Characterization and Adaptation of Anaerobic Sludge Microbial Communities Exposed to Tetrabromobisphenol A

<div><p>The increasing occurrence of tetrabromobisphenol A (TBBPA) in the environment is raising questions about its potential ecological and human health impacts. TBBPA is microbially transformed under anaerobic conditions to bisphenol A (BPA). However, little is known about which taxa degrade TBBPA and the adaptation of microbial communities exposed to TBBPA. The objectives of this study were to characterize the effect of TBBPA on microbial community structure during the start-up phase of a bench-scale anaerobic sludge reactor, and identify taxa that may be associated with TBBPA degradation. TBBPA degradation was monitored using LC/MS-MS, and the microbial community was characterized using Ion Torrent sequencing and qPCR. TBBPA was nearly completely transformed to BPA <i>via</i> reductive debromination in 55 days. Anaerobic reactor performance was not negatively affected by the presence of TBBPA and the bulk of the microbial community did not experience significant shifts. Several taxa showed a positive response to TBBPA, suggesting they may be associated with TBBPA degradation. Some of these taxa had been previously identified as dehalogenating bacteria including <i>Dehalococcoides</i>, <i>Desulfovibrio</i>, <i>Propionibacterium</i>, and <i>Methylosinus</i> species, but most had not previously been identified as having dehalogenating capacities. This study is the first to provide in-depth information on the microbial dynamics of anaerobic microbial communities exposed to TBBPA.</p></div

Dynamics of methanogenic, archaeal, and bacterial populations.

<p>Quantification of the <i>mcrA</i> gene, archaeal 16S rDNA, and bacterial 16S rDNA as measured by qPCR. Efficiency and R² calculated from the standard curves were 89.7% and 0.911, 86.7% and 0.982, and 88.3% and 0.998, for the <i>mcrA</i>, archaeal, and bacterial 16S rDNA assays, respectively. Error bars represent the standard deviation from the mean. Different letters above bars indicate significant differences, according to a t-test (p ≤0.05), between days. If a bracket and an asterisk are present between two bars, it indicates that the two corresponding samples are significantly different, according to a t-test (p ≤0.05), performed within each day separately.</p

Relative abundance of some of the OTUs having higher abundances in TBBPA-spiked reactors at Day 28 or 55.

<p>Error bars represent the standard deviation from the mean. If a bracket and an asterisk are present between two bars, it indicates that the two corresponding samples are significantly different according to a t-test (p ≤0.05) performed for each day separately.</p

Weighted UniFrac matrix-based Principal Coordinate Analysis (PCoA) and Analysis of Similarity (ANOSIM) results.

<p>The percentage of variation explained for the x and y-axis are indicated on the graph. The table indicates the results of the ANOSIM analyses performed on the weighted UniFrac matrix generated. The null hypothesis (H₀) states that there is no difference between groups in terms of community composition. H₀ is rejected if p>0.05. An R-value close to 1 indicates an important differences between the groups tested, while an R-value close to 0 indicates a small difference between the groups tested in terms of community composition.</p

TBBPA degradation and formation of BPA.

<p>Concentration of TBBPA, BPA, and degradation by-products (i.e., 3,3',5-tribromobisphenol, 3,3'-dibromobisphenol and 3-bromobisphenol A) in metabolic (a) and co-metabolic (b) reactors overtime. Error bars represent standard deviation from the mean. TBBPA reductive debromination pathway is shown above the graphs.</p

List of the 32 OTUs extracted from our Ion Torrent dataset that were more abundant in TBBPA-spiked than in the control reactors.

<p>List of the 32 OTUs extracted from our Ion Torrent dataset that were more abundant in TBBPA-spiked than in the control reactors.</p

Identification of Flame Retardants in Polyurethane Foam Collected from Baby Products

With the phase-out of PentaBDE in 2004, alternative flame retardants are being used in polyurethane foam to meet flammability standards. However, insufficient information is available on the identity of the flame retardants currently in use. Baby products containing polyurethane foam must meet California state furniture flammability standards, which likely affects the use of flame retardants in baby products throughout the U.S. However, it is unclear which products contain flame retardants and at what concentrations. In this study we surveyed baby products containing polyurethane foam to investigate how often flame retardants were used in these products. Information on when the products were purchased and whether they contained a label indicating that the product meets requirements for a California flammability standard were recorded. When possible, we identified the flame retardants being used and their concentrations in the foam. Foam samples collected from 101 commonly used baby products were analyzed. Eighty samples contained an identifiable flame retardant additive, and all but one of these was either chlorinated or brominated. The most common flame retardant detected was tris(1,3-dichloroisopropyl) phosphate (TDCPP; detection frequency 36%), followed by components typically found in the Firemaster550 commercial mixture (detection frequency 17%). Five samples contained PBDE congeners commonly associated with PentaBDE, suggesting products with PentaBDE are still in-use. Two chlorinated organophosphate flame retardants (OPFRs) not previously documented in the environment were also identified, one of which is commercially sold as V6 (detection frequency 15%) and contains tris(2-chloroethyl) phosphate (TCEP) as an impurity. As an addition to this study, we used a portable X-ray fluorescence (XRF) analyzer to estimate the bromine and chlorine content of the foam and investigate whether XRF is a useful method for predicting the presence of halogenated flame retardant additives in these products. A significant correlation was observed for bromine; however, there was no significant relationship observed for chlorine. To the authors knowledge, this is the first study to report on flame retardants in baby products. In addition, we have identified two chlorinated OPFRs not previously documented in the environment or in consumer products. Based on exposure estimates conducted by the Consumer Product Safety Commission (CPSC), we predict that infants may receive greater exposure to TDCPP from these products compared to the average child or adult from upholstered furniture, all of which are higher than acceptable daily intake levels of TDCPP set by the CPSC. Future studies are therefore warranted to specifically measure infants exposure to these flame retardants from intimate contact with these products and to determine if there are any associated health concerns

Characteristics of sampled pediatric and adolescent patients (age 0 to 18 years).

1<p>For patients less than two years of age, severe immunosuppression was defined as an initial CD4 count less than 750 cells/mm³ or percentage less than 15%, moderate immunosuppression as an initial CD4 count of between 750 and 1500 cells/mm³ or percentage of between 15% and 25%, and no immunosuppression as an initial CD4 count of 1500 cells/mm³ or more, or percentage of 25% or more. For patients between two and five years of age, severe immunosuppression was defined as an initial CD4 count less than 500 cells/mm³ or percentage less than 15%, moderate immunosuppression as an initial CD4 count of between 500 and 1000 cells/mm³ or percentage of between 15% and 25%, and no immunosuppression as an initial CD4 count of 1000 cells/mm³ or more, or percentage of 25% or more. For patients between five years of age or older, severe immunosuppression was defined as an initial CD4 count less than 200 cells/mm³ or percentage less than 15%, moderate immunosuppression as an initial CD4 count of between 200 and 500 cells/mm³ or percentage of between 15% and 25%, and no immunosuppression as an initial CD4 count of 500 cells/mm³ or more, or percentage of 25% or more.</p>2<p>1 point assigned for each service received (screened for tuberculosis, adherence counseling at last visit, adherence measured by patient/caregiver self-report at last visit, ever prescribed co-trimoxazole, alive and not lost to follow-up with at least one CD4 count in the last six months, and weight documented in chart at patient's last visit, and 0 points assigned if the service was not received, for a total of 6 points. A high score was defined as having the median score or above (>4 points).</p

Kaplan-Meier loss to follow-up by quality indicator score (high vs. low).

<p>Kaplan-Meier loss to follow-up by quality indicator score (high vs. low).</p

Factors associated with mortality and loss to follow-up.

<p>HR, hazard ratio; AHR, adjusted hazard ratio; OR, odds ratio; AOR, adjusted odds ratio; CI, confidence interval; NS, not significant</p>1<p>For patients less than two years of age, severe immunosuppression was defined as an initial CD4 count less than 750 cells/mm³ or percentage less than 15%, moderate immunosuppression as an initial CD4 count of between 750 and 1500 cells/mm³ or percentage of between 15% and 25%, and no immunosuppression as an initial CD4 count of 1500 cells/mm³ or more, or percentage of 25% or more. For patients between two and five years of age, severe immunosuppression was defined as an initial CD4 count less than 500 cells/mm³ or percentage less than 15%, moderate immunosuppression as an initial CD4 count of between 500 and 1000 cells/mm³ or percentage of between 15% and 25%, and no immunosuppression as an initial CD4 count of 1000 cells/mm³ or more, or percentage of 25% or more. For patients between five years of age or older, severe immunosuppression was defined as an initial CD4 count less than 200 cells/mm³ or percentage less than 15%, moderate immunosuppression as an initial CD4 count of between 200 and 500 cells/mm³ or percentage of between 15% and 25%, and no immunosuppression as an initial CD4 count of 500 cells/mm³ or more, or percentage of 25% or more.</p>2<p>1 point assigned for each service received (screened for tuberculosis, adherence counseling at last visit, adherence measured by patient/caregiver self-report at last visit, ever prescribed co-trimoxazole, alive and not lost to follow-up with at least one CD4 count in the last six months, and weight documented in chart at patient's last visit and 0 points assigned if the service was not received, for a total of 6 points. A high score was defined as having the median score or above (>4 points).</p