavobacteriaceae do not typically    Discussion
  Affymetrix GeneChip5. The intensity (average difference) of OTUs with more than                                                                          Pseudomonadaceae, Comamonadaceae and                                                                                                                                                     oxidize lactate or acetate, but may    Chromate reduction was successful using slow release
  90% positive probes were compared at 3 time points pre- and post HRC addition.                                                                           Flavobacteriaceae, while Sphingomonadales,                                                                                                                                               utilize glycerol – an unlabeled        polylactate HRC and addition of a universally 13C labeled
                                                                                                                                                                                                                                    Figure 5. Distribution of sequences within clone libraries taken
  Hierarchical clustering was performed to observe large scale relationships and                                                                           Rhodobacterales, Caulobacterales,                                        during chromate bioremediation
                                                                                                                                                                                                                                                                                                                                                    component of the HRC compound          polylactate spike allowed tracking of carbon progress and
  principal components analysis of the most variable OTUs (top 10% standard                                                                                Chloroflexi and Legionellales all increase in                                                                                                                                            Different genera within                consumption. Following HRC injection most baseline
  deviation) was performed to identify dynamic organisms.                                                                                                  relative abundance                                                                                                                                                                       Comamonadaceae (Acidovorax)            microbes (many oligotrophs) declined. The 13C label in HRC
                                                                                                                                                                                                                                                                                                                                                                                           was rapidly metabolized and incorporated into most bacterial
Results                                                                                                                                                High Density DNA Microarray analysis                                                                                                                                                                                                biomarkers resulting in a 13C ratio that was substantially
                                                                                                                                                                                                                                                                                                                                                                                           greater than that of the spiked HRC spike reflecting the
Chromate analysis                                                                                                                                                                                                                                                                                      PCA Group 3                                                                         properties of the polylactate spike which was not
                                                                                                                                                                                                                                                                                                                                                                                           incorporated into the glycerol backbone of the HRC
                                                                                                                                                                                                                                                                                                       These bacteria decline following HRC
              HRC injection                               Pumping stopped                                         Compared to up-gradient                                                                                                                                                              addition but re-establish over time                                                 compound making it more readily soluble. An example of the
              1.E+00                                                                                              concentrations, chromate was                                                                                                                                                                                                                                             complementarity of the approaches used in this study can be
                                                                                                                  successfully removed from                     1                                                                                                                                                                                                                          seen with Flavobacteraceae. This organism was identified by
                                                                                                                  groundwater
                                                                  Upgradient Monitoring well

                                                                                                                                                                                                                                    Figure 7. Workflow schematic for 16S GeneChip analysis
                                                                                                                                                                                                                                                                                                                                                                                           clone and array analysis of increasing following HRC injection
              1.E-01                                                                                                                                            2                                                                                                                                                                                                                          however only array analysis detected this group of bacteria
 Cr(VI) ppm




                                                          Downgradient Monitoring well                            Chromate remained below
                                                                                                                  initial concentrations for over                                                                                                                                                                                                                                          pre-HRC addition. Furthermore, PLFA data indicate that
                                                                                                                                                                                                                                         Novel High Density Array contains
                                                                                                                  2 months following a single                                                                                                                                                                                                                                              compared to most bacteria in the sample, Flavobacteriaceae
              1.E-02                                                                                                                                                                                                                     500,000 probes for 16S rRNA genes
                                                                                                                  injection of HRC®                             3                                                                                                                                                                                                                          did not assimilate significant quantities of 13C despite their
                                                 Injection well                                                                                                                                                                          Each probe has corresponding                                                                               Many oligotrophic bacteria decline     increase in number. Flavobacteriaceae, typically do not
                                                                                                                  See poster N-230 for more                                                                                              mismatch probe (probe pairs)                                                                               with HRC injection                     utilize lactate or acetate but are capable of utilizing glycerol
              1.E-03
                                                                                                                  geochemical/geophysical data                                                                                                                                                                                                                                             which forms the backbone of the HRC compound and which
                                                                                                                                                                                                                                       9,000 sequence types (OTUs) are
                       8/2   8/9   8/16   8/23     8/30    9/6     9/13    9/20   9/27    10/4   10/11

                                                                                                                                                                                                                                                                                                                                                                                           was not labeled.
 Figure 2. Chromate concentration following HRC addition
                                                                                                   Microbial counts                                                                                                                    interrogated by a probe set containing at
                                                                                                                                                                                                                                    least 11 probe pairs                                                                                                                                  Conclusions
                                                                                                                                                                4                                                                                                                                      PCA Group 4                                                                         The combined approach of clone libraries (relative
                                                                                                                                                                                                                                         16S GeneChip has been validated                                                                                                                   abundance) and High Density Arrays (high resolution
                                                                                                                                                                                                                                         with air, water and soil samples                              These bacteria show a slight decline
                                                                                                                                                                                                                                                                                                                                                                                           prokaryotic dynamics) enabled accurate monitoring of
    Bacterial biomass was rapidly                                                                                                                                                                                                                                                                      following HRC but increase above
 stimulated following HRC® injection                                                                                                                                             Low                                         High                                                                      background levels with time                                                         population dynamics during this field trial. Array analysis has
                                                                                                                                                                                                                                                                                                                                                                                           been shown to correctly detect most bacteria, including whole
   Maximum biomass was observed 17                                                                                                                      Figure 8. Hierarchical clustering and heatmap plot of 16S GeneChip                                                                                                                          Increase in Legionellaceae,
                                                                                                                                                        analysis of microbial community sub-families detected during                                                                                                                                                                       phyla that are missed by clone analysis. Coupled with 13C
 days following HRC® addition                                                                                                                           chromate bioremediation. PCA groups are indicated by brackets.                                                                                                                              Chlamydiaceae and
                                                                                                                                                                                                                                                                                                                                                                                           PLFA, these methods were used successfully to follow carbon
                                                                                                                                                                                                                                                                                                                                                    Flexibacteriaceae
   Bacterial biomass began to decline                                                                                                                     Clustering of High Density Array data shows pre-HRC community clustering with                                                                                                                                                    assimilation and induced community shifts during remediation.
 approx. 3 months after HRC injection                                                                                                                  later 132 day post-HRC community indicating convergence                                                                                                                                                                             References
                                                                                                                                                                                                                                                                                                                                                                                           1.    Ewing et al. (1998). Genome Res. 8:175
                                                                                                                                                          A significant loss in diversity is suggested by large decreases in sub-family                                                                                                                                                    2.
                                                                                                                                                                                                                                                                                                                                                                                           3.
                                                                                                                                                                                                                                                                                                                                                                                                 Huber et al. (2004). Bioinformatics 20:2317
                                                                                                                                                                                                                                                                                                                                                                                                 Ludwig et al. (2004). Nucleic Acids Res. 32:1363.
                                                                                                                                                       relative abundance following HRC injection                                                                                                                                                                                          4.
                                                                                                                                                                                                                                                                                                                                                                                           5.
                                                                                                                                                                                                                                                                                                                                                                                                 Schloss and Handelsman (2005). Appl. Environ. Microbiol. 71:1501
                                                                                                                                                                                                                                                                                                                                                                                                 DeSantis et al. (2003). Bioinformatics. 19:1461
                                                                                                  Figure 3. Bacterial cell counts in monitoring well

                                                                                                                                                            Most dynamic sub-families indicated by PCA groups 1-4                                                                                                                                                                          Acknowledgements
                                                                                                                                                                                                                                                                                                                                                                                           Funded by Joint Natural and Accelerated Bioremediation (NABIR) Program, and the Office of Science
                                                                                                                                                                                                                                                                                                                                                                                           and Technology, Office of Environmental Management of DOE. Support of the field work by V.Gruol

				
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