15 results for Lewis, Gillian, Conference poster

  • Metabolomics as a novel approach to study mixed species biofilms of stream bacteria exhibiting mutualistic and antagonistic responses

    Washington, Vidya; Villas-Boas, Silas; Lewis, Gillian (2008-08-17)

    Conference poster
    The University of Auckland Library

    Experimental objective / Purpose 1. To investigate the metabolic interactions of bacterial species using metabolic footprint profiling. 2. As proof of concept, microbes exhibiting mutualistic and antagonistic associations were chosen for this study.

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  • Effects of Storm water metal contaminats on microbial communities in stream biofilm revealed by Automated Ribosomal Intergenic Spacer Analysis (ARISA)

    Ancion, Pierre; Lear, Gavin; Lewis, Gillian (2008-08-17)

    Conference poster
    The University of Auckland Library

    Stormwater metal contaminants are known to be a threat to our freshwater environments but little is known about their effects on stream micro-organisms. This project investigates accumulation and release of the most common stormwater metal contaminants (zinc, copper and lead) in stream biofilms and their effects on bacterial populations.

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  • What drives bacterial community structure in stream biofilms?

    Roberts, Kelly; Lear, Gavin; Turner, Susan; Lewis, Gillian (2008-08-17)

    Conference poster
    The University of Auckland Library

    BACKGROUND The microorganisms within biofilms are the key basal trophic level within most freshwater systems. However, microbial structure, function and succession in natural stream systems remain poorly understood. This research characterises the biofilm community structure of stream biofilms experiencing different anthropogenic impacts and how they change over time. Our aim is describe the changes in bacterial biofilm communities over time and to investigate what drives these changes.

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  • Stream Restoration: Getting the microbial ecology right.

    Lewis, Gillian; Lear, Gavin; Turner, Susan; Boothroyd, Ian; Stott, Rebecca; Roberts, Kelly; Ancion, Pierre; Dopheide, Andrew; Washington, Vidya; Knight, Duane; Smith, Joanna (2008-08-17)

    Conference poster
    The University of Auckland Library

    A comprehensive program to re-establish the structure and function of an ecosystem, including its natural diversity and aquatic habitats.

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  • Bacterially mediated manganese deposition in novel "anelli" within the biofilms of an impacted urban stream

    Smith, JP; Lewis, Gillian (2007-12-02)

    Conference poster
    The University of Auckland Library

    The purpose of this work is to identify bacteria responsible for the formation of manganese containing anelli within stream biofilms, and study their distribution. Manganese oxidising bacteria are part of a diverse group of organisms found commonly within many disparate environments, which deposit manganese and iron biominerals within biofilms and flocs [1]. The purpose of microbial manganese oxidation is poorly understood, but may be associated with energy production, mobilisation of nutrients, protection and/or detoxification [1, 2]. Manganese has a high sorptive capacity for heavy metals, metalloids, and other ions, as well as a strong oxidizing potential, and therefore frequently induces co-precipitation of cations present within the surrounding environment [1]. Within urban streams contaminants such as heavy metals may therefore potentially be concentrated within steam biofilms in the presence of manganese oxidising bacteria.

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  • Molecular investigation of protozoan diversity in stream biofilms

    Dopheide, AJ; Lear, Gavin; Lewis, Gillian (2006-11-21)

    Conference poster
    The University of Auckland Library

    This research aims to test the following hypothesis: that molecular biological methods will allow description of protozoan diversity and ecology in streams.

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  • The use of whole community bacterial indicators to monitor ecological health, function and variability within stream biofilms

    Lear, Gavin; Boothroyd, IK; Lewis, Gillian (2009-08-30)

    Conference poster
    The University of Auckland Library

    This study describes the extent of variability in biofilm bacterial community structure across a broad range of spatial and temporal scales and assesses whether this may be used as an indicator of stream ecological health and function. A community DNA fingerprinting technique (Automated Ribosomal Intergenic Spacer Analysis - ARISA) was used to examine the structure of bacterial communities within freshwater stream biofilms. When compared with macrobenthic invertebrate community assemblages using multi-dimensional scaling techniques, similar broad-scale trends in population structure were revealed between organisms at these different trophic levels. For both communities, spatial variability in community structure was greater between streams than within each site, or compared to temporal variability measured over 1 year. Distance-based redundancy analysis of both bacterial ARISA and macroinvertebrate data estimated that the largest cause of variation in community structure was due to differences in catchment land-use, rather than any single water quality parameter (e.g. ph or ammoniacal nitrogen). Multidimensional scaling of ARISA data also revealed significant differences in community structure between urban, and less impacted stream sites, providing evidence that whole-bacterial communities could be used as an indicator of freshwater ecological health, analogous to the way that macroinvertebrate communities have been used for many years. In conclusion, we propose the analysis of whole bacterial communities as a cost-effective, high throughput alternative indicator of freshwater ecological health.

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  • Ciliate Diversity in Stream Biofilms revealed by group-specific PCR primers.

    Dopheide, Andrew; Lear, Gavin; Stott, R; Lewis, Gillian (2008-08-17)

    Conference poster
    The University of Auckland Library

    The ciliates are a diverse protozoan phylum, thought to be of considerable ecological importance in stream ecosystems, including organisms which are abundant and important consumers of bacteria, algae and other protozoa. Understanding of ciliate diversity and ecology is limited, however, particularly in benthic habitats such as stream biofilms. In this study, phylum-specific PCR primers were used in combination with cloning, sequencing and terminal restriction fragment length polymorphism (T-RFLP) analysis to investigate ciliate communities in stream biofilms.

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  • Human Adenovirus ecology in environmental waters in New Zealand

    Dong, Yimin; Lewis, Gillian (2008-08-17)

    Conference poster
    The University of Auckland Library

    A major New Zealand study of pathogen occurrence in surface freshwaters identified occurrence of human adenovirus in 30% of sites and samples by qualitative PCR based methods. The source or nature of these viruses was not clear from the study and raises important questions in both viral ecology and human health protection. The aim of this study was to begin to unravel these questions by (i) development of specific quantitative analysis methods for adenoviruses in water and (ii) to target identifiable groups of adenovirus associated with human respiratory or gastrointestinal infections. These quantitative group specific real time PCR methods were tested in drinking water, recreational water, river water and wastewater. Adenovirus was detected in all primary wastewater samples tested (n=10) at high genome copy number (1.87 x104 to 4.6 x106 per litre) and in 33% (n=15) of the river water and 11% (n=27) of the treated drinking water samples. In addition, adenovirus was detected in 5 of the 6 estuarine recreational water samples (17 to 1190 virus genome copies per litre). DNA sequence analysis suggested that human adenovirus group C (respiratory infection associated) were most commonly associated with river, recreational and drinking water. Group F adenovirus (gastroenteritis associated viruses) were found to dominate in most wastewater (5 - 100 % total adenovirus) but were not detected in surface waters. This study suggests that the ecology of specific groups or types of adenovirus is sufficiently different, external to the host, to have important implications for human health risk assessment.

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  • Effect of light regimes on the utilisation of an exogenous carbon source by freshwater biofilm communities

    Lear, Gavin; Lewis, Gillian (2007-06-23)

    Conference poster
    The University of Auckland Library

    Biofilms are a major source of ‘in stream’ primary production, exhibiting high population density, and being an important source of carbon for microbial heterotrophs. Changing patterns of land-use within freshwater catchment areas may greatly impact on stream biofilm microbial community structure, which in turn may influence the speed and extent with which full ecosystem recovery may occur. This study reports how freshwater biofilm communities respond to additions of acetate, used as a proxy for organic matter, the primary source of carbon within shaded forests and headwater streams. The use of [ 13C] acetate and subsequent isolation of 13C-labelled nucleic acids from the metabolically active fraction of the bacterial community enabled substrate assimilating organisms to be identified. In addition, biofilms were exposed to varied levels of incident light to assess the relative contribution of phototrophic and heterotrophic nutrition.

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  • Use of whole-community bacterial indicators to monitor ecological health, function and variability within freshwater stream biofilms.

    Lear, Gavin; Smith, Joanna; Roberts, Kelly; Boothroyd, Ian; Lewis, Gillian (2008-08-17)

    Conference poster
    The University of Auckland Library

    This study describes the extent of variability in biofilm bacterial community structure across a broad range of spatial and temporal scales and assesses whether this may be used as an indicator of stream ecological health and function. A community DNA fingerprinting technique (Automated Ribosomal Intergenic Spacer Analysis - ARISA) was used to examine the structure of bacterial communities within freshwater stream biofilms. When compared with macrobenthic invertebrate community assemblages using multi-dimensional scaling techniques, similar broad-scale trends in population structure were revealed between organisms at these different trophic levels. For both communities, spatial variability in community structure was greater between streams than within each site, or compared to temporal variability measured over 1 year. Distance-based redundancy analysis of both bacterial ARISA and macroinvertebrate data estimated that the largest cause of variation in community structure was due to differences in catchment land-use, rather than any single water quality parameter (e.g. ph or ammoniacal nitrogen). Multidimensional scaling of ARISA data also revealed significant differences in community structure between urban, and less impacted stream sites, providing evidence that whole-bacterial communities could be used as an indicator of freshwater ecological health, analogous to the way that macroinvertebrate communities have been used for many years. In conclusion, we propose the analysis of whole bacterial communities as a cost-effective, high throughput alternative indicator of freshwater ecological health.

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  • Using stream biofilm microbial communities as indicators of freshwater ecosystem health

    Lewis, Gillian; Ancion, PY; Lear, G; Roberts, K; Washington, V (2010-08-23)

    Conference poster
    The University of Auckland Library

    Stream biofilms are a complex aggregation of microorganisms embedded in a polymer matrix and cover almost every surface in freshwater environments. Because of their sedentary way of life, microorganisms associated with biofilms are affected by past and present environmental conditions and therefore constitute a potential integrative indicator of stream health. A wide range of experiments was conducted in both flow chamber microcosms and natural stream environments to investigate the main drivers of microbial community structure and composition and evaluate the potential use of biofilms as a bio-indicator of freshwater ecosystem health. Using community fingerprinting techniques such as terminal-Restriction Fragment Length Polymorphism and Automated Ribosomal Intergenic Spacer Analysis as well as 16S rRNA gene clone libraries we investigated variations occurring in biofilm bacterial and ciliate protozoan communities. Initial experiments conducted in flow chamber microcosms showed that significant differences in microbial community structure could be detected within only a few days of exposure to common water contaminants and remained detectable weeks after transfer to uncontaminated water. Further research investigating biofilm of more than 60 stream sites variously impacted by urbanization revealed a strong separation between rural and urban streams and confirmed the potential use of stream biofilm as a bio-indicator of stream health. Environmental monitoring techniques developed in this project were then successfully tested to investigate the efficacy of an enclosed stormwater treatment system, where traditional biological indicators such as macro-benthic invertebrates were not available. We are now extending our research to 300 different streams in order to define a general Bacterial Community Index characterising stream ecosystem health based on the structure of biofilm bacterial communities.

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  • Unusual Bacterially mediated manganese-based structures within biofilms from urban streams.

    Smith, Joanna; Lewis, Gillian (2008-08-17)

    Conference poster
    The University of Auckland Library

    The objectives of this study were to describe the occurrence and nature of unusual brown “doughnut”-shaped microbial structures present within the biofilms of several urban streams in Auckland, New Zealand, and the bacteria responsible for their formation. These structures, termed anelli, were observed with light and scanning electron microscopy to be shallow conical microcolonies consisting of a ring, enriched in manganese and iron, surrounding a central pore. Bacteria were observed to reside within the pores, although anelli seen within biofilms were frequently vacant structures. A manganese depositing, anellus-forming bacterium (JOSHI_001) was isolated on solid media, and analysis of 16S rRNA gene sequences revealed this bacterium to belong to the order Burkholderiales within the class β-proteobacteria, closely related to the manganese-depositing genus Leptothrix. The presence of anelli within biofilms was found to require Mn(II), however, elevated levels of this element within stream water did not necessarily result in growth of anelli. Anelli were only dominant structures within biofilms from those stream sites subjected to a high level of anthropogenic impact, suggesting that Mn(II) may not be the only factor influencing competitive capability. Investigation of additional streams within the Auckland region, influenced by a range of different types of anthropogenic impact is ongoing. Molecular analysis indicated that although anelli were structurally dominant, the β-proteobacteria comprised only a minor component of the bacterial community present within the biofilms. JOSHI_001 may have a significant impact on geochemical cycling and stream ecology within streams subjected to high levels of anthropogenic impact.

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  • Human Activities Modify Bacterial Diversity in Stream Benthic Biofilm Communities

    Lewis, Gillian; Roberts, Kelly; Turner, Susan; Lear, Gavin (2008-06-01)

    Conference poster
    The University of Auckland Library

    This study tests the hypothesis that human impact is an important driver of stream biofilm bacterial population diversity. The seasonal bacterial composition of biofilm in 4 streams with different levels of human impact was determined over 2 years. Bacterial diversity derived from 16S rDNA clone libraries, shows both between stream differences and seasonal transitions in bacterial occurrence and population dominance at a class and genus level. Diversity analysis calculated on pooled seasonal data (class level identification) shows that while composition of the populations are different there is a similar level of both bacterial richness and bacterial diversity in each stream. Trends in bacterial occurrence suggest that the most degraded stream were dominated by cyanobacteria, the mid range impact streams by aeromonads and gamma proteobacteria, while the unimpacted stream showed both high diversity and no dominance by any particular class.

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  • Ecosystem responses to multiple-stressor gradients: Nutrient and sediment addition to experimental stream channels

    Wagenhoff, A; Matthaei, CD; Lear, Gavin; Lewis, Gillian; Townsend, CR (2009-05-16)

    Conference poster
    The University of Auckland Library

    Agricultural land use can strongly affect stream ecosystems by increasing levels of nutrients and fine sediment cover on the streambed. Knowledge of patterns in ecological responses along gradients of these two stressors will help define thresholds of harm. Leaf breakdown rates, algal and bacterial communities are directly and/or indirectly influenced by nutrient supply and fine sediment cover. To investigate the effects of stressor gradients and their interactions on these biological response parameters, we designed a full-factorial experiment in circular stream-side channels with eight levels each of nutrients (36 to 6900 μg·l-1 DIN, 1.4 to 450 μg·l-1 DRP) and fine sediment (0 to 100 % cover). Algal biomass, bacterial diversity and leaf pack decomposition were determined after three weeks of exposure to both stressors. Algal biomass was significantly higher in channels with lower levels of fine sediment. Bacterial diversity generally increased with increasing nutrient concentrations up to an intermediate nutrient level but then decreased again with the exception of reaching the highest diversity overall at the top nutrient level. Thus, increased levels of nutrients and fine sediment caused major changes to the algal and bacterial communities. In turn, these changes affect other food-web components as well as ecosystem functioning, including decomposition.

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