The Experts below are selected from a list of 15246 Experts worldwide ranked by ideXlab platform

Wen Tso Liu - One of the best experts on this subject based on the ideXlab platform.

  • Core-satellite populations and seasonality of water meter Biofilms in a metropolitan drinking water distribution system
    The ISME Journal, 2016
    Co-Authors: Fangqiong Ling, Chiachi Hwang, Mark W Lechevallier, Gary L Andersen, Wen Tso Liu
    Abstract:

    Drinking water distribution systems (DWDSs) harbor the microorganisms in Biofilms and suspended communities, yet the diversity and spatiotemporal distribution have been studied mainly in the suspended communities. This study examined the diversity of Biofilms in an urban DWDS, its relationship with suspended communities and its dynamics. The studied DWDS in Urbana, Illinois received conventionally treated and disinfected water sourced from the groundwater. Over a 2-year span, biomass were sampled from household water meters ( n =213) and tap water ( n =20) to represent Biofilm and suspended communities, respectively. A positive correlation between operational taxonomic unit (OTU) abundance and occupancy was observed. Examined under a ‘core-satellite’ model, the Biofilm Community comprised 31 core populations that encompassed 76.7% of total 16 S rRNA gene pyrosequences. The Biofilm communities shared with the suspended Community highly abundant and prevalent OTUs, which related to methano-/methylotrophs (i.e., Methylophilaceae and Methylococcaceae ) and aerobic heterotrophs ( Sphingomonadaceae and Comamonadaceae ), yet differed by specific core populations and lower diversity and evenness. Multivariate tests indicated seasonality as the main contributor to Community structure variation. This pattern was resilient to annual change and correlated to the cyclic fluctuations of core populations. The findings of a distinctive Biofilm Community assemblage and methano-/methyltrophic primary production provide critical insights for developing more targeted water quality monitoring programs and treatment strategies for groundwater-sourced drinking water systems.

  • impact of silver nanoparticles on natural marine Biofilm bacteria
    Chemosphere, 2011
    Co-Authors: Julia Fabrega, Wen Tso Liu, Rui Zhang, Joanna C Renshaw, Jamie R Lead
    Abstract:

    Abstract There has been a recent increase in the use of silver nanoparticles (Ag NPs) in a wide range of consumer products due to their highly effective antimicrobial properties. However, Ag NPs give cause for concern since their wide use makes them likely to be released into aquatic ecosystems and potentially affect natural bacterial communities. In this study marine Biofilms were grown in situ in a coastal site (Singapore Harbour) and exposed in the laboratory for a further 24 h to 0–2000 μg L −1 of well characterised Ag NPs. Increasing concentrations of Ag NPs caused a significant decrease in Biofilm volume and biomass, and Ag uptake by Biofilms per unit of volume was also dependent on concentration. Terminal fragment length polymorphisms and subsequent cluster and phylogenetic analysis showed the presence of major bacterial groups in Biofilms irrespective of treatment with Ag NPs. This implies that even at the highest concentrations studied these taxonomic groups were not displaced. Nevertheless, Biofilm succession was impeded on Ag NP treated Biofilms, affecting the relative abundance of major bacterial groups in the Biofilm Community, with potential longer term effects on Biofilm development and function.

  • Community structure analysis of reverse osmosis membrane Biofilms and the significance of Rhizobiales bacteria in biofouling.
    Environmental Science & Technology, 2007
    Co-Authors: Chee Meng Pang, Wen Tso Liu
    Abstract:

    The Biofilm Community structure of a biofouled reverse osmosis (RO) membrane was examined using a polyphasic approach, and the dominant phylotypes retrieved were related to the order Rhizobiales, a group of bacteria that is hitherto not implicated in membrane biofouling. A comparison with two other membrane Biofilms using T-RFLP fingerprinting also revealed the dominance of Rhizobiales organisms. When pure culture RO Biofilm isolates were cultivated aerobically in BIOLOG microplates, most Rhizobiales were metabolically versatile in their choice of carbon substrates. Nitrate reduction was observed in five RO isolates related to Castellaniella, Ochrobactrum, Stenotrophomonas, and Xanthobacter. Many of the key Rhizobiales genera including Bosea, Ochrobactrum, Shinella, and Rhodopseudomonas were detected by PCR to contain the nirK gene responsible for nitrite reductase activity. These findings suggest that Rhizobiales organisms are ecologically significant in membrane Biofilm communities under both aerobic and anoxic conditions and may be responsible for biofouling in membrane separation systems.

Zhaojing Zhang - One of the best experts on this subject based on the ideXlab platform.

  • florfenicol restructured the microbial interaction network for wastewater treatment by microbial electrolysis cells
    Environmental Research, 2020
    Co-Authors: Kai Feng, Zhaojing Zhang, Aijie Wang, Yuanyuan Qu, S X Li, Shang Wang, Ye Deng
    Abstract:

    Abstract To investigate the influence of antibiotics on microbial interactions in a Biofilm Community, we set up eight replicate reactors of microbial electrolysis cell (MEC) and applied a broad-spectrum antibiotic florfenical (FLO) as an environmental disturbance. According to the results, exposure to FLO resulted in degradation of reactor performance. The MEC could also rebound back to the comparably stable state at a certain time which exhibited a great resilience ability in response to antibiotic disturbance. The FLO perturbation showed a significant influence on the electroactive Biofilms (EABs) with a distinct reformation of the Community structure. Network analysis revealed that microbial interactions in the Biofilms after full recovery became much closer, with a rapid increase in the positive interactions between the predominant genus Geobacter and other microorganisms as compared to the stage before FLO disturbance. Moreover, the keystone species in the networks after full recovery possessed more connections between Geobacter and potential synergistic species. Our results demonstrated that FLO, with broad-spectrum antibacterial ability, could restructure the EABs with more positive interactions for hydrogen production. This study demonstrated the response mechanisms of the MECs to the antibiotic disturbance, providing a scientific reference for the rapid development of this biotechnology to treat wastewater containing antibiotics.

  • Deterministic Assembly and Diversity Gradient Altered the Biofilm Community Performances of Bioreactors
    2019
    Co-Authors: Zhaojing Zhang, Kai Feng, Weiwei Cai, Huaqun Yin, Ye Deng, Daliang Ning
    Abstract:

    Community assembly process (determinism vs stochasticity) determines the composition and diversity of a microbial Community, and then shapes its functions. Understanding this complex process and its relationship to the Community functions becomes a very important task for the applications of microbial biotechnology. In this study, we applied microbial electrolysis cells (MECs) with moderate species numbers and easily tractable functions as a model ecosystem, and constructed a series of Biofilm communities with gradient biodiversity to examine the roles of Community assembly in determining microbial Community structure and functions. After stable Biofilms formed, the best MEC reactor performances (e.g., gas productivity, total energy efficiency) were achieved in the group in which Biofilms had the second highest α-diversity, and Biofilms with even lower diversity showed declining performance. Null model analyses indicated that both deterministic and stochastic assembly played roles in the formation of Biofilm communities. When deterministic assembly dominates this formation, the higher diversity of the Biofilm Community would generally show better reactor performance. However, when the stochasticity dominates the assembly process, the bioreactor performance would decline. This study provides novel evidence that the assembly mechanism could be one of the key processes to shift the functions, and proposes an important guidance for selecting the most efficient microorganisms for environmental biotechnologies

  • biodiversity and species competition regulate the resilience of microbial Biofilm Community
    Molecular Ecology, 2017
    Co-Authors: Kai Feng, Zhaojing Zhang, Weiwei Cai, Wenzong Liu, Huaqun Yin, Aijie Wang, Ye Deng
    Abstract:

    The relationship between biodiversity and ecosystem stability is poorly understood in microbial communities. Biofilm communities in small bioreactors called microbial electrolysis cells (MEC) contain moderate species numbers and easy tractable functional traits, thus providing an ideal platform for verifying ecological theories in microbial ecosystems. Here, we investigated the resilience of Biofilm communities with a gradient of diversity, and explored the relationship between biodiversity and stability in response to a pH shock. The results showed that all bioreactors could recover to stable performance after pH disturbance, exhibiting a great resilience ability. A further analysis of microbial composition showed that the rebound of Geobacter and other exoelectrogens contributed to the resilient effectiveness, and that the presence of Methanobrevibacter might delay the functional recovery of Biofilms. The microbial communities with higher diversity tended to be recovered faster, implying Biofilms with high biodiversity showed better resilience in response to environmental disturbance. Network analysis revealed that the negative interactions between the two dominant genera of Geobacter and Methanobrevibacter increased when the recovery time became longer, implying the internal resource or spatial competition of key functional taxa might fundamentally impact the resilience performances of Biofilm communities. This study provides new insights into our understanding of the relationship between diversity and ecosystem functioning.

Bruce E Rittmann - One of the best experts on this subject based on the ideXlab platform.

  • total electron acceptor loading and composition affect hexavalent uranium reduction and microbial Community structure in a membrane Biofilm reactor
    Water Research, 2017
    Co-Authors: Aura Ontiverosvalencia, Rosa Krajmalnikbrown, Chen Zhou, Zehra Esra Ilhan, Louis Cornette De Saint Cyr, Bruce E Rittmann
    Abstract:

    Molecular microbiology tools (i.e., 16S rDNA gene sequencing) were employed to elucidate changes in the microbial Community structure according to the total electron acceptor loading (controlled by influent flow rate and/or medium composition) in a H2-based membrane Biofilm reactor evaluated for removal of hexavalent uranium. Once nitrate, sulfate, and dissolved oxygen were replaced by U(VI) and bicarbonate and the total acceptor loading was lowered, slow-growing bacteria capable of reducing U(VI) to U(IV) dominated in the Biofilm Community: Replacing denitrifying bacteria Rhodocyclales and Burkholderiales were spore-producing Clostridiales and Natranaerobiales. Though potentially competing for electrons with U(VI) reducers, homo-acetogens helped attain steady U(VI) reduction, while methanogenesis inhibited U(VI) reduction. U(VI) reduction was reinstated through suppression of methanogenesis by addition of bromoethanesulfonate or by competition from SRB when sulfate was re-introduced. Predictive metagenome analysis further points out Community changes in response to alterations in the electron-acceptor loading: Sporulation and homo-acetogenesis were critical factors for strengthening stable microbial U(VI) reduction. This study documents that sporulation was important to long-term U(VI) reduction, whether or not microorganisms that carry out U(VI) reduction mediated by cytochrome c3, such as SRB and ferric-iron-reducers, were inhibited.

  • selecting anode respiring bacteria based on anode potential phylogenetic electrochemical and microscopic characterization
    Environmental Science & Technology, 2009
    Co-Authors: Cesar I Torres, Rosa Krajmalnikbrown, Prathap Parameswaran, Andrew K Marcus, Greg Wanger, Yuri A Gorby, Bruce E Rittmann
    Abstract:

    Anode-respiring bacteria (ARB) are able to transfer electrons contained in organic substrates to a solid electrode. The selection of ARB should depend on the anode potential, which determines the amount of energy available for bacterial growth and maintenance. In our study, we investigated how anode potential affected the microbial diversity of the Biofilm Community. We used a microbial electrolysis cell (MEC) containing four graphite electrodes, each at a different anode potential (Eanode = −0.15, −0.09, +0.02, and +0.37 V vs SHE). We used wastewater-activated sludge as inoculum, acetate as substrate, and continuous-flow operation. The two electrodes at the lowest potentials showed a faster Biofilm growth and produced the highest current densities, reaching up to 10.3 A/m2 at the saturation of an amperometric curve; the electrode at the highest potential produced a maximum of 0.6 A/m2. At low anode potentials, clone libraries showed a strong selection (92−99% of total clones) of an ARB that is 97% simila...

  • bioreduction of trichloroethene using a hydrogen based membrane Biofilm reactor
    Environmental Science & Technology, 2008
    Co-Authors: Rosa Krajmalnikbrown, Jin Wook Chung, Bruce E Rittmann
    Abstract:

    A H2-based, denitrifying membrane-Biofilm reactor (MBfR) was effective for removing trichloroethene (TCE) by reductive dechlorination. When TCE was first added to the MBfR, reductive dechlorination took place immediately and then increased over 18 weeks, and TCE was completely dechlorinated to ethene by about 120 days. These results indicate that TCE-dechlorinating bacteria were present naturally in the H2-based Biofilm, and that enrichment for TCE-dechlorinating bacteria occurred. Dehalococcoides were documented in the MBfR Biofilm before and after TCE feeding. Their proportion, quantified using the 16S rRNA gene, increased from 2.9 to 12% after TCE addition. This is the first report in which Dehalococcoides are proven to be present as part of an autotrophic Biofilm Community active in reductive dechlorination of TCE to ethene in a laboratory controlled experiment. Based on the complete reduction of TCE to ethene, the 16S rRNA clone libraries results, and the amount of tceA and bvcA, it appears that at l...

  • bioreduction of trichloroethene using a hydrogen based membrane Biofilm reactor
    Environmental Science & Technology, 2008
    Co-Authors: Jin Wook Chung, Rosa Krajmalnikbrown, Bruce E Rittmann
    Abstract:

    A H2-based, denitrifying membrane-Biofilm reactor (MBfR) was effective for removing trichloroethene (TCE) by reductive dechlorination. When TCE was first added to the MBfR, reductive dechlorination took place immediately and then increased over 18 weeks, and TCE was completely dechlorinated to ethene by about 120 days. These results indicate that TCE-dechlorinating bacteria were present naturally in the H2-based Biofilm, and that enrichment for TCE-dechlorinating bacteria occurred. Dehalococcoides were documented in the MBfR Biofilm before and after TCE feeding. Their proportion, quantified using the 16S rRNA gene, increased from 2.9 to 12% after TCE addition. This is the first report in which Dehalococcoides are proven to be present as part of an autotrophic Biofilm Community active in reductive dechlorination of TCE to ethene in a laboratory controlled experiment. Based on the complete reduction of TCE to ethene, the 16S rRNA clone libraries results, and the amount of tceA and bvcA, it appears that at least two Dehalococcoides strains were present in the enriched Biofilm. One of them seems to be a new strain that is unique for having tceA and bvcA reductive dehalogenases.

Jianghan Luo - One of the best experts on this subject based on the ideXlab platform.

  • microbial Community structures in a closed raw water distribution system Biofilm as revealed by 454 pyrosequencing analysis and the effect of microbial Biofilm communities on raw water quality
    Bioresource Technology, 2013
    Co-Authors: Jianghan Luo, Heng Liang, Lijun Yan, Yanling Yang
    Abstract:

    This is the first report on the characterization of the microbial Biofilm Community structure and water quality change along a closed and stable raw water distribution system. 454-pyrosequencing was employed to investigate the microbial communities in four Biofilm samples. 25,426 optimized sequences were obtained. Results showed Proteobacteria was the dominant phylum in each Biofilm sample. The abundance of Nitrospiraes in M6 Biofilm, Firmicutes in M8 Biofilm, Actinobacteria in M9 Biofilm were higher by comparing with other three Biofilm samples. The M6 microbial Biofilm Community structure was similar to that of M7, dissimilar to that of M9. Dissolved oxygen and nitrogen was probably major factors to influence the microbial Biofilm communities. Nitrospiraes in M6 Biofilm and Firmicutes in M8 Biofilm were crucial to remove ammonia nitrogen and nitrate in raw water. How to enrich functional microbes in Biofilm to pretreat raw water is an important area of future research.

Lutgarde Raskin - One of the best experts on this subject based on the ideXlab platform.

  • Biofilms in full scale drinking water ozone contactors contribute viable bacteria to ozonated water
    Environmental Science & Technology, 2018
    Co-Authors: Nadine Kotlarz, Nicole Rockey, Terese M. Olson, Sarah-jane Haig, Larry Sanford, John J. Lipuma, Lutgarde Raskin
    Abstract:

    Concentrations of viable microbial cells were monitored using culture-based and culture-independent methods across multichamber ozone contactors in a full-scale drinking water treatment plant. Membrane-intact and culturable cell concentrations in ozone contactor effluents ranged from 1200 to 3750 cells/mL and from 200 to 3850 colony forming units/mL, respectively. Viable cell concentrations decreased significantly in the first ozone contact chamber, but rose, even as ozone exposure increased, in subsequent chambers. Our results implicate microbial detachment from Biofilms on contactor surfaces, and from biomass present within lime softening sediments in a hydraulic dead zone, as a possible reason for increasing cell concentrations in water samples from sequential ozone chambers. Biofilm Community structures on baffle walls upstream and downstream from the dead zone were significantly different from each other (p = 0.017). The Biofilms downstream of the dead zone contained a significantly (p = 0.036) highe...

  • Biofilms in Full-Scale Drinking Water Ozone Contactors Contribute Viable Bacteria to Ozonated Water
    2018
    Co-Authors: Nadine Kotlarz, Nicole Rockey, Terese M. Olson, Sarah-jane Haig, Larry Sanford, John J. Lipuma, Lutgarde Raskin
    Abstract:

    Concentrations of viable microbial cells were monitored using culture-based and culture-independent methods across multichamber ozone contactors in a full-scale drinking water treatment plant. Membrane-intact and culturable cell concentrations in ozone contactor effluents ranged from 1200 to 3750 cells/mL and from 200 to 3850 colony forming units/mL, respectively. Viable cell concentrations decreased significantly in the first ozone contact chamber, but rose, even as ozone exposure increased, in subsequent chambers. Our results implicate microbial detachment from Biofilms on contactor surfaces, and from biomass present within lime softening sediments in a hydraulic dead zone, as a possible reason for increasing cell concentrations in water samples from sequential ozone chambers. Biofilm Community structures on baffle walls upstream and downstream from the dead zone were significantly different from each other (p = 0.017). The Biofilms downstream of the dead zone contained a significantly (p = 0.036) higher relative abundance of bacteria of the genera Mycobacterium and Legionella than the upstream Biofilms. These results have important implications as the effluent from ozone contactors is often treated further in biologically active filters and bacteria in ozonated water continuously seed filter microbial communities

  • impact of microfiltration treatment of secondary wastewater effluent on biofouling of reverse osmosis membranes
    Water Research, 2010
    Co-Authors: Moshe Herzberg, David Berry, Lutgarde Raskin
    Abstract:

    Abstract The effects of microfiltration (MF) as pretreatment for reverse osmosis (RO) on biofouling of RO membranes were analyzed with secondary wastewater effluents. MF pretreatment reduced permeate flux decline two- to three-fold, while increasing salt rejection. Additionally, the oxygen uptake rate (OUR) in the biofouling layer of the RO membrane was higher for an RO system that received pretreated secondary wastewater effluent compared to a control RO system that received untreated secondary effluent, likely due to the removal of inert particulate/colloidal matter during MF. A higher cell viability in the RO Biofilm was observed close to the membrane surface irrespective of pretreatment, which is consistent with the Biofilm-enhanced concentration polarization effect. Bacterial 16S rRNA gene clone library analysis revealed dominant Biofilm communities of Proteobacteria and Bacteroidetes under all conditions. The Cramer–von Mises test statistic showed that MF pretreatment did not significantly change the bacterial Community structure of RO membrane Biofilms, though it affected bacterial Community structure of non-membrane-associated Biofilms (collected from the feed tank wall). The finding that the Biofilm Community developed on the RO membrane was not influenced by MF pretreatment may imply that RO membranes select for a conserved Biofilm Community.