Native plants may be weapon against soil contamination

New Zealand’s native plants may help to reduce bacterial contamination caused by dairy effluent, a new study suggests.

Researchers from the Bio-Protection Research Centre, ESR, and the University of Canterbury have shown northern rātā (Metrosideros robusta) and swamp mānuka (Leptospermum scoparium) can reduce the amount of Escherichia coli (E. coli) in soil by 90%, compared with ryegrass (Lolium perenne), and in less than one-third of the time. They worked in partnership with Ngaa Muka Development Trust and Matahuru Marae in Waikato.

The research, published in Applied Soil Ecology, aimed to investigate the antimicrobial properties of New Zealand native plant extracts and test if they were effective in soil. Continue reading

Study finds climate change throws tree seeding out of sync

Climate change is negatively affecting tree reproduction by throwing seed production systems out of synchronisation, according to a new international study co-authored by a University of Canterbury scientist.

Many tree species worldwide produce large seed crops at irregular intervals, known as mast seeding. New Zealanders are probably already aware of this because in three of the last six years (2014, 2016 and 2019) the Department of Conservation has had to run extensive pest control operations over very large areas, says University of Canterbury Professor Dave Kelly, School of Biological Sciences, a co-author on the study.

The pest control was required to protect rare native birds from booming populations of two key predators, rodents and stoats, which increased after big seed crops in southern beech (Nothofagus) forests. Continue reading

Canterbury University researcher aims at turning food waste into bioplastics

An ingenious new solution being engineered at the University of Canterbury (UC) aims to turn food waste into valuable chemical components that could be used to make bioplastics.

At UC’s Department of Chemical and Processing Engineering, Dr Alex Yip is leading research into food waste conversion. He is working collaboratively with Hong Kong Polytechnic University to design and develop a catalyst to achieve this.

“The ultimate objective is to produce a high-value product from food waste,” Dr Yip says. “To date, we have completed a proof-of-concept showing that it’s feasible.”

The project’s goal is to extract three key chemical components, including polylactic acid (PLA) and the organic compound 5-HMF, from the food-waste-stream. These could then be used as building blocks to make sustainable bioplastics with various properties to suit consumer needs. Continue reading

Biodegradable coating to help achieve food security

A University of Canterbury biotechnologist’s biodegradable coating can help achieve food security in an environmentally friendly and consumer-conscious way.

Biotechnology expert Associate Professor David Leung, in Te Rāngai Pūtaiao | UC College of Science, is working on a nontoxic, biodegradable coating to protect edible plants against diseases, pests and environmental hazards, including the effects of climate change.

The research could prove vital in protecting plant food without compromising consumer health. Because the coating is biodegradable, it would also provide an environmentally sustainable solution and avoid the negative impacts of agrochemicals commonly used to protect plants.

In addition to being eco-friendly, the coating is nontoxic, which Associate Professor Leung says is key to protecting the people consuming the end product.

“It is counterproductive to protect plants using toxic methods. Even though you may provide security for a food source, you are still missing the mark if you have contaminated the environment you are growing the plants in during the process and delivering a food product with toxic residues,” says Associate Professor Leung.

“It’s not just the quantity of food that we care about; it is also about producing safe food that doesn’t harm the surrounding environment.”

Non-degradable pesticides, herbicides and biocides can damage the surrounding environment by contaminating soil, water, turf and other vegetation. Although they are effective in killing insects, they can be toxic to a host of other organisms, including humans.

“There is a demand for environmentally sustainable ways of doing things and, in food production, it is important because we cannot continue using these chemicals without causing major, long-term harm to the planet,” Associate Professor Leung says.

“We believe the public, the people consuming the food, will appreciate this option because it is safer and more environmentally friendly.”

Associate Professor Leung explains that if toxic chemicals are used to protect crops over a long period, those substances will destroy the surrounding elements, which are critical to supporting the plant’s life process. Furthermore, toxic residues can accumulate in the local environment, resulting in long-term damage to the ecosystem.

“Copper sulfate is a classic case. For example, the avocado industry – without copper sulfate, there is no avocado industry.”

Avocados are just one example of fruits and vegetables protected using chemicals such as copper sulfate. A variety of agrochemicals is used every day to harvest nearly all of the world’s commercial produce.

“Right now, we have to use these undesirable substances or we simply would not be able to harvest enough food to support the world’s needs. This is why we need to have another option – a safer and more sustainable option.”

Potentially harmful substances are not only used during harvesting but also are applied to protect food being stored and shipped to overseas markets. The coating will also be adaptable to protect foods post-harvesting.

“This biodegradable coating can also be adapted to solve post-harvest challenges, including storage and shipping.”

Additionally, a large amount of food around the world is wasted due to improper storage, another problem that the biodegradable coating has the potential to address.

According to the Food and Agriculture Organization of the United Nations, “roughly one third of the food produced in the world for human consumption every year – approximately 1.3 billion tonnes – gets lost or wasted”.

Associate Professor Leung agrees.

“Food spoilage is a serious problem and this could potentially be used to combat that. This is another real-world impact we are thinking about.”

The research began after Associate Professor Leung was awarded a Tech Jumpstart Award grant in 2017, as part of UC’s annual competition that helps researchers turn their ideas into commercial reality. The project is funded until October 2019 and, while he has already created a useable solution, Associate Professor Leung hopes to acquire more funding to keep building on his current idea.

Associate Professor Leung is continuing to evolve the coating into one that will have broad use in the agricultural industry. In conjunction with the UC commercialisation team, he is working on further improving the coating to make it as appealing to investors as possible, an important step in bringing his work to the public.

“We have already come up with a patentable formulation, however, we are continuing to work on enhancing it to ensure the most effective and impactful product is brought to market.”

Source:  University of Canterbury

Embrace gene editing, says University of Canterbury’s newest Professor Emerita

New Zealand will have to seriously consider gene editing to improve crop production if it is to meet future sustainability targets, according to the University of Canterbury’s newest Professor Emerita, plant biologist Paula Jameson.

Professor Jameson recently received the honorary title of Emerita Professor, which is awarded to an outstanding academic on her retirement. But she is still very much contributing to the field of cytokinins, one of the plant growth hormones, that has defined her career.

Speaking from Yantai University in China, where she is a part-time Distinguished Professor for the next three years, Professor Jameson says Aotearoa New Zealand legislation needs to urgently catch up to other countries. Continue reading

Canterbury University scientists involved in intermittent rivers study

University of Canterbury scientists are part of a global research collaboration into the environmental impacts of dry riverbeds, with their findings published today in a new paper in one of the world’s top scientific journals (see AgScience report HERE).

New Zealand researchers, Professor of Freshwater Ecology Angus McIntosh and Dr Catherine Febria, of the School of Biological Sciences, UC College of Science, have been part of a global team from 22 countries evaluating what happens to plant litter that falls into in river beds when they are dry (i.e. not flowing).

They co-authored the paper titled ‘A global analysis of terrestrial plant litter dynamics in non-perennial waterways’ which was published today in Nature Geoscience.

“People might feel that a pile of plant litter accumulating in a dry river bed couldn’t possibly contribute to global climate warming, but the surprising reality is it very likely is,” Professor McIntosh says.

The contributions of drying rivers haven’t been included in global carbon accounting previously and their CO2 effects  could be significant.

“This is especially important because, surprisingly, intermittent streams and drying rivers are thought to include more than 50% of the river length world-wide,” he says.

Dr Febria says it is known that when rivers dry up fish and insects die, and the whole food web of the river collapses.

“However, we haven’t previously appreciated the significance of all the decomposition that happens when the water comes back. The amount of carbon dioxide released in many cases is huge,” she says.

“We should all care about this because carbon dioxide in our atmosphere is the driver of global climate warming.

“Our research indicates that increasingly drying rivers, along with other land use changes, are contributing to global climate warming. Moreover, climate warming in many places like Canterbury is predicted to increase the frequency and magnitude of drought which could also cause more river drying.

“That is a really worry because that could form a positive feedback cycle by releasing even more carbon dioxide.”

This is the first piece of research published from this collaborative study involving 94 international partners from 22 countries studying the dry beds of 212 rivers from round the world, including Canterbury.

Until recently, drying and intermittent rivers had been largely ignored. This global study is beginning to reveal they really are very important and should not be ignored.

Such extensive global research efforts have traditionally been rare. That a very large group of researchers from around the world, led by a group in France, have come together to contribute is really quite significant, Professor McIntosh says.

He didn’t expect the magnitude of emissions to be so high. Therefore the findings should force a rethink of how the global carbon models are made so that they include CO2 emissions from intermittent rivers.

Source: University of Canterbury

Urban sprawl and climate change make NZ more inviting for nastier mosquitoes

Urban sprawl and development combined with climate change mean New Zealand is troubled by more foreign, disease-carrying mosquitoes, the New Zealand Herald reports.  

It cites a University of Canterbury study which looked at how mosquito numbers and species might change as the planet warmed – and how shifts in land use could affect the picture.

Biosecurity officials recently found exotic culex mosquitoes – known to carry the feared Ross River virus – in the Kaipara Harbour this month, the newspaper noted.

The researchers specifically investigated how mosquitoes were affected by differences in land cover and climate.

“We looked at two species that are commonly found here in New Zealand and which people are probably familiar with as they are trying to get to sleep: Culex pervigilans, which is a native mosquito, and Aedes notoscriptus, a stripy-legged Australian invader,” study author Sophie Hunt said.

Mosquitoes spend the early stages of their life cycles in standing water habitats, such as ponds, puddles and water containers.

The researchers found that climate and land use affected both how suitable mosquito habitats were, and how many of them there were in place.

Warmer habitats made mosquitoes and the other insects living in the water eat more, faster, and go through their life cycles faster.

“At the same time, warmer water means the predators also eat more, faster,” said Ms Hunt, who collaborated on the study with Canterbury colleagues Dr Mark Galatowitsch and Professor Angus McIntosh.

“We found that different mosquito species react slightly differently to the change in temperature, and to predation.”

The effects were more pronounced when land use was taken into account.

“There are more, smaller, warmer habitats available in human-modified environments, and these are also less likely to contain other insects that might be predators of mosquitoes.”

As we changed the land and our climate, many foreign species were on the rise and many native ones were declining.

Some of the new species, such as mosquitoes, may bring disease.

But Ms Hunt says people have an element of control and can create habitats that support predatory insects which act as natural biocontrols against mosquitoes.

“And not all mosquitoes are bad – most of the New Zealand native ones don’t even bite humans, and they can act as pollinators.”

New Zealand is home to 15 mosquito species, 12 of which aren’t found anywhere else in the world.

Several new species have become permanently established here, dozens more have been stopped at our ports, and one has been eradicated.

Sophie Hunt completed her MSc in 2015. Her research focused on investigating effects of interacting global change drivers on native and exotic mosquito distributions.

The New Zealand Herald report is based on a University of Canterbury press statement (HERE).


Experts comment on NZ research linking herbicides to antibiotic resistance

University of Canterbury researchers have found the active ingredients in commonly-used weed killers can cause bacteria to be less susceptible to antibiotics.

The study builds on research published in 2015 that found three common herbicides caused E.coli and Salmonella to become less sensitive to antibiotics.

The new research investigated which ingredients were responsible and found it was the active ingredients to blame.  The researchers suggest regulators should consider these impacts when considering whether such products are safe to use.

They confirmed that the active ingredients of the herbicides, RoundUp, Kamba and 2,4-D (glyphosate, dicamba and 2,4-D, respectively), each alone cause antibiotic resistance at concentrations well below label application rates.

UC Molecular Biology and Genetics Professor Jack Heinemann, of the School of Biological Sciences, in UC’s College of Science, says the key finding was that “bacteria respond to exposure to the herbicides by changing how susceptible they are to antibiotics used in human and animal medicine.”

Professor Heinemann says the herbicides are among the most common manufactured chemical products to which people, pets and livestock in both rural and urban environments are exposed. They are sold in local hardware stores and may be used without training, and there are no controls that prevent children and pets from being exposed in home gardens or parks.

The new paper also finds the inert ingredients (surfactants) that are commonly used in some herbicide formulations and processed foods also cause antibiotic resistance.

The study found an antibiotic resistance response was caused by both the tested surfactants, Tween80 and CMC. Both are also used as emulsifiers in foods like ice cream and in medicines, and both cause antibiotic resistance at concentrations allowed in food and food-grade products.

With expertise in genetic engineering, bacterial genetics and biosafety, Professor Heinemann has some recommendations:

“The sub-lethal effects of industrially manufactured chemical products should be considered by regulators when deciding whether the products are safe for their intended use,” he says.

“More emphasis needs to be placed on antibiotic stewardship compared to new antibiotic discovery. Otherwise, new drugs will fail rapidly and be lost to humanity.”

The researchers first observed this antibiotic resistance in their paper published in the American Society of Microbiology’s journal mBio in 2015. This follow-up study was conducted in order to identify which ingredients in herbicides were responsible.

Antibiotic resistance is the cause of nearly a million additional deaths worldwide from infectious diseases, Professor Heinemann says.

“The United States, for example, estimates that more than two million people are sickened every year with antibiotic-resistant infections, with at least 23,000 dying as a result. By 2050, resistance is estimated to add 10 million annual deaths globally with a cumulative cost to the world economy of US$100 trillion. In other words, roughly twice the population of New Zealand will be lost annually to antibiotic resistance.”

Herbicides are chemicals used to control weeds. Because they kill organisms, they are biocides. As their primary purpose is to kill plants, their effects on some non-target organisms are not as well studied.

Antibiotics are also biocides. Antibiotic resistance allows bacteria that previously could be controlled by antibiotics to continue to cause disease and remain infectious for longer, even in the presence of antibiotics. Resistance to at least one major clinical antibiotic is now found in all human pathogens, and some important pathogens can be resistant to all but one antibiotic, or even all antibiotics. Even in wealthy countries, antibiotic resistance is responsible for billions of dollars of increased health care costs, additional suffering and tens of thousands of deaths each year.

Many biocides have effects on either target or non-target organisms at concentrations that do not kill. These are called sub-lethal effects. When pesticides, including herbicides, are reviewed for their safety by regulators, the focus is on acute and sometimes chronic toxicity using mortality as an endpoint. Much less information is sought on potential sub-lethal effects, particularly for microbes.

The Science Media Centre gathered expert reaction to the paper –

Dr Heather Hendrickson, Senior Lecturer in Molecular Bioscience, Massey University, comments:

“We are living in a microbial world and we have been affecting that world in ways that we have not fully grasped for much of the industrial era. Antibiotics are the set of drugs that we use to kill or disable bacterial pathogens that make us ill. Today, these important medicines are becoming less effective around the globe as bacteria become resistant to them due to our overuse.

“This new paper by Kurenbach et al. is an attempt to understand the effects that some common Herbicides (weed killers) may be having on a set of the microbial multitudes in our soils.

“This paper follows up on the foundational work published in 2015 by the last author, Jack Heinemann, which found that herbicide exposure could change the ability of some bacteria to survive antibiotic exposure. Here, the mechanism of some of the antibiotic effectiveness appeared to be protein pumps called efflux pumps in the bacteria. Bacteria exposed to herbicide start to make these pumps and install them like bilge pumps that purge the herbicides rapidly. Antibiotics can then be jettisoned along with the herbicides when both are present.

“The results of these two studies are not simple but they are worthy of public note for the following reasons:

  1. Exposure to commonly-used herbicides have effects on microbes that can make the bacteria more likely to be killed by some antibiotics but also less likely to be killed by other antibiotics.
  2. The microbes used here was a pair of bacteria, Salmonella enterica and Escherichia coli, both of which can be human pathogens. These are both on the 2017 WHO bacteria for R&D into new antibiotics list as Priority 1 ‘critical concern’.
  3. The antibiotics used in this study were clinically-relevant antibiotics that we are using in human medicine today like ciprofloxacin and kanamycin.
  4. The herbicides used in this study are available widely and there is little current regulation on their use.
  5. It was the active ingredients in the herbicides (not the extra, ‘co-formulant’ additives) that had the greatest effects on antibiotic effectiveness.
  6. The concentrations of herbicides and antibiotics used in this study were within ranges that might be experienced by bacteria we encounter daily.

“The message from the paper is clear, we need to reconsider our use of herbicides in light of the effect that they are having on the microbial world.”

Dr Siouxsie Wiles, Microbiologist and Senior Lecturer, University of Auckland, comments:

“This paper is very timely, as this week is World Antibiotic Awareness Week in which the World Health Organization, the Ministry of Health, the Royal Society Te Apārangi and others are raising awareness of the crisis of antibiotic resistance. Antibiotics are losing their ability to kill bacteria. This means that we face a future in which routine surgery and medical treatments such as chemotherapy will be life-threateningly risky, and common infections untreatable. This crisis is caused in part because bacteria are able to mutate to become resistant to antibiotics, and because the discovery of new antibiotics has ground to a halt over the last few decades.

“This paper by Professor Jack Heinemann and his colleagues builds on their earlier work looking at the impact of pesticides on bacteria. Now they have shown that exposure of two common gut bacteria to commercial pesticide formulations and some of their active ingredients can change how much antibiotic is needed to kill the bacteria. The bacteria they have examined (Salmonella Typhimurium and Escherichia coli) are both able to infect humans and other animals, including farm animals.

“Prof Heinemann’s findings show how complex biology and the microbial world are. Some of the ingredients made the bacteria more sensitive to some antibiotics, and others made them less sensitive to antibiotics. Fortunately, the type of resistance Prof Heinemann and his colleagues found is not the type that can transfer from one species of bacteria to another, but it is clearly still cause for concern.

“For me, their most striking finding was that surfactants, which are inert ingredients commonly used in all sorts of products, also increased resistance of the bacteria to various antibiotics. This means that it’s likely that many of the products we routinely use in our environment, our homes and on our bodies, may be contributing to making some bacteria more difficult to treat with antibiotics. With the crisis we are facing, that’s a real worry.”

Lecturer to discuss science, junk science and how to tell the difference


How do we tell the difference between science, pseudo-science, anti-science rhetoric and ‘alternative facts’?

The University of Canterbury, announcing a lecture on the topic (HERE), quotes the famous astrophysicist, Carl Sagan:

“We live in a society exquisitely dependent on science and technology in which hardly anybody knows anything about science and technology”.

Then the university raises another question: why is the language of science and scientific achievement often viewed with suspicion and, at times, derision?

In the upcoming UC Connect public lecture Science, junk science, and how to tell the difference, Adjunct Professor Simon Pollard will talk about the rewards and frustrations of communicating science to a wide audience.

Dr Simon Pollard is Adjunct Professor of Science Communication at the University of Canterbury. He is a spider biologist and award-winning writer and photographer. He has been involved in contributing to the public understanding of science through writing, exhibitions, lectures and advising on natural history documentaries for 25 years.

He has been an advisor on three Attenborough BBC series; most recently The Hunt in 2015.

In 2016, he spent two days a week in Wellington as the external science advisor to Te Papa and Weta Workshop on the $5 million exhibition Bug Lab. Currently, he is writing a book for Te Papa Press on New Zealand natural history for younger readers.

UC Connect public lecture: Science, junk science, and how to tell the difference, Adjunct Professor Simon Pollard, 7pm on Wednesday 19 July at the University of Canterbury.

Register to attend free HERE.

Sustainable agriculture — getting more for less from fertilisers

New research by University of Canterbury Biological Sciences PhD students Jessica Roche and Qianqian Guo is throwing light on how plants such as ryegrass take up and use nitrogen during the grazing cycle.

Farmers are increasingly looking for ways of using fertilisers in a more sustainable way as awareness grows about the negative environmental effects associated with intensive use of nitrogen fertilisers.

Nitrogen is critical to plant growth and reproduction, but the downsides of intensive use include nitrous oxide emissions and nitrate runoff into waterways.

Current estimates are that only 30–40% of applied nitrogen is used by plants. Understanding how uptake and assimilation processes work therefore is critical in the quest to find more efficient ways to apply nitrogen.

Ballance Agri-Nutrients, working with the university, provided funding for the new research.

For growers and farmers, a key question is whether the use of nitrogen fertilisers can be reduced without compromising production.

“Or to put it another way, can greater production be achieved with lower inputs? The goal for sustainable agriculture is to get more out for less,” says Professor Matthew Turnbull, who heads the UC School of Biological Sciences.

“What we’ve been trying to do, in association with Ballance Agri-Nutrients, is to start exploring this question by looking at the process of what happens to plants when you add large amounts of nitrogen, in terms of the uptake in roots and incorporation of nitrogen in the form of organic compounds in the plant.”

The PhD research has found a critical link between the physiological state of pasture directly after grazing and the ability of that pasture to effectively take up nitrogen fertiliser.

Soon after grazing, ryegrass plants tend to have very little stored sugar. It is precisely these sugars that are needed for nitrogen to be taken up from the soil and converted into amino acids and proteins.

So, adding fertiliser too soon after grazing may result in a relatively poor uptake of nitrogen.

“We have ongoing work to investigate and identify the right timing for adding nitrogen. Is there a sweet spot? We suspect there probably is one, somewhere within that first week or two after grazing when the pasture has recovered yet still has that potential to grow fast with the addition of fertiliser.”

Most of the students’ work, which has also been supervised by Professor of Biology Paula Jameson, has been laboratory-based using hydroponic systems to enable close control of nitrogen input and to make it easier to study the process of nitrogen uptake by plants.

Professor Turnbull said the research would help inform the work of Ballance Agri-Nutrients on the farm.