Louise Weaver

• PhD
• Science leader at Institute of Environmental Science and Research

Onsite wastewater systems (OWMS) (often all referred to incorrectly in New Zealand as ‘septic tanks’) are systems designed to treat wastewater (i.e., greywater and blackwater) from individual properties, typically in areas where centralised sewerage systems are unavailable, with the effluent discharged to land within the property boundary. Although...

Aims Larvae of the black soldier fly (BSFL), Hermetia illucens, are recognized for their remarkable feeding flexibility and ability to convert a variety of organic waste streams into useful end products. Their ability to feed on both harmful and recalcitrant waste streams is thought to be due in part to plasticity in their gut microbiota, which shi...

Microbial degradation provides an avenue for the remediation of select plastic polymers contributing to the urgent environmental problem of global plastic pollution. We demonstrate the degradation of polycaprolactone (PCL) by Clonostachys rosea and elucidate its underlying molecular mechanisms. We constructed the genome of this fungal strain and mo...

Objective The World Health Organization (WHO) has declared antimicrobial resistance (AMR) as one of the top threats to global public health. While AMR surveillance of human clinical isolates is well-established in many countries, the increasing threat of AMR has intensified efforts to detect antibiotic resistance genes (ARGs) accurately and sensiti...

Wastewater treatment facilities can filter out some plastics before they reach the open environment, yet microplastics often persist throughout these systems. As they age, microplastics in wastewater may both leach and sorb pollutants and fragment to provide an increased surface area for bacterial attachment and conjugation, possibly impacting anti...

Free-living amoebae (FLA) are common in both natural and engineered freshwater ecosystems. They play important roles in biofilm control and contaminant removal through the predation of bacteria and other taxa. Bacterial predation by FLA is also thought to contribute to pathogen dispersal and infectious disease transmission in freshwater environment...

Plastic pollution in the terrestrial environment is emerging as another significant human-made threat to ecosystem function and health. Plastic contamination can range from the macro- to the nanoscale, and environmental impacts are evident at each level. Although significant knowledge gaps remain regarding the interactions between the natural envir...

Background Plastic pollution is a severe threat to marine ecosystems. While some microbial enzymes can degrade certain plastics, the ability of the global ocean microbiome to break down diverse environmental plastics remains limited. We employed metatranscriptomic data from an international ocean survey to explore global and regional patterns in mi...

Extended-spectrum beta-lactamase, AmpC, and carbapenemase-producing bacteria were isolated from raw sewage, effluent, oxidation pond water, and sediment from a wastewater treatment plant in Aotearoa New Zealand. Here, we report the assemblies of 17 isolates belonging to the species Aeromonas veronii , Aeromonas hydrophila , Enterobacter cloacae , E...

Climate change impacts are resulting in on-going drought and flood conditions from episodes of intense heavy rainfall in an isolated Māori community in Aotearoa, New Zealand. A year-long survey was undertaken to determine the microbial water quality of a spring-sourced local stream used as a secondary water source to supplement rainfall water suppl...

Groundwater is a vital ecosystem of the global water cycle, hosting unique biodiversity and providing essential services to societies. Despite being the largest unfrozen freshwater resource, in a period of depletion by extraction and pollution, groundwater environments have been repeatedly overlooked in global biodiversity conservation agendas. Dis...

Groundwater is home to a diverse range of organisms, both small and large, which form a complex ecosystem that helps to purify the water and keep it flowing smoothly. However, much of the processes that occur in this ecosystem are still a mystery and there are many important services that we have yet to fully understand. Our goal is to create a gro...

Microbial pathogen survival within the environment can be variable and can depend on many criteria, including environmental conditions e.g. oxygen concentration, temperature, pH, sunlight, etc. (e.g., Horswell et al. (2010)). Groundwater has been shown to enable the prolonged survival of pathogenic organisms due to the absence of sunlight and relat...

Herein we report the whole genome sequences of 12 highly triclosan tolerant bacteria isolated from returned activated sludge spiked with triclosan.

The widespread use of emerging contaminants (ECs) may be compounding the problem of antibiotic resistance. Various non-antibiotic pollutants have been shown to alter bacterial responses to antibiotics and increase horizontal transfer of antimicrobial resistance (AMR) genes. ECs include components of medicines, foods, disinfectants, personal care pr...

This report presents effluent quality data from 30 OWMS (of several different brands, designs, ages, treatment levels, and household occupancy levels) in Waitaha/Canterbury region in New Zealand. Although 29 different geochemical and microbiological analytes are presented, this summary report discusses phosphorus and nitrogen, as well as E. coli an...

Complex microbial communities colonize plastic substrates over time, strongly influencing their fate and potential impacts on marine ecosystems. Among the first colonizers, diatoms play an important role in the development of this 'plastiphere'. We investigated 936 biofouling samples and the factors influencing diatom communities associated with pl...

This report provides an improved identification of the location of On-site Wastewater Management Systems (OWMS) in a New Zealand context by developing a model to estimate the location of on-site wastewater systems in Canterbury region by exploring data sources from Environment Canterbury. The methodology developed utilised Geographic Information Sy...

Wastewater treatment plants (WWTPs) receive and treat large volumes of domestic, industrial, and urban wastewater containing pathogenic and nonpathogenic microorganisms, chemical compounds, heavy metals, and other potentially hazardous substances. WWTPs play an essential role in preserving human, animal, and environmental health by removing many of...

Sand filtration is a cost-effective means of reducing microbial pathogens in drinking-water treatment. Our understanding of pathogen removal by sand filtration relies largely on studies of process microbial indicators, and comparative data from pathogens are sparse. In this study, we examined the reductions of norovirus, echovirus, adenovirus, bact...

(1) Background: This paper discusses the impact of agricultural activities on stream health, particularly in relation to dairy cow fecal pollution. The study explores the fecal microbiome of cattle and the potential ecological implications of aging fecal pollution on waterways. (2) Methods: The study examines changes in the bacterial community avai...

The concept of ecosystem health is now widely used to communicate the status or condition of a natural environment and is embedded in environmental policies globally. The concept has underpinned ecological assessments for decades but has only recently been applied to groundwater ecosystems. The aim of this chapter was to provide a critical review o...

The movement of bacterial and viral pathogens through soil and vadose zone and subsequently into groundwater is a major public health concern. There are relatively few studies on the transport and fate of microbes through variably saturated vadose zone media compared with their transport in the soil and saturated groundwater zones. In this study, w...

Aquifers are populated by highly diverse microbial communities, including unusually small bacteria and archaea. The recently described Patescibacteria (or Candidate Phyla Radiation) and DPANN radiation are characterized by ultra-small cell and genomes sizes, resulting in limited metabolic capacities and probable dependency on other organisms to sur...

Groundwater is a vital ecosystem of the global water cycle, hosting unique biodiversity and providing essential services to societies. Despite being the largest unfrozen freshwater resource, in a period of depletion by extraction and pollution, groundwater environments have been repeatedly overlooked in global biodiversity conservation agendas. Dis...

The current paper discusses some selected developments for efficient management of the globally increasing quantity of waste. Incinerator bottom ash (IBA), the heavier ash generated during incineration of municipal waste, is currently utilised in two distinct ways. One pathway is not to fragment IBA and use it as a building material in road constru...

In rural environments, the sources of fecal contamination in freshwater environments are often diffuse and a mix of fresh and aged fecal sources. It is important for water monitoring purposes, therefore, to understand the impacts of weathering on detection of the fecal source markers available for mobilization from livestock sources. This study tar...

The nitrogen cycle plays a major role in aquatic nitrogen transformations, including in the terrestrial subsurface. However, the variety of transformations remains understudied. To determine how nitrogen cycling microorganisms respond to different aquifer chemistries, we sampled groundwater with varying nutrient and oxygen contents. Genes and trans...

Antimicrobial resistance (AMR) is an increasing global threat that affects human, animal and, often less acknowledged, environmental health. This complex issue requires a multisectoral One Health approach to address the interconnectedness of humans, animals and the natural environment. The prevalence of AMR in these reservoirs varies widely among c...

The ubiquity of plastic debris in marine environments raises the question, what impacts do plastics have on our marine microbiota? To investigate this, we applied bacterial 16S rRNA gene and fungal ITS2 region sequencing to identify changes in microbial biofilm community compositions on marine plastic, over time. We sampled biofilm on virgin linear...

Internationally, the environmental damage caused by the improper disposal of approximately 100 Mt of plastic waste per annum is of growing concern. Attempts to address this issue have generated many hundreds of scientific studies announcing the discovery of novel plastic-degrading microorganisms and their respective enzymes. On closer inspection, h...

The number of publications reporting putative plastic-degrading microbes and proteins is continuously increasing, necessitating the compilation of these data and the development of tools to facilitate their analysis. We developed the PlasticDB web application to address this need, which comprises a database of microorganisms and proteins reported t...

Anammox is increasingly shown to play a major role in the aquatic nitrogen cycle and can outcompete heterotrophic denitrification in environments low in organic carbon. Given that aquifers are characteristically oligotrophic, anammox may represent a major route for the removal of fixed nitrogen in these environments, including agricultural nitrogen...

Global plastic production has increased exponentially since manufacturing commenced in the 1950’s, including polymer types infused with diverse additives and fillers. While the negative impacts of plastics are widely reported, particularly on marine vertebrates, impacts on microbial life remain poorly understood. Plastics impact microbiomes directl...

Over a three-year field trial, the impacts of composted and raw gentamicin fermentation waste (GFW) application to land on residual soil gentamicin levels, physicochemical properties, bacterial community composition, and antibiotic resistance genes (ARGs) were assessed. In the saline-alkali soil tested, GFW application decreased electrical conducti...

Background Anaerobic ammonium oxidation (anammox) is important for converting bioavailable nitrogen into dinitrogen gas, particularly in carbon poor environments. Yet, the diversity and prevalence of anammox bacteria in the terrestrial subsurface – a typically oligotrophic environment – is little understood across different geochemical conditions....

Aims: Aerobic methane oxidation coupled to denitrification (AME-D) is a promising process for removing nitrate from groundwater and yet its microbial mechanism and ecological implications are not fully understood. This study used RNA stable isotope probing (RNA-SIP) and high-throughput sequencing to identify the microorganisms that are actively in...

The present study describes the development of a laboratory-scale waste stabilisation pond (WSP) system, undertaken in order to investigate the effects of hydraulic, physicochemical, microbial and physical parameters on wastewater treatment. Previous studies have focused predominantly on hydraulic characteristics. This system was engineered at a sc...

This study compared light and dark disinfection of faecal bacteria/viral indicator organisms (E. coli and MS2 (fRNA) bacteriophage) and human viruses (Echovirus and Norovirus) in Wastewater Treatment Pond (WTP) mesocosms. Stirred pond mesocosms were operated in either outdoor sunlight-exposed or laboratory dark conditions in two experiments during...

The number of plastic-degrading microorganisms reported is rapidly increasing, making it possible to explore the conservation and distribution of presumed plastic-degrading traits across the diverse microbial tree of life. Putative degraders of conventional high-molecular-weight polymers, including polyamide, polystyrene, polyvinylchloride, and pol...

Antimicrobial resistance (AMR) threatens human and ecological health worldwide. Unless major changes occur across the human, animal and environmental sectors, the problem will continue to expand. An important component of AMR that deserves greater attention is the influence of emerging organic contaminants (EOCs) – ubiquitous compounds found, among...

In tropical to temperate environments, fecal indicator bacteria (FIB), such as enterococci and Escherichia coli, can persist and potentially multiply, far removed from their natural reservoir of the animal gut. FIB isolated from environmental reservoirs such as stream sediments, beach sand and vegetation have been termed “naturalized” FIB. In addit...

The intensification of dairy farming on the agricultural landscape in New Zealand has raised concerns about pollution sources from dairy fecal runoff into waterways. An important step for mitigation of pollution is the identification of the sources of fecal contamination. An amplicon-based metagenomic assay of the bacterial community mobilised into...

Antibiotics residues have been accumulating in the environment day by day due to overuse of antibiotics. Recalcitrant antibiotic residues, such as tylosin (TYL), can cause serious environmental problems, which makes it important to eliminate TYL from the environment. It is important to eliminate TYL from the environment. In this study, a strain was...

The vast majority of microorganisms in aquifers live as biofilms on sediment surfaces, which presents significant challenges for sampling as only the suspended microbes will be sampled through normal pumping. The use of a down-well low frequency sonicator has been suggested as a method of detaching microbes from the biofilm and allowing rapid sampl...

Aim: Infiltration experiments aimed to show the effectivity of coral sand to remove micro-organisms in septic tank wastewater treatment system, in South Tarawa, Kiribati. Methods and results: Laboratory experiments evaluated effective microbial removal properties of a packed bed of coral beach sand conditioned with domestic effluent. Bacterial a...

Contamination of potable groundwater by pathogenic viruses from on-site wastewater treatment systems (OWTS) poses a serious health risk. This study investigated the attenuation and transport of rotavirus, bacteriophage MS2 and DNA-labelled-glycoprotein-coated silica nanoparticles (DGSnp) in 2 intact cores of silt loam over gravels dosed with wastew...

In New Zealand, there is substantial potential for microbial contaminants from agricultural fecal sources to be transported into waterways. The flow and transport pathways for fecal contaminants vary at a range of scales and is dependent on chemical, physical and biological attributes of pathways, soils, microorganisms and landscape characteristics...

Groundwater is a vital source of drinking water both in New Zealand and globally. Although groundwater represents a small proportion of the global water, it is a predominant source of drinking water. The perception, often, is that groundwater is a pristine, sterile environment. There are, however, a vast array of organisms thriving under our feet....

Adequate sewage treatment is essential for maintaining both New Zealand and global economic and sustainable existences. Treatment, such as pathogen removal, is required to protect the public health and the environment from anthropogenic activities. Investigating enzymatic virus removal mechanisms can aid development of pathogen removal models and i...

Aim: To compare the risk of microbial contamination of groundwater from cowpats using two irrigation practices onto pasture.

Knowledge of how effectively microbes are transported through porous media is useful for water resource/wastewater management. Despite much research having been done to characterize microbial contaminant transport through various sedimentary materials, very little study has been made on coral sand, such as constitutes the primary substrate of many...

This study describes the analysis of 432 isolates of Yersinia enterocolitica by pulsed-field gel electrophoresis (PFGE). PFGE had a high level of discrimination with biotype 1A isolates (Simpson's Diversity Index 0.997), but with the clinically important biotypes 2, 3 and 4, the discriminatory ability of PFGE was so low as to severely limit its use...

Waste disposal on land and the consequent transport of bacterial and viral pathogens in soils and aquifers are of major concern worldwide. Pathogen transport can be enhanced in the presence of organic matter due to occupation of attachment sites in the aquifer materials thus preventing pathogen attachment leading to their faster transport for longe...

Cryptosporidium parvum is a waterborne pathogen, yet no suitable surrogate has been established for quantifying its filtration removal in porous media. Carboxyl polystyrene microspheres with size, density, and shape similar to C. parvum were coated with biotin (free and containing amine, NH(2)) and glycoprotein. These biomolecules have isoelectric...

Freshly excreted Canada goose faeces pose a public health risk as they contain pathogenic microorganisms. Accordingly, a study was carried out on the growth and survival of resident indicator bacteria (enterococci and Escherichia coli) and inoculated Campylobacter jejuni in freshly excreted faeces over summer and winter. Canada goose faeces were co...

Aims: Studies to date have shown rapid killing of bacterial cells when exposed to copper surfaces. The mechanistic action of copper on bacterial cells is so far unknown. Methods and Results: To investigate potential mechanisms involved, meticillin-resistant Staphylococcus aureus (MRSA) cells (107 CFU) were inoculated onto coupons of copper or stain...

Aims: As copper has been previously suggested as an antimicrobial surface, we tested the effectiveness of copper as an antifungal surface which could be used in air-conditioning systems as an alternative to aluminium. Methods and results: Coupons of copper (C11000) and aluminium were inoculated with fungal isolates (Aspergillus spp., Fusarium sp...

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Clostridium difficile is rapidly becoming a major cause of hospital-acquired infections worldwide, due in part to transmission of the faecal pathogen between contaminated hands and contact surfaces. Accordingly, this study evaluated survival of C. difficile vegetative cells and spores on the contact surface commonly found in healthcare settings, st...

Eleven flavonoid derivatives were synthesised using a modified Baker-Venkataraman rearrangement, and subsequent microwave-assisted closure of the heterocyclic ring. All of the synthetic compounds displayed antifungal activity against Aspergillus niger and Fusarium oxysporium, and two of the synthetic flavonoid analogues exhibited significant activi...