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Šašinková D, Serbruyns L, Julinová M, FayyazBakhsh A, De Wilde B, Koutný M. Evaluation of the biodegradation of polymeric materials in the freshwater environment—An attempt to prolong and accelerate the biodegradation experiment. Polym Degrad Stab 2022. [DOI: 10.1016/j.polymdegradstab.2022.110085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Özel Duygan BD, Rey S, Leocata S, Baroux L, Seyfried M, van der Meer JR. Assessing Biodegradability of Chemical Compounds from Microbial Community Growth Using Flow Cytometry. mSystems 2021; 6:e01143-20. [PMID: 33563780 PMCID: PMC7883543 DOI: 10.1128/msystems.01143-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 01/15/2021] [Indexed: 11/20/2022] Open
Abstract
Compound biodegradability tests with natural microbial communities form an important keystone in the ecological assessment of chemicals. However, biodegradability tests are frequently limited by a singular focus either on the chemical and potential transformation products or on the individual microbial species degrading the compound. Here, we investigated a methodology to simultaneously analyze community compositional changes and biomass growth on dosed test compound from flow cytometry (FCM) data coupled to machine-learned cell type recognition. We quantified the growth of freshwater microbial communities on a range of carbon dosages of three readily biodegradable reference compounds, phenol, 1-octanol, and benzoate, in comparison to three fragrances, methyl jasmonate, myrcene, and musk xylene (as a nonbiodegradable control). Compound mass balances with between 0.1 to 10 mg C · liter-1 phenol or 1-octanol, inferred from cell numbers, parent compound analysis, and CO2 evolution, as well as use of 14C-labeled compounds, showed between 6 and 25% mg C · mg C-1 substrate incorporation into biomass within 2 to 4 days and 25 to 45% released as CO2 In contrast, similar dosage of methyl jasmonate and myrcene supported slower (4 to 10 days) and less (2.6 to 6.6% mg C · mg C-1 with 4.9 to 22% CO2) community growth. Community compositions inferred from machine-learned cell type recognition and 16S rRNA amplicon sequencing showed substrate- and concentration-dependent changes, with visible enrichment of microbial subgroups already at 0.1 mg C · liter-1 phenol and 1-octanol. In general, community compositions were similar at the start and after the stationary phase of the microbial growth, except at the highest used substrate concentrations of 100 to 1,000 mg C · liter-1 Flow cytometry cell counting coupled to deconvolution of communities into subgroups is thus suitable to infer biodegradability of organic chemicals, permitting biomass balances and near-real-time assessment of relevant subgroup changes.IMPORTANCE The manifold effects of potentially toxic compounds on microbial communities are often difficult to discern. Some compounds may be transformed or completely degraded by few or multiple strains in the community, whereas others may present inhibitory effects. In this study, we benchmark a new method based on machine-learned microbial cell recognition to rapidly follow dynamic changes in aquatic communities. We further determine productive biodegradation upon dosing of a number of well-known readily biodegradable tester compounds at a variety of concentrations. Microbial community growth was quantified using flow cytometry, and the multiple cell parameters measured were used in parallel to deconvolute the community on the basis of similarity to previously standardized cell types. Biodegradation was further confirmed by chemical analysis, showing how distinct changes in specific populations correlate to degradation. The method holds great promise for near-real-time community composition changes and deduction of compound biodegradation in natural microbial communities.
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Affiliation(s)
- B D Özel Duygan
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - S Rey
- Biotechnology and Natural Process Development Department, Firmenich SA, Geneva, Switzerland
| | - S Leocata
- Innovation in Analytical Chemistry Department, Firmenich SA, Geneva, Switzerland
| | - L Baroux
- Innovation in Analytical Chemistry Department, Firmenich SA, Geneva, Switzerland
| | - M Seyfried
- Biotechnology and Natural Process Development Department, Firmenich SA, Geneva, Switzerland
| | - J R van der Meer
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
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Timmer N, Gore D, Sanders D, Gouin T, Droge STJ. Toxicity mitigation and bioaccessibility of the cationic surfactant cetyltrimethylammonium bromide in a sorbent-modified biodegradation study. CHEMOSPHERE 2019; 222:461-468. [PMID: 30716549 DOI: 10.1016/j.chemosphere.2019.01.152] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 01/24/2019] [Accepted: 01/25/2019] [Indexed: 06/09/2023]
Abstract
Biodegradation potential of cationic surfactants may be hampered by inhibition of inoculum at concentrations required to accurately measure inorganic carbon. At >0.3 mg/L cetyltrimethylammonium bromide (CTAB) negatively impacted degradation of the reference compound aniline. We used silicon dioxide (SiO2) and illite as inorganic sorbents to mitigate toxicity of CTAB by lowering freely dissolved concentrations. In an OECD Headspace Test we tested whether 16.8 mg/L CTAB was readily biodegradable in presence of two concentrations of SiO2 and illite. SiO2 adsorbed 85% and 98% CTAB, resulting in concentrations of 2.5 and 0.34 mg/L, mineralized to CO2 >60% within 16 and 23 d, respectively. With 89% and 99% sorbed to illite, 60% mineralization was reached within 9 and 23 d, respectively. However, higher sorbent concentrations increased time needed to reach >60% mineralization. Thus, desorption kinetics likely decreased bioaccessibility. It is therefore essential to determine appropriate concentrations of mitigating sorbents to render a Headspace Test based on carbon analysis suitable to determine ready biodegradability of compounds which might inhibit inoculum. This would avoid use of expensive radiolabeled compounds. However, high sorbent concentrations can reduce bioaccessibility and limit degradation kinetics, particularly for relatively toxic substances that require strong mitigation.
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Affiliation(s)
- Niels Timmer
- Institute for Risk Assessment Sciences, Utrecht University, Utrecht 3508 TD, the Netherlands
| | - David Gore
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK
| | - David Sanders
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK
| | - Todd Gouin
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK
| | - Steven T J Droge
- Institute for Risk Assessment Sciences, Utrecht University, Utrecht 3508 TD, the Netherlands; Department Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94248, 1090 GE Amsterdam, the Netherlands.
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Besmer MD, Sigrist JA, Props R, Buysschaert B, Mao G, Boon N, Hammes F. Laboratory-Scale Simulation and Real-Time Tracking of a Microbial Contamination Event and Subsequent Shock-Chlorination in Drinking Water. Front Microbiol 2017; 8:1900. [PMID: 29085343 PMCID: PMC5649192 DOI: 10.3389/fmicb.2017.01900] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Accepted: 09/15/2017] [Indexed: 12/14/2022] Open
Abstract
Rapid contamination of drinking water in distribution and storage systems can occur due to pressure drop, backflow, cross-connections, accidents, and bio-terrorism. Small volumes of a concentrated contaminant (e.g., wastewater) can contaminate large volumes of water in a very short time with potentially severe negative health impacts. The technical limitations of conventional, cultivation-based microbial detection methods neither allow for timely detection of such contaminations, nor for the real-time monitoring of subsequent emergency remediation measures (e.g., shock-chlorination). Here we applied a newly developed continuous, ultra high-frequency flow cytometry approach to track a rapid pollution event and subsequent disinfection of drinking water in an 80-min laboratory scale simulation. We quantified total (TCC) and intact (ICC) cell concentrations as well as flow cytometric fingerprints in parallel in real-time with two different staining methods. The ingress of wastewater was detectable almost immediately (i.e., after 0.6% volume change), significantly changing TCC, ICC, and the flow cytometric fingerprint. Shock chlorination was rapid and detected in real time, causing membrane damage in the vast majority of bacteria (i.e., drop of ICC from more than 380 cells μl-1 to less than 30 cells μl-1 within 4 min). Both of these effects as well as the final wash-in of fresh tap water followed calculated predictions well. Detailed and highly quantitative tracking of microbial dynamics at very short time scales and for different characteristics (e.g., concentration, membrane integrity) is feasible. This opens up multiple possibilities for targeted investigation of a myriad of bacterial short-term dynamics (e.g., disinfection, growth, detachment, operational changes) both in laboratory-scale research and full-scale system investigations in practice.
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Affiliation(s)
- Michael D Besmer
- Drinking Water Microbiology Group, Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland.,Department of Environmental Systems Science, Institute of Biogeochemistry and Pollutant Dynamics, Zürich, Switzerland
| | - Jürg A Sigrist
- Drinking Water Microbiology Group, Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
| | - Ruben Props
- Center for Microbial Ecology and Technology, Ghent University, Ghent, Belgium
| | | | - Guannan Mao
- Drinking Water Microbiology Group, Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland.,Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, China
| | - Nico Boon
- Center for Microbial Ecology and Technology, Ghent University, Ghent, Belgium
| | - Frederik Hammes
- Drinking Water Microbiology Group, Department of Environmental Microbiology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
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Czechowska K, Reimmann C, van der Meer JR. Characterization of a MexAB-OprM efflux system necessary for productive metabolism of Pseudomonas azelaica HBP1 on 2-hydroxybiphenyl. Front Microbiol 2013; 4:203. [PMID: 23882265 PMCID: PMC3715732 DOI: 10.3389/fmicb.2013.00203] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 06/28/2013] [Indexed: 12/20/2022] Open
Abstract
Pseudomonas azelaica HBP1 is one of the few bacteria known to completely mineralize the biocide and toxic compound 2-hydroxybiphenyl (2-HBP), but the mechanisms of its tolerance to the toxicity are unknown. By transposon mutant analysis and screening for absence of growth on water saturating concentrations of 2-HBP (2.7 mM) we preferentially found insertions in three genes with high homology to the mexA, mexB, and oprM efflux system. Mutants could grow at 2-HBP concentrations below 100 μM but at lower growth rates than the wild-type. Exposure of the wild-type to increasing 2-HBP concentrations resulted in acute cell growth arrest and loss of membrane potential, to which the cells adapt after a few hours. By using ethidium bromide (EB) as proxy we could show that the mutants are unable to expel EB effectively. Inclusion of a 2-HBP reporter plasmid revealed that the wild-type combines efflux with metabolism at all 2-HBP concentrations, whereas the mutants cannot remove the compound and arrest metabolism at concentrations above 24 μM. The analysis thus showed the importance of the MexAB-OprM system for productive metabolism of 2-HBP.
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Affiliation(s)
- K Czechowska
- Department of Fundamental Microbiology, University of Lausanne, Bâtiment Biophore, Quartier UNIL-Sorge Lausanne, Switzerland
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