NobleBlocks

Melbourne Water

governmentMelbourne, Victoria, Australia

Research output, citation impact, and the most-cited recent papers from Melbourne Water (Australia). Aggregated across the NobleBlocks index of 300M+ scholarly works.

Total works
870
Citations
51.5K
h-index
100
i10-index
723
Also known as
Melbourne Water

Top-cited papers from Melbourne Water

A communal catalogue reveals Earth’s multiscale microbial diversity
Luke Thompson, Jon G. Sanders, Daniel McDonald, Amnon Amir +4 more
2017· Nature2.9Kdoi:10.1038/nature24621

Our growing awareness of the microbial world's importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of diversity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earth's microbial diversity.

Global monitoring of antimicrobial resistance based on metagenomics analyses of urban sewage
René S. Hendriksen, Patrick Munk, Patrick Murigu Kamau Njage, Bram van Bunnik +4 more
2019· Nature Communications1.1Kdoi:10.1038/s41467-019-08853-3

Antimicrobial resistance (AMR) is a serious threat to global public health, but obtaining representative data on AMR for healthy human populations is difficult. Here, we use metagenomic analysis of untreated sewage to characterize the bacterial resistome from 79 sites in 60 countries. We find systematic differences in abundance and diversity of AMR genes between Europe/North-America/Oceania and Africa/Asia/South-America. Antimicrobial use data and bacterial taxonomy only explains a minor part of the AMR variation that we observe. We find no evidence for cross-selection between antimicrobial classes, or for effect of air travel between sites. However, AMR gene abundance strongly correlates with socio-economic, health and environmental factors, which we use to predict AMR gene abundances in all countries in the world. Our findings suggest that global AMR gene diversity and abundance vary by region, and that improving sanitation and health could potentially limit the global burden of AMR. We propose metagenomic analysis of sewage as an ethically acceptable and economically feasible approach for continuous global surveillance and prediction of AMR.

A review of analytical techniques for quantifying microplastics in sediments
Joanne S. Hanvey, Phoebe Lewis, Jennifer L. Lavers, Nicholas D. Crosbie +2 more
2016· Analytical Methods468doi:10.1039/c6ay02707e

In this review the analytical techniques for measuring microplastics in sediment have been evaluated.

Alternative Methods for Measuring Inorganic, Organic, and Total Dissolved Nitrogen in Soil
Rebecca Hood‐Nowotny, Nina Hinko‐Najera, Erich Inselbacher, Petra Lachouani +1 more
2010· Soil Science Society of America Journal431doi:10.2136/sssaj2009.0389

There are numerous methods for measuring inorganic, dissolved organic, and microbial N in soils, although many of these are complex or require expensive equipment. We have modified methods for the measurement of NH 4 + , NO 3 − , total dissolved N (TDN), and soil microbial biomass N (SMBN) in soils. The methods are based on a microtiter plate format and are rapid and simple to perform. Ammonium is quantified by a colorimetric method based on the Berthelot reaction. Total dissolved N and SMBN (by CH 3 Cl fumigation‐extraction) are quantified as NO 3 − after alkaline persulfate oxidation. Nitrate is estimated directly or after persulfate oxidation by reduction of NO 3 − to NO 2 − by VCl 3 and subsequent colorimetric determination of NO 2 − by acidic Griess reaction. The new suite of methods was compared with conventional methods such as high‐performance anion‐exchange chromatography for NO 3 − and high‐temperature catalytic oxidation for TDN. Our methods produced comparable detection limits, linearities, and precisions compared with the conventional methods. Limits of quantification were 7 μg NH 4 + –N L −1 , 55 μg NO 3 − –N L −1 , and 0.275 mg TDN L −1 The accuracy of the proposed methods was excellent, with recoveries of added NH 4 + , NO 3 − , and glycine ranging between 96 and 99%. Linearities of the respective calibrations were high ( R 2 > 0.99), and precisions for NH 4 + (CV = 2.1%), NO 3 − (CV = 3.5%), and TDN (CV = 3.9%) were comparable to the reference methods. The simplicity, rapidity, and low cost of the proposed methods therefore allow an expansion of the scope and range of N cycle studies where sophisticated instrumentation is not available.

Robert Barnes and His Obstetric Forceps
Frank Förster
1971· Australian and New Zealand Journal of Obstetrics and Gynaecology382doi:10.1111/j.1479-828x.1971.tb00468.x

Summary Robert Barnes’ (1817‐1907) position in British obstetrics and gynaecology and his association with Australia are surveyed. The introduction of his obstetrical forceps into this country is traced. The reasons for the common, widespread use of this century‐old instrument are given. Strong criticism is made of the suitability of this design for modern clinical practice. A study made of 15 different makes of Barnes’ forceps used in Melbourne labour‐wards showed great variation in their measurements. It was concluded that (1) Barnes’ forceps should be relegated to the museum (2) a forceps designed for the type of delivery now being undertaken is required and (3) there should be standards for the manufacture of forceps.

Relationships between stem diameter, sapwood area, leaf area and transpiration in a young mountain ash forest
Rob Vertessy, Richard G. Benyon, Sharon O'Sullivan, P. R. Gribben
1995· Tree Physiology364doi:10.1093/treephys/15.9.559

We examined relationships between stem diameter, sapwood area, leaf area and transpiration in a 15-year-old mountain ash (Eucalyptus regnans F. Muell.) forest containing silver wattle (Acacia dealbata Link.) as a suppressed overstory species and mountain hickory (Acacia frigescens J.H. Willis) as an understory species. Stem diameter explained 93% of the variation in leaf area, 96% of the variation in sapwood area and 88% of the variation in mean daily spring transpiration in 19 mountain ash trees. In seven silver wattle trees, stem diameter explained 87% of the variation in sapwood area but was a poor predictor of the other variables. When transpiration measurements from individual trees were scaled up to a plot basis, using stem diameter values for 164 mountain ash trees and 124 silver wattle trees, mean daily spring transpiration rates of the two species were 2.3 and 0.6 mm day(-1), respectively. The leaf area index of the plot was estimated directly by destructive sampling, and indirectly with an LAI-2000 plant canopy analyzer and by hemispherical canopy photography. All three methods gave similar results.

Key factors influencing differences in stream water quality across space
Anna Lintern, J. Angus Webb, Dongryeol Ryu, Shuci Liu +4 more
2017· Wiley Interdisciplinary Reviews Water351doi:10.1002/wat2.1260

Globally, many rivers are experiencing declining water quality, for example, with altered levels of sediments, salts, and nutrients. Effective water quality management requires a sound understanding of how and why water quality differs across space, both within and between river catchments. Land cover, land use, land management, atmospheric deposition, geology and soil type, climate, topography, and catchment hydrology are the key features of a catchment that affect: (1) the amount of suspended sediment, nutrient, and salt concentrations in catchments (i.e., the source), (2) the mobilization ,and (3) the delivery of these constituents to receiving waters. There are, however, complexities in the relationship between landscape characteristics and stream water quality. The strength of this relationship can be influenced by the distance and spatial arrangement of constituent sources within the catchment, cross correlations between landscape characteristics, and seasonality. A knowledge gap that should be addressed in future studies is that of interactions and cross correlations between landscape characteristics. There is currently limited understanding of how the relationships between landscape characteristics and water quality responses can shift based on the other characteristics of the catchment. Understanding the many forces driving stream water quality and the complexities and interactions in these forces is necessary for the development of successful water quality management strategies. This knowledge could be used to develop predictive models, which would aid in forecasting of riverine water quality. WIREs Water 2018, 5:e1260. doi: 10.1002/wat2.1260 This article is categorized under: Science of Water > Hydrological Processes Science of Water > Water Quality

Social media and suicide prevention: a systematic review
Jo Robinson, Georgina Cox, Eleanor Bailey, Sarah Hetrick +3 more
2015· Early Intervention in Psychiatry342doi:10.1111/eip.12229

AIM: Social media platforms are commonly used for the expression of suicidal thoughts and feelings, particularly by young people. Despite this, little is known about the ways in which social media can be used for suicide prevention. The aim of this study was to conduct a systematic review to identify current evidence pertaining to the ways in which social media are currently used as a tool for suicide prevention. METHODS: Medline, PsycInfo, Embase, CINHAL and the Cochrane Library were searched for articles published between 1991 and April 2014. English language articles with a focus on suicide-related behaviour and social media were included. No exclusion was placed on study design. RESULTS: Thirty studies were included; 4 described the development of social media sites designed for suicide prevention, 6 examined the potential of social media in terms of its ability to reach or identify people at risk of suicide, 15 examined the ways in which people used social media for suicide prevention-related purposes, and 5 examined the experiences of people who had used social media sites for suicide prevention purposes. No intervention studies were identified. CONCLUSION: Social media platforms can reach large numbers of otherwise hard-to-engage individuals, may allow others to intervene following an expression of suicidal ideation online, and provide an anonymous, accessible and non-judgmental forum for sharing experiences. Challenges include difficulties controlling user behaviour and accurately assessing risk, issues relating to privacy and confidentiality and the possibility of contagion. Social media appears to hold significant potential for suicide prevention; however, additional research into its safety and efficacy is required.

An investigation into per- and polyfluoroalkyl substances (PFAS) in nineteen Australian wastewater treatment plants (WWTPs)
Timothy L. Coggan, Damien Moodie, Adam Kolobaric, Drew Szabo +4 more
2019· Heliyon308doi:10.1016/j.heliyon.2019.e02316

dw) in WWTP solids. Similar to WWTPs worldwide, perfluorocarboxylic acids were generally higher in effluent, compared to influent. Partitioning to solids within WWTPs increased with increasing fluoroalkyl chain length from 0.05 to 1.22 log units. Many PFAS were highly correlated, and PCA analysis showed strong associations between two groups: odd chained PFCAs, PFHxA and PFSAs; and 6:2 FTS with daily inflow volume and the proportion of trade waste accepted by WWTPs (as % of typical dry inflow). The compounds PFPeA, PFHxA, PFHpA, PFOA, PFNA, and PFDA increased significantly between influent and final effluent. The compounds 6:2 FTS and 8:2 FTS were quantified and F-53B detected and reported in Australian WWTP matrices. The compound 6:2 FTS was an important contributor to PFAS emissions in the studied Australian WWTPs, supporting the need for future research on its sources (including precursor degradation), environmental fate and impact in Australian aquatic environments receiving WWTP effluent.

Genomic analysis of sewage from 101 countries reveals global landscape of antimicrobial resistance
Patrick Munk, Christian Brinch, Frederik Duus Møller, Thomas Nordahl Petersen +4 more
2022· Nature Communications269doi:10.1038/s41467-022-34312-7

Antimicrobial resistance (AMR) is a major threat to global health. Understanding the emergence, evolution, and transmission of individual antibiotic resistance genes (ARGs) is essential to develop sustainable strategies combatting this threat. Here, we use metagenomic sequencing to analyse ARGs in 757 sewage samples from 243 cities in 101 countries, collected from 2016 to 2019. We find regional patterns in resistomes, and these differ between subsets corresponding to drug classes and are partly driven by taxonomic variation. The genetic environments of 49 common ARGs are highly diverse, with most common ARGs carried by multiple distinct genomic contexts globally and sometimes on plasmids. Analysis of flanking sequence revealed ARG-specific patterns of dispersal limitation and global transmission. Our data furthermore suggest certain geographies are more prone to transmission events and should receive additional attention.

A global database of lake surface temperatures collected by in situ and satellite methods from 1985–2009
Sapna Sharma, Derek K. Gray, Jordan S. Read, Catherine M. O’Reilly +4 more
2015· Scientific Data237doi:10.1038/sdata.2015.8

Global environmental change has influenced lake surface temperatures, a key driver of ecosystem structure and function. Recent studies have suggested significant warming of water temperatures in individual lakes across many different regions around the world. However, the spatial and temporal coherence associated with the magnitude of these trends remains unclear. Thus, a global data set of water temperature is required to understand and synthesize global, long-term trends in surface water temperatures of inland bodies of water. We assembled a database of summer lake surface temperatures for 291 lakes collected in situ and/or by satellites for the period 1985-2009. In addition, corresponding climatic drivers (air temperatures, solar radiation, and cloud cover) and geomorphometric characteristics (latitude, longitude, elevation, lake surface area, maximum depth, mean depth, and volume) that influence lake surface temperatures were compiled for each lake. This unique dataset offers an invaluable baseline perspective on global-scale lake thermal conditions as environmental change continues.

Internal conductance does not scale with photosynthetic capacity: implications for carbon isotope discrimination and the economics of water and nitrogen use in photosynthesis
Charles R. Warren, Mark A. Adams
2005· Plant Cell & Environment232doi:10.1111/j.1365-3040.2005.01412.x

Central paradigms of ecophysiology are that there are recognizable and even explicit and predictable patterns among species, genera, and life forms in the economics of water and nitrogen use in photosynthesis and in carbon isotope discrimination (delta). However most previous examinations have implicitly assumed an infinite internal conductance (gi) and/or that internal conductance scales with the biochemical capacity for photosynthesis. Examination of published data for 54 species and a detailed examination for three well-characterized species--Eucalyptus globulus, Pseudotsuga menziesii and Phaseolus vulgaris--show these assumptions to be incorrect. The reduction in concentration of CO2 between the substomatal cavity (Ci) and the site of carbon fixation (Cc) varies greatly among species. Photosynthesis does not scale perfectly with gi and there is a general trend for plants with low gi to have a larger draw-down from Ci to Cc, further confounding efforts to scale photosynthesis and other attributes with gi. Variation in the gi-photosynthesis relationship contributes to variation in photosynthetic 'use' efficiency of N (PNUE) and water (WUE). Delta is an information-rich signal, but for many species only about two-thirds of this information relates to A/gs with the remaining one-third related to A/gi. Using data for three well-studied species we demonstrate that at common WUE, delta may vary by up to 3 per thousand. This is as large or larger than is commonly reported in many interspecific comparisons of delta, and adds to previous warnings about simplistic interpretations of WUE based on delta. A priority for future research should be elucidation of relationships between gi and gs and how these vary in response to environmental conditions (e.g. soil water, leaf-to-air vapour pressure deficit, temperature) and among species.

Severe consequences of habitat fragmentation on genetic diversity of an endangered Australian freshwater fish: A call for assisted gene flow
Alexandra Pavlova, Luciano B. Beheregaray, Rhys A. Coleman, Dean M. Gilligan +4 more
2017· Evolutionary Applications230doi:10.1111/eva.12484

Abstract Genetic diversity underpins the ability of populations to persist and adapt to environmental changes. Substantial empirical data show that genetic diversity rapidly deteriorates in small and isolated populations due to genetic drift, leading to reduction in adaptive potential and fitness and increase in inbreeding. Assisted gene flow (e.g. via translocations) can reverse these trends, but lack of data on fitness loss and fear of impairing population “uniqueness” often prevents managers from acting. Here, we use population genetic and riverscape genetic analyses and simulations to explore the consequences of extensive habitat loss and fragmentation on population genetic diversity and future population trajectories of an endangered Australian freshwater fish, Macquarie perch Macquaria australasica . Using guidelines to assess the risk of outbreeding depression under admixture, we develop recommendations for population management, identify populations requiring genetic rescue and/or genetic restoration and potential donor sources. We found that most remaining populations of Macquarie perch have low genetic diversity, and effective population sizes below the threshold required to retain adaptive potential. Our simulations showed that under management inaction, smaller populations of Macquarie perch will face inbreeding depression within a few decades, but regular small‐scale translocations will rapidly rescue populations from inbreeding depression and increase adaptive potential through genetic restoration. Despite the lack of data on fitness loss, based on our genetic data for Macquarie perch populations, simulations and empirical results from other systems, we recommend regular and frequent translocations among remnant populations within catchments. These translocations will emulate the effect of historical gene flow and improve population persistence through decrease in demographic and genetic stochasticity. Increasing population genetic connectivity within each catchment will help to maintain large effective population sizes and maximize species adaptive potential. The approach proposed here could be readily applicable to genetic management of other threatened species to improve their adaptive potential.

Seagrass Restoration Is Possible: Insights and Lessons From Australia and New Zealand
Yi Mei Tan, Oliver Dalby, Gary A. Kendrick, John Statton +4 more
2020· Frontiers in Marine Science195doi:10.3389/fmars.2020.00617

Seagrasses are important marine ecosystems situated throughout the world’s coastlines. They are facing declines around the world due to global and local threats such as rising ocean temperatures, coastal development and pollution from sewage outfalls and agriculture. Efforts have been made to reduce seagrass loss through reducing local and regional stressors, and through active restoration. Seagrass restoration is rapidly maturing but improved restoration practices are needed to enhance the success of future programs. Major gaps in knowledge remain, especially our understanding of how to restore tropical species in Australia. Prior research efforts have provided valuable insights into factors influencing the outcomes of restoration and there are now several examples of successful large-scale restoration programs. A variety of tools and techniques have recently been developed that will improve the efficiency, cost effectiveness, and scalability of restoration programs. This review describes emerging techniques for restoration, key considerations for future programs, and highlights the benefits of increased collaboration, Traditional Owner (First Nation) and stakeholder engagement. Combined, these lessons and emerging approaches show that seagrass restoration is possible and efforts should be directed at upscaling seagrass restoration into the future. This is critical for the future conservation of this important ecosystem and the ecological and coastal communities they support.

AusTraits, a curated plant trait database for the Australian flora
Daniel S. Falster, Rachael V. Gallagher, Elizabeth Wenk, Ian J. Wright +4 more
2021· Scientific Data194doi:10.1038/s41597-021-01006-6

We introduce the AusTraits database - a compilation of values of plant traits for taxa in the Australian flora (hereafter AusTraits). AusTraits synthesises data on 448 traits across 28,640 taxa from field campaigns, published literature, taxonomic monographs, and individual taxon descriptions. Traits vary in scope from physiological measures of performance (e.g. photosynthetic gas exchange, water-use efficiency) to morphological attributes (e.g. leaf area, seed mass, plant height) which link to aspects of ecological variation. AusTraits contains curated and harmonised individual- and species-level measurements coupled to, where available, contextual information on site properties and experimental conditions. This article provides information on version 3.0.2 of AusTraits which contains data for 997,808 trait-by-taxon combinations. We envision AusTraits as an ongoing collaborative initiative for easily archiving and sharing trait data, which also provides a template for other national or regional initiatives globally to fill persistent gaps in trait knowledge.

Effects of Pesticides Monitored with Three Sampling Methods in 24 Sites on Macroinvertebrates and Microorganisms
Ralf B. Schäfer, Vincent Pettigrove, Gavin Rose, Graeme Allinson +4 more
2011· Environmental Science & Technology187doi:10.1021/es103227q

Grab water samples, sediment samples, and 2,2,4-trimethylpentane passive samplers (TRIMPS) were used to determine the exposure to 97 pesticides in 24 southeast Australian stream sites over 5 months. Macroinvertebrate communities and selected microorganisms (bacteria, flagellates, ciliates, amoebas, nematodes, and gastrotrichs) were sampled to detect relationships with pesticide toxicity. Sediment samples had the highest estimated toxicities in terms of toxic units (TU) for Daphnia magna (TUDM) and for Selenastrum capricornutum (TUSC). The pesticide-selective SPEARpesticides and the general SIGNAL index for macroinvertebrates exhibited negative linear relationships (r(2) = 0.67 and 0.36, respectively) with pesticide contamination in terms of log maximum TUDM (log mTUDM), suggesting macroinvertebrate community change due to pesticide exposure. Pesticide contamination was the only measured variable explaining variation in ecological quality. Variation in the densities of several microbial groups was best explained by environmental variables other than log TUs. The log mTUDM values derived from sediment concentrations were most important to establish a link with effects on macroinvertebrates, whereas log mTUDM of grab water samples had only minor contribution. Current-use insecticides and fungicides can affect macroinvertebrate communities and monitoring of sediment and continuous water sampling is needed to detect these effects.

Passive Sampling of SARS-CoV-2 for Wastewater Surveillance
Christelle Schang, Nicholas D. Crosbie, Monica Nolan, Rachael Poon +4 more
2021· Environmental Science & Technology169doi:10.1021/acs.est.1c01530

< 0.001) positive relationship between the concentrations of SARS-CoV-2 in wastewater and the levels found on the passive samplers, indicating that with further evaluation, these devices could yield semi-quantitative results in the future. Passive samplers have the potential for wide use in WBE with attractive feasibility attributes of cost, ease of deployment at small-scale locations, and continuous sampling of the wastewater. Further research will focus on the optimization of laboratory methods including elution and extraction and continued parallel deployment and evaluations in a variety of settings to inform optimal use in wastewater surveillance.

Estimating stand water use of large mountain ash trees and validation of the sap flow measurement technique
Rob Vertessy, Tom Hatton, P. H. Reece, Sharon O'Sullivan +1 more
1997· Tree Physiology167doi:10.1093/treephys/17.12.747

Mountain ash (Eucalyptus regnans F.J. Muell.) forest catchments exhibit a strong relationship between stand age and runoff, attributed inter alia to differences in tree water use. However, the tree water use component of the mountain ash forest water balance is poorly quantified. We have used the sap flow technique to obtain estimates of daily water use in large mountain ash trees. First, the sap flow technique was validated by means of an in situ cut tree experiment. Close agreement was obtained between the sap flow estimate of water use and the actual uptake of water by the tree from a reservoir. Second, we compared the variability in sap velocity between a symmetric and an asymmetric tree by using multiple sap flow loggers. In the symmetric tree, velocity was fairly uniform throughout the xylem during the day, indicating that accurate sap flow estimates can be obtained with a minimal number of sampling points. However, large variations in sap velocity were observed in the asymmetric tree, indicating that much larger sampling sizes are required in asymmetric stems for an accurate determination of mean sap velocity. Finally, we compared two procedures for scaling individual tree sap flow estimates to the stand level based on stem diameter and leaf area index measurements. The first procedure was based on a regression between stem diameter and tree water use, developed on a small sample of trees and applied to a stand-level census of stem diameter values. Inputs to the second procedure were tree water use and leaf area of a single tree and the leaf area index of the stand. The two procedures yielded similar results; however, the first procedure was more robust but it required more sampling effort than the second procedure.

Elevated atmospheric [CO<sub>2</sub>] can dramatically increase wheat yields in semi‐arid environments and buffer against heat waves
Glenn J. Fitzgerald, Michael Tausz, Garry J. O’Leary, Mahabubur Mollah +4 more
2016· Global Change Biology166doi:10.1111/gcb.13263

Wheat production will be impacted by increasing concentration of atmospheric CO2 [CO2 ], which is expected to rise from about 400 μmol mol(-1) in 2015 to 550 μmol mol(-1) by 2050. Changes to plant physiology and crop responses from elevated [CO2 ] (e[CO2 ]) are well documented for some environments, but field-level responses in dryland Mediterranean environments with terminal drought and heat waves are scarce. The Australian Grains Free Air CO2 Enrichment facility was established to compare wheat (Triticum aestivum) growth and yield under ambient (~370 μmol(-1) in 2007) and e[CO2 ] (550 μmol(-1) ) in semi-arid environments. Experiments were undertaken at two dryland sites (Horsham and Walpeup) across three years with two cultivars, two sowing times and two irrigation treatments. Mean yield stimulation due to e[CO2 ] was 24% at Horsham and 53% at Walpeup, with some treatment responses greater than 70%, depending on environment. Under supplemental irrigation, e[CO2 ] stimulated yields at Horsham by 37% compared to 13% under rainfed conditions, showing that water limited growth and yield response to e[CO2 ]. Heat wave effects were ameliorated under e[CO2 ] as shown by reductions of 31% and 54% in screenings and 10% and 12% larger kernels (Horsham and Walpeup). Greatest yield stimulations occurred in the e[CO2 ] late sowing and heat stressed treatments, when supplied with more water. There were no clear differences in cultivar response due to e[CO2 ]. Multiple regression showed that yield response to e[CO2 ] depended on temperatures and water availability before and after anthesis. Thus, timing of temperature and water and the crop's ability to translocate carbohydrates to the grain postanthesis were all important in determining the e[CO2 ] response. The large responses to e[CO2 ] under dryland conditions have not been previously reported and underscore the need for field level research to provide mechanistic understanding for adapting crops to a changing climate.

Class 1 integrons in benthic bacterial communities: abundance, association with Tn<i>402</i>-like transposition modules and evidence for coselection with heavy-metal resistance
Carly P. Rosewarne, Vincent Pettigrove, Hatch W. Stokes, Y. M. Parsons
2009· FEMS Microbiology Ecology161doi:10.1111/j.1574-6941.2009.00823.x

The integron/gene cassette system contributes to lateral gene transfer of genetic information in bacterial communities, with gene cassette-encoded proteins potentially playing an important role in adaptation to stress. Class 1 integrons are a particularly important class as they themselves seem to be broadly disseminated among the Proteobacteria and have an established role in the spread of antibiotic resistance genes. The abundance and structure of class 1 integrons in freshwater sediment bacterial communities was assessed through sampling of 30 spatially distinct sites encompassing different substrate and catchment types from the Greater Melbourne Area of Victoria, Australia. Real-time PCR was used to demonstrate that the abundance of intI1 was increased as a result of ecosystem perturbation, indicated by classification of sample locations based on the catchment type and a strong positive correlation with the first principal component factor score, comprised primarily of the heavy metals zinc, mercury, lead and copper. Additionally, the abundance of intI1 at sites located downstream from treated sewage outputs was associated with the percentage contribution of the discharge to the basal flow rate. Characterization of class 1 integrons in bacteria cultured from selected sediment samples identified an association with complete Tn402-like transposition modules, and the potential for coselection of heavy-metal and antibiotic resistance mechanisms in benthic environments.