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Kademoglou K, Williams AC, Collins CD. Bioaccessibility of PBDEs present in indoor dust: A novel dialysis membrane method with a Tenax TA® absorption sink. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 621:1-8. [PMID: 29175617 DOI: 10.1016/j.scitotenv.2017.11.097] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 10/26/2017] [Accepted: 11/08/2017] [Indexed: 06/07/2023]
Abstract
Human uptake of flame retardants (FRs) such as polybrominated diphenyl ethers (PBDEs) via indoor dust ingestion is commonly considered as 100% bioaccessible, leading to potential risk overestimation. Here, we present a novel in vitro colon-extended physiologically-based extraction test (CE-PBET) with Tenax TA® as an absorptive "sink" capable to enhance PBDE gut bioaccessibility. A cellulose-based dialysis membrane (MW cut-off 3.5kDa) with high pH and temperature tolerance was used to encapsulate Tenax TA®, facilitating efficient physical separation between the absorbent and the dust, while minimizing re-absorption of the ingested PBDEs to the dust particles. As a proof of concept, PBDE-spiked indoor dust samples (n=3) were tested under four different conditions; without any Tenax TA® addition (control) and with three different Tenax TA® loadings (i.e. 0.25, 0.5 or 0.75g). Our results show that in order to maintain a constant sorptive gradient for the low MW PBDEs, 0.5g of Tenax TA® are required in CE-PBET. Tenax TA® inclusion (0.5g) resulted in 40% gut bioaccessibility for BDE153 and BDE183, whereas greater bioaccessibility values were seen for less hydrophobic PBDEs such as BDE28 and BDE47 (~60%). When tested using SRM 2585 (n=3), our new Tenax TA® method did not present any statistically significant effect (p>0.05) between non-spiked and PBDE-spiked SRM 2585 treatments. Our study describes an efficient method where due to the sophisticated design, Tenax TA® recovery and subsequent bioaccessibility determination can be simply and reliably achieved.
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Affiliation(s)
- Katerina Kademoglou
- Soil Research Centre, Department of Geography and Environmental Science, University of Reading, Whiteknights Campus, RG6 6DW Reading, UK.
| | - Adrian C Williams
- School of Pharmacy, University of Reading, Whiteknights Campus, RG6 6AD Reading, UK
| | - Chris D Collins
- Soil Research Centre, Department of Geography and Environmental Science, University of Reading, Whiteknights Campus, RG6 6DW Reading, UK.
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2
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Pollard PC. Bacterial activity in plant (Schoenoplectus validus) biofilms of constructed wetlands. WATER RESEARCH 2010; 44:5939-5948. [PMID: 20723964 DOI: 10.1016/j.watres.2010.07.047] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 07/08/2010] [Accepted: 07/14/2010] [Indexed: 05/29/2023]
Abstract
Biofilm-bacterial communities have been exploited in the treatment of wastewater in 'fixed-film' processes. Our understanding of biofilm dynamics requires a quantitative knowledge of bacterial growth-kinetics in these microenvironments. The aim of this paper was to apply the thymidine assay to quantify bacterial growth without disturbing the biofilm on the surfaces of emergent macrophytes (Schoenoplectus validus) of a constructed wetland. The isotope was rapidly and efficiently taken-up and incorporated into dividing biofilm-bacteria. Isotope diffusion into the biofilm did not limit the growth rate measurement. Isotope dilution was inhibited at >12 μM thymidine. Biofilm-bacterial biomass and growth rates were not correlated to the plant surface area (r(2) < 0.02). The measurements of in situ biofilm-bacterial growth rates both displayed, and accommodated, the inherent heterogeneity of the complex wetland ecosystem. Biofilm-bacterial respiratory activities, measured using the redox dye CTC, and growth rates were measured simultaneously. The dye did not interfere with bacterial growth. Biofilm-bacterial specific growth rates ranged from 1.4 ± 0.6 d(-1) to 3.3 ± 1.3 d(-1). In the constructed wetlands of this study biofilm-bacterial specific growth rates, compared to those of natural ecosystems, could be markedly improved through changes in wetland design that increased bacterial respiration while minimising biofilm growth.
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Affiliation(s)
- Peter C Pollard
- Australian Rivers Institute, Griffith University, Q 4111 Australia.
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Pollard PC. A quantitative measure of nitrifying bacterial growth. WATER RESEARCH 2006; 40:1569-76. [PMID: 16603221 DOI: 10.1016/j.watres.2006.02.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2005] [Revised: 02/13/2006] [Accepted: 02/14/2006] [Indexed: 05/08/2023]
Abstract
Nitrifying bacteria convert ammonia (NH3) to nitrate (NO3-) in a nitrification reaction. Methods to quantitatively separate the growth rate of these important bacterial populations from that of the dominant heterotrophic bacteria are important to our understanding of the nitrification process. The changing concentration of ammonia is often used as an indirect measure of nitrification but ammonification processes generate ammonia and confound this approach while heterotrophs remove nitrate via denitrification. Molecular probe methods can tell us what proportion of the microbial community is nitrifying bacteria but not their growth rate. The technique proposed here was able to quantify the growth rate of the nitrifying bacterial populations amidst complex ecological processes. The method incubates [methyl-3H] thymidine with water samples in the presence and absence of an inhibitor of nitrification-thiourea. The radioactively labeled DNA in the growing bacteria was extracted. The rate of incorporation of the label into the dividing bacterial DNA was used to determine bacterial growth rate. Total bacterial community growth rates in full-scale and pilot-scale fixed-film nitrifying reactors and an activated sludge reactor were 2.1 x 10(8), 4.1 x 10(8) and 0.4 x 10(8)cell ml(-1)d(-1), respectively; the growth rate of autotrophic-nitrifying bacteria was 0.7 x 10(8), 2.6 x 10(8) and 0.01 x 10(8)cell ml(-1)d(-1), respectively. Autotrophic-nitrifying bacteria contributed 30% and 60% of the total bacterial community growth rate in the nitrifying reactors whereas only 2% was observed in the activated sludge reactor that was not designed to nitrify. The rates of ammonia loss from the nitrifying reactors corresponded to the rate of growth of the nitrifying bacteria. This method has the potential to more often identify factors that enhance or limit nitrifying processes in both engineered and natural aquatic environments.
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Affiliation(s)
- Peter C Pollard
- Centre for Riverine Landscapes, School of Engineering, Griffith University, Nathan campus, Queensland 4111, Australia.
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Guthrie JN, Moriarty DJ, Blackall LL. DNA extraction from coral reef sediment bacteria for the polymerase chain reaction. J Microbiol Methods 2000; 43:73-80. [PMID: 11121605 DOI: 10.1016/s0167-7012(00)00207-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A rapid and effective method for the direct extraction of high molecular weight amplifiable DNA from two coral reef sediments was developed. DNA was amplified by the polymerase chain reaction (PCR) using 16S rDNA specific primers. The amplicons were digested with HaeIII, HinP1I and MspI and separated using polyacrylamide gel electrophoresis and silver staining. The resulting amplified ribosomal DNA restriction analysis (ARDRA) patterns were used as a fingerprint to discern differences between the coral reef sediment samples. Results indicated that ARDRA is an effective method for determining differences within the bacterial community amongst different environmental samples.
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Affiliation(s)
- J N Guthrie
- Centre for Bacterial Diversity and Identification, Department of Microbiology, The University of Queensland, 4072, Brisbane, Australia.
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Garet M, Moriarty D. Acid extraction of tritium label from bacterial DNA in clay sediment. J Microbiol Methods 1996. [DOI: 10.1016/0167-7012(95)00071-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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6
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Tuominen L. Comparison of leucine uptake methods and a thymidine incorporation method for measuring bacterial activity in sediment. J Microbiol Methods 1995. [DOI: 10.1016/0167-7012(95)00062-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Kairesalo T, Tuominen L, Hartikainen H, Rankinen K. The role of bacteria in the nutrient exchange between sediment and water in a flow-through system. MICROBIAL ECOLOGY 1995; 29:129-144. [PMID: 24186719 DOI: 10.1007/bf00167160] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/1994] [Revised: 07/09/1994] [Indexed: 06/02/2023]
Abstract
The contribution of bacteria to phosphorus (P) and nitrogen (N ) release from, or retention in, sediment was studied in a flow-through system. "Live" and formaldehyde-"killed" sediment communities were incubated in 25-liter bottles with a continuous flow of P- or P + N-enriched water. Sediment bacteria in the killed communities were inhibited by adding formaldehyde (final concentration 0.04% v/v) to the sediment before the start of the experiment. Bacterial activity in the live sediments measured with [(3)H]thymidine and [(14)C]leucine incorporation techniques did not change essentially during the experiment period (7-8 days). Chemical mechanisms were found to be of principal importance in PO4-P retention in the sediment. In the live samples, the net retention of PO4-P was lower than in the killed samples, which was likely due to the reduced O2 conditions in the sediment as a consequence of bacterial mineralization. In total P exchange, however, bacteria increased the retention rate by recycling dissolved organic P in the sediment. In the live communities the retention of N was very efficient, and all the introduced NH4 -N and NO3-N was immobilized by sediment bacteria. Nitrogen enrichment, however, did not alter the P exchange rates. The gradual emergence of bacterial activity (and grazing) in the killed communities, subsequent to the dilution of formaldehyde concentration, enhanced the release of PO4-P and NH4-N from sediment.
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Affiliation(s)
- T Kairesalo
- The Environmental Unit, University of Helsinki, Niemenkatu 73, FIN-15210, Lahti, Finland
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Robarts RD, Zohary T. Fact or Fiction-Bacterial Growth Rates and Production as Determined by [methyl-3H]-Thymidine? ADVANCES IN MICROBIAL ECOLOGY 1993. [DOI: 10.1007/978-1-4615-2858-6_9] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Tibbles BJ, Davis CL, Harris JM, Lucas MI. Estimates of bacterial productivity in marine sediments and water from a temperate saltmarsh lagoon. MICROBIAL ECOLOGY 1992; 23:195-209. [PMID: 24192931 DOI: 10.1007/bf00164096] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/1991] [Revised: 01/03/1992] [Indexed: 06/02/2023]
Abstract
Tritiated thymidine incorporation (TTI) into DNA was used to estimate bacterial productivity in sediment and water samples from two sites in Langebaan Lagoon, South Africa. Routine analysis of isotope dilution showed seasonal variations of approximately threefold in the thymidine precursor pool sizes for bacterial assemblages from each site. Dual label incorporation of [(3)H]-thymidine and (14)C-leucine into DNA and protein, respectively, showed that pelagic but not sediment assemblages were in a balanced state of growth during TTI. This is the first report of dual label measurements of bacterial production in sediments. Sediments supported bacterial productivities that exceeded those in the water column by factors from five- to 950-fold, whereas bacterial abundance supported by sediments exceeded that in the water column by more than 3 orders of magnitude. Estimates of bacterial productivities in sediments were coincident with levels of organic content in sediments, but not with bacterial abundance. Measurements of TTI activity for 5 different benthic microhabitats at one lagoon site showed highest activity associated with seagrass beds (2.11 ± 0.84 nmol thymidine hours(-1) g-1 dry weight), whereas activities decreased with depth (0.46 ± 0.21 nmol thymidine hours(-1) g(-I) dry weight) below sediment surface.
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Affiliation(s)
- B J Tibbles
- Marine Biology Research Institute, Department of Zoology, University of Cape Town, Rondebosch 7700, South Africa
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Jeffrey WH, Paul JH, Cazares LH, Deflaun MF, David AW. Correlation of nonspecific macromolecular labeling with environmental parameters during [(3)H]Thymidine incorporation in the waters of southwest florida. MICROBIAL ECOLOGY 1990; 20:21-35. [PMID: 24193961 DOI: 10.1007/bf02543864] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/1990] [Revised: 07/03/1990] [Indexed: 06/02/2023]
Abstract
During routine [(3)H]thymidine incorporation measurements of environmental samples, significant amounts of radioactivity are often incorporated into macromolecules other than DNA. Although the percentage of nonspecific labeling varies both temporally and spatially, the cause(s) of these variations remain unknown. Correlations between the percent incorporated radioactivity in DNA and a variety of experimental and environmental parameters measured in the Alfia River, Crystal River, Medard Reservoir, and Bayboro Harbor were examined. The amount of radioactivity incorporated into DNA ranged from 6 to 95% ([Formula: see text]; n=121). Nonspecific labeling began immediately upon the addition of [(3)H]thymidine and was linear over time. Labeling patterns were independent of both the amount of thymidine added and cell-size fraction. A two year study of Bayboro Harbor indicated no conclusive relationship between nonspecific labeling and seasonality. The amount of radioactivity incorporated into DNA was inversely correlated with total rates of thymidine incorporation and a strong diurnal pattern was observed in the Crystal River. No consistent relationship was observed between labeling patterns and primary productivity, chlorophylla, particulate DNA, dissolved DNA, bacterial cell numbers, temperature, salinity, and dissolved organic carbon. The only relationship with dissolved inorganic nutrients (N and P) occurred in the Crystal River. In this phosphate limited river, the percent of radioactivity incorporated into DNA was positively correlated with phosphate concentrations. These results indicate that nonspecific labeling is not dependent on any one parameter but may be a function of many interacting environmental factors or a function of the specific ambient bacterial population.
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Affiliation(s)
- W H Jeffrey
- Department of Marine Science, University of South Florida, 33701, St. Petersburg, Florida, USA
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Moriarty D, Pollard P. Effects of radioactive labelling of macromolecules, disturbance of bacteria and adsorption of thymidine to sediment on the determination of bacterial growth rates in sediment with tritiated thymidine. J Microbiol Methods 1990. [DOI: 10.1016/0167-7012(90)90013-v] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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12
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6 Techniques for Estimating Bacterial Growth Rates and Production of Biomass in Aquatic Environments. METHODS IN MICROBIOLOGY 1990. [DOI: 10.1016/s0580-9517(08)70243-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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13
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Lipid composition and metabolic activities of benthic near-shore microbial communities of Arthur Harbor, antarctic peninsula: Comparisons with McMurdo Sound. Polar Biol 1989. [DOI: 10.1007/bf00261036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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