PubMed | Canadian Food Inspection Agency, University of Lethbridge, Alberta Agriculture and Forestry and Agriculture and Agri Food Canada
Type: Journal Article | Journal: Journal of applied microbiology | Year: 2016
The suitability of composting for disposal of livestock mortalities due to Bacillus anthracis was assessed by measuring viability of surrogate spores from two strains each of Bacillus licheniformis and Bacillus thuringiensis after a heating cycle modelled on a cattle composting study.Sporulation was attempted from 10 to 37C, but poor yields at lower temperatures resulted in 25, 30 and 37C being selected to generate sufficient spores (8log10 CFUml(-1) ) for experiments. Spores were inoculated into 3g autoclaved dried-ground compost rehydrated with 6ml water or silica beads in a factorial design for each strain, sporulation temperature, matrix and sampling day (0, 25, 50, 100, 150). Maximum incubation temperature was 62C, but spores were maintained at 55C for 78 of 150days. Although significant differences existed among Bacillus strains and sporulation temperatures, numbers of viable spores after 150days averaged 13log10 CFUg(-1) , a 52log10 reduction from day 0.Spore inactivation was likely due to heat and desiccation as matrices were autoclaved prior to incubation, negating impacts of microflora.Results support composting for disposal of anthrax mortalities, provided long-term thermophillic heating is achieved. Due to limited sporulation at 10C, livestock mortalities from anthrax at this or lower ambient temperatures would likely be of lower risk for disease transmission.
Evaluation of Various Campylobacter-Specific Quantitative PCR (qPCR) Assays for Detection and Enumeration of Campylobacteraceae in Irrigation Water and Wastewater via a Miniaturized Most-Probable-Number-qPCR Assay
PubMed | University of Alberta, University of Calgary, Water Quality Services, Alberta Agriculture and Forestry and Public Health Agency of Canada
Type: Journal Article | Journal: Applied and environmental microbiology | Year: 2016
Campylobacter spp. are the leading cause of bacterial gastroenteritis worldwide, and water is increasingly seen as a risk factor in transmission. Here we describe a most-probable-number (MPN)-quantitative PCR (qPCR) assay in which water samples are centrifuged and aliquoted into microtiter plates and the bacteria are enumerated by qPCR. We observed that commonly used Campylobacter molecular assays produced vastly different detection rates. In irrigation water samples, detection rates varied depending upon the PCR assay and culture method used, as follows: 0% by the de Boer Lv1-16S qPCR assay, 2.5% by the Van Dyke 16S and Jensen glyA qPCR assays, and 75% by the Linton 16S endpoint PCR when cultured at 37C. Primer/probe specificity was the major confounder, with Arcobacter spp. routinely yielding false-positive results. The primers and PCR conditions described by Van Dyke et al. (M. I. Van Dyke, V. K. Morton, N. L. McLellan, and P. M. Huck, J Appl Microbiol 109:1053-1066, 2010, http://dx.doi.org/10.1111/j.1365-2672.2010.04730.x) proved to be the most sensitive and specific for Campylobacter detection in water. Campylobacter occurrence in irrigation water was found to be very low (<2 MPN/300 ml) when this Campylobacter-specific qPCR was used, with the most commonly detected species being C. jejuni, C. coli, and C. lari Campylobacters in raw sewage were present at 10(2)/100 ml, with incubation at 42C required for reducing microbial growth competition from arcobacters. Overall, when Campylobacter prevalence and/or concentration in water is reported using molecular methods, considerable validation is recommended when adapting methods largely developed for clinical applications. Furthermore, combining MPN methods with molecular biology-based detection algorithms allows for the detection and quantification of Campylobacter spp. in environmental samples and is potentially suited to quantitative microbial risk assessment for improved public health disease prevention related to food and water exposures.The results of this study demonstrate the importance of assay validation upon data interpretation of environmental monitoring for Campylobacter when using molecular biology-based assays. Previous studies describing Campylobacter prevalence in Canada utilized primers that we have determined to be nonspecific due to their cross-amplification of Arcobacter spp. As such, Campylobacter prevalence may have been vastly overestimated in other studies. Additionally, the development of a quantitative assay described in this study will allow accurate determination of Campylobacter concentrations in environmental water samples, allowing more informed decisions to be made about water usage based on quantitative microbial risk assessment.
News Article | November 18, 2015
In a pasture outside Edmonton, Canada, you’ll find a few dozen cows doing what cows do: mostly eating. The average animal spends eight-plus hours a day filling its belly, or as is the case with cows, bellies. Along with that enormous appetite, cows are born with the ability to digest almost any plant they can chew, thanks to a multichambered stomach and a helpful army of gut microbes that break down food that most mammals cannot. The system is an evolutionary bonanza for cattle, but it’s not so easy on the environment — which is why the animals at the Lacombe Research Centre are no ordinary grazers. Through a transponder clipped to the ear of each cow, scientists record when a cow sticks her head into a bin of tasty feed pellets. As she eats, a solar-powered fume hood above captures her exhalations. Laser beams surround the pasture, reading gases in the atmosphere. Livestock is a major source of methane emissions from human activity in the United States. The gas is produced as part of the digestive process of cattle and other ruminants and from microorganisms that grow in manure (numbers in chart at top are rounded). Source: Inventory of U.S. greenhouse gas emissions and sinks: 1990–2013/EPA 2015 All this fuss is over bovine burps. While cattle and other ruminants like sheep and goats have been gassy for around 50 million years, scientists have only recently begun to pay keen attention to their exhaust as concern grows over climate change. The belches contain methane, an odorless compound that is the main component of natural gas. In the atmosphere, methane warms the Earth. It isn’t the most abundant greenhouse gas created by human activity (that prize goes to carbon dioxide), but methane is one of the most powerful at trapping heat. In a “pound for pound” comparison, over a century, methane has an impact on climate change that is 25 times as great as CO , according to the U.S. Environmental Protection Agency. Citing methane’s impact, a recent CNN story referred to beef as “the new SUV.” But the old SUVs, along with the rest of the oil and gas industry, are a larger source of atmospheric methane in the United States, EPA data indicate, contributing 29 percent of U.S. methane emissions. Livestock is responsible for 26 percent, the agency estimates. Yet while that’s the official number, a paper last year in the Journal of Geophysical Research: Atmospheres raised the possibility that the EPA’s measurements are off, and that the biggest source of methane from human activity may in fact be ruminants — more than 90 percent of them cows raised for beef and dairy production. While methane emissions from the energy sector declined between 1990 and 2013, the contribution from agriculture rose by 11 percent, according to the EPA. (Though in later years cattle populations fell and so did livestock-related methane.) The World Bank estimates that overall global methane emissions rose 17 percent between 1990 and 2010. In 2014, the U.S. government announced a goal to reduce methane output from dairy cattle by 25 percent by 2020. That’s why scientists worldwide are looking for ways to produce a less noxious cow. Experiments target the animal inside and out, testing variations in feed, antimethane additives and experimental vaccines. The Canadian project goes deeper, using genetics to develop and breed animals that are naturally less burpy. All approaches are promising, but no single one has hit the sweet spot: reducing methane dramatically while not harming the cow or dampening production of farms and ranches. Any solution can’t be too impractical or too expensive, either. The good news is that this is one issue where the interests of the $44 billion beef industry and environmentalists may converge — cattle that pollute less might live longer or get by with less feed, improving the profit margins of farms and ranches. “We’ve been selling the greenhouse gas story as a win-win to farmers,” says Conrad Ferris, head of dairy research at the Agri-Food and Biosciences Institute in Hillsborough, Northern Ireland. Most methane-reducing experiments don’t concern the cow per se; they go after the microscopic ecosystem huddled inside the animal’s gut. When a cow eats, hay, grass and other plant material land inside the rumen, the largest of the four compartments of the bovine stomach, which can hold 150 to 190 liters of food and water. Ruminant digestion is a microbial marvel: A portion of the stomach is sectioned off into a sophisticated vat for fermentation, which occurs when microorganisms slice sugar and other large molecules into smaller ones. (Without fermentation, grapes and agave couldn’t become wine and tequila.) Trapped inside the rumen, bacteria digest the components of the forage, especially cellulose, the large chains of glucose that form the main structural support of the cell walls of plants. Cellulose is the reason green plants tend to be stiff and rigid. People aren’t born with the enzymes to cope with cellulose, which is why we don’t eat grass. When humans eat foods such as fruits and vegetables, the cellulose acts as dietary fiber. Because it resists digestion, cellulose doesn’t provide energy. It does help a person feel full with fewer calories and maintain the health of the intestine, and of the microbiome inside. Thanks to a multichambered stomach and helpful microbes, cattle can digest food that humans cannot. The largest chamber, the rumen, is a fermentation vat that breaks down cellulose. Microbes soak up the resulting hydrogen, producing methane (CH ), which the cow releases, mainly in burps. But a ruminant animal’s microorganisms can extract the energy locked up in cellulose. Its digestive system includes microbes called methanogens, ancient entities distinct from bacteria and other microorganisms. Methanogens can live in other oxygen-starved environments, such as the bottom of lakes. When microbes in the rumen digest cellulose, they leave behind nutrients that the cow needs plus methane gas, created when methanogens soak up the hydrogen left over from fermentation. The relationship is straightforward: The more the cow eats, the more it ferments, the more methane produced. Emissions from a grown dairy cow can amount to about 260 to 650 grams of methane per day. Consider that the nation has 98 million head of cattle and you see the scope of the problem. One mid-sized animal could put out about 150 kilograms of methane every year, which has the same environmental impact as driving from New York to Los Angeles — three times. Scientists are trying to interfere with the chemical steps that lead to methane production in ways that don’t harm the overall health or productivity of the cows. Over the last few years, researchers have tried adding natural and laboratory-made substances to cow feed. One of them is nitrate. The idea is that, given the extra nitrogen, methanogens sopping up excess hydrogen will form ammonia (composed of one nitrogen and three hydrogen atoms) instead of methane (one carbon and four hydrogens). Last year, scientists from the Lethbridge Research Centre in Canada, writing in the Canadian Journal of Animal Science, reviewed nitrate-adding experiments dating back to the 1960s. Some laboratory tests yielded dramatic results, reducing cow methane emissions by as much as 70 percent. In other studies, the nitrate didn’t affect the growth or appetite of the cows, or milk or meat production. Problem is, in the rumen, nitrate is broken down into nitrite, which can interfere with the action of red blood cells. One cow died in an experiment and six others had to be rescued. “One of the challenges is, how do you deliver it in a way that prevents nitrate toxicity in the animal,” says Wendy Powers, director of environmental stewardship for animal agriculture at Michigan State University in East Lansing. Other scientists have experimented with plants that can influence microbes and change the methane-producing chemistry of the rumen, with the hope that “the public will more readily accept something that is natural,” says Alexander Hristov, a professor of dairy nutrition at Penn State University. He and his colleagues added a by-product of cashew nut processing to feed and reduced methane emissions by a modest 8 percent, they reported in June in the Journal of Dairy Science. He has also experimented with adding oregano to feed, which reduced methane. But it got to be too much. “We were feeding 500 grams of oregano per cow per day,” he says. “That is not going to be economical.” Different approaches are under study to reduce bovine methane emissions. Most try to change the chemistry or microbial makeup of the rumen. Promotes formation of ammonia instead of methane Alters the chemistry of the rumen Substitutes feed that relies less on fermentation Increases milk production in dairy cows; already available Can be expensive; environmental cost if transportation needed Blocks enzyme that drives last step of methane formation In one experiment, methane dropped 30 percent and cows gained weight Cows require less feed for same growth Changes are slow; may affect other traits, such as health or fertility Sources: C. Lee and K.A. Beauchemin/Can. J. Anim. Sci. 2014; G. Wischer et al/Animal 2013; H.P. Jiao et al/J. Dairy Sci. 2014; A.N. Hristov et al/Proc. Natl. Acad. Sci. 2015; M. Aspin; J.A. Basarab et al/Animal 2013 Powers mentored a Michigan State grad student who tried adding an extract from tea to feed, which raised yet another complication: “You had to get so much in there to be effective, palatability became an issue,” she says. Cows will shun a solution that tastes bad. Overall, she says, experiments with various plant extracts have been inconsistent. Hristov’s team devised another approach that appears to pass the taste test. Researchers experimented with a synthetic feed additive designed to interfere with an enzyme that drives the last step of methane formation. In the Aug. 25 Proceedings of the National Academy of Sciences, the researchers reported that 48 cows given the additive for 12 weeks produced 30 percent less methane than cows that ate only their normal feed. The additive did not affect the animals’ appetite or milk production. “This is the most promising feed additive we have worked with,” Hristov says. “In my opinion, this is the answer to the gut problem.” The Irish scientists are also trying to reduce methane by decreasing the proportion of roughage (the grass and hay that leads to methane production) and increasing the amount of concentrates, which are plants that are easier to digest without fermentation, such as corn and soybeans. Last year, in the Journal of Dairy Science, the researchers described one such experiment in 40 grazing cows. As concentrates increased, so did milk production. The cows’ overall methane emissions weren’t affected, but with higher production, the amount of methane that accompanied each liter of milk was reduced, which eases the environmental impact. That experiment was on animals in the field. Experiments in barns have also demonstrated that more concentrates mean less methane per liter of milk produced, Ferris says. But concentrates are costly. “There comes a point when even the higher milk production doesn’t cover the cost of concentrates,” he says. Also, if the overall goal is to ease the impact on the environment, the production and shipping of concentrates has its own carbon footprint. A concern with food additives is that the methanogens in the rumen might adapt to their new diet after a time and resume methane production at the same level. For that reason, an additive would probably need to be repeatedly fed and monitored through the animal’s life span, potentially adding to cost and labor, says Mark Aspin, manager of the Pastoral Greenhouse Gas Research Consortium in Wellington, New Zealand, which partners with the government research agency AgResearch. Researchers in New Zealand — a country with more cows than people — are developing an antimethane vaccine that could reduce the population of methanogens in the rumen without affecting an animal’s weight, milk production or breeding. The advantage of a vaccine, Aspin says, is that it could theoretically be administered just once, or at least only annually. Also, farmers and ranchers are used to vaccinations; adding one more shot wouldn’t be much of a burden on existing agricultural practices. It could be used across other economically important ruminants, such as sheep (which outnumber his country’s human population 7-to-1), he says. The technology is still far from the farm, however. The New Zealand research team has identified antibodies to the gut microbes and is in the process of amplifying the important pieces of those antibodies and incorporating them into a vaccine. In the journal Animal in 2013, the New Zealand team reported finding genetic sequences in methanogens that are attractive targets for a vaccine. They’ve also developed a vaccine injection that produces methanogen antibodies in saliva, which would then travel into the rumen. This is one key to delivery, since an average cow produces 100 to 150 liters of spit a day to aid in digestion. Further experiments would have to demonstrate that lowering methanogens won’t affect the animal’s overall health. “The concern is that removing methanogens from the rumen may allow hydrogen to accumulate,” Aspin says. However, “in the limited studies that have been done to date, it doesn’t appear that this is the case.” Sidestepping digestion altogether, some researchers are focusing on breeding a cleaner cow. In Ireland, Ferris and his colleagues experiment with livestock management. Part of the idea is to lengthen the life span of any given animal. “It takes over two years from when a calf is born until she produces her first liter of milk,” he says. If a cow lives longer, her lifetime methane production is spread out over more liters of milk. Also, a farmer does not have to replace as many members of the herd with young, all-methane, no-milk youngsters. In a paper published last year in the Journal of Dairy Science, his research team reported that Norwegian breeds had greater longevity than Holsteins, which make up more than 80 percent of U.S. dairy cows. At the Lacombe Research Centre in the Canadian province of Alberta, researchers collect cow burps when the animals eat from a specially designed fume hood made by C-Lock, Inc. The scientists are breeding animals that naturally produce lower amounts of methane (CH ). Researchers in Alberta are developing lines of cattle that produce less methane because they are born that way. “If you use a feed additive, you’ve got to add it all the time,” says John Basarab, a research scientist for beef cattle production and genetics at Alberta Agriculture and Forestry. But a naturally more efficient cow can get by on less feed for the same growth. Over the last two decades, Basarab and his research team have measured about 5,000 cattle for feed efficiency, and report that old-fashioned selective breeding can produce animals that release up to 25 percent less methane. “In every breed there are animals that are efficient, or inefficient,” he says. The researchers began the research not with methane in mind, but with the idea that animals that extract the most calories from their feed will ultimately be more economical. “Essentially there are animals that eat less for the same amount of growth,” Basarab says. Approaching the methane issue through genetics is slow (the gestation period for a cow is about 280 days), he concedes, but it also has the advantage of being “cumulative and permanent.” He and others say the day may come for cows — just as it did for cars — when governments require certain limits on emissions. And just as organic foods have risen in popularity, consumers may start demanding low-methane products. More and more consumers want to know where their food comes from and whether it’s being produced in a sustainable way, Basarab says. “If you don’t take care of these things, the public might just say that’s a bad way of producing food and we’re not going to buy it.” Making the most of manure The average dairy cow generates about 45 kilograms of manure daily. Next to the animal’s burps, its droppings are a substantial source of methane : Manure accounts for 10 percent of U.S. methane emissions. (For all their gassiness, farts release just a tiny fraction of a cow’s methane.) Much of the focus of the U.S. government’s methane-tackling “Biogas Opportunities Roadmap” was on cow patties. Unlike burps that waft into the air, the methane from manure can be captured by devices called digesters. The airtight devices use the methane generated by the methanogens in manure, which thrive in oxygen-poor environments, to produce energy. The output — either fuel or electricity — powers farm operations or is sold. Digesters are popular at landfills — including one that collects waste at Disney World in Florida — but they are rare in agriculture. Just 239 manure digesters are in operation on U.S. farms (of which there are just over 2 million), according to the Environmental Protection Agency. Yet they generate enough electricity to power the equivalent of about 70,000 homes. — Laura Beil This story appears in the November 28, 2015, Science News with the headline, "Greener cows: Research rounds up less burpy bovines." Editor's note: On November 20, 2015, a clarification was added to the caption for the illustration "As fumes flow" and the credit was corrected.
PubMed | Chinook Contract Research, Alberta Veterinary Laboratories, Alberta Agriculture and Forestry and Alberta Horse Industry Association
Type: Journal Article | Journal: BMC veterinary research | Year: 2016
Castration is one of the most common procedures performed on beef and dairy cattle. The objective of the study was to determine the efficacy of meloxicam oral suspension in reducing pain and inflammation in calves following band or surgical castration.Two identical trials with the exception of the method of castration (Band Castration Study 1 and Surgical Castration Study 2) were conducted. Sixty (60) healthy Holstein calves 4 to 5months of age (138-202 Kg) were used. Animals received either Meloxicam Oral Suspension at a dose of 1mg/kg BW (n=15 Study 1 and 15 Study 2) or Saline (n=15 Study 1 and 15 Study 2) 2h before castration. Physiological (Heart Rate, Plasma Cortisol and Plasma Substance P) and Behavioral (Visual Analog Scale (VAS), Accelerometers and tail Pedometers) evaluations were conducted before (day -1) and after Castration (Day 0, 1, 2, 3). Inflammation was evaluated daily by providing an individual animal score (Study1) or with a measurement of scrotal thickness (Study 2).Heart rates were significantly greater in control animals following band and surgical castration. Plasma cortisol and substance P were significantly reduced in animals receiving Meloxicam Oral Suspension. Control animals had significantly greater VAS scores. Accelerometers showed that meloxicam treated animals had a significantly greater motion index and number of steps as well as less % time lying and number of lying bouts. The scrotal inflammation (based on scrotal swelling) was significantly decreased in the meloxicam treated animals compared to the control animals on day 1, day 2 and 3.Meloxicam Oral Suspension was able to significantly reduce the display of painful behaviors and physiological responses to pain in band castrated and surgical castrated calves for up to 72h following a single oral treatment of 1mg/kg body weight. Meloxicam Oral Suspension was able to significantly reduce scrotal inflammation in band castrated and surgical castrated calves.
Li C.,Natural Resources Canada |
Barclay H.,Victoria |
Huang S.,Alberta Agriculture and Forestry |
Sidders D.,Natural Resources Canada
Landscape Ecology | Year: 2016
Context: A challenging issue in landscape ecology is the evaluation of changes in a forest landscape following a disturbance. This evaluation usually entails examining changes in the forest inventory, which represents the best information available for a given forest region. Objectives: Our aim was to extend existing methods used to evaluate forest inventory to include additional variables, such as value-based forest product options, wood fibre attributes, and ecosystem services. Inclusion of such variables in forest inventory evaluations would allow research results to be presented from an economic perspective, which is often required for policy development and forest management decision-making. Methods: We developed a value-based framework to evaluate forest inventory and implemented it in the wood fibre value simulation model. We then used a local data set from Manitoba, Canada, to show how the model can be applied to the mapping of new inventory layers to facilitate the evaluation of landscape changes. Results: Five new inventory layers are mapped including bioenergy and heating value that can be directly used for evaluating landscape changes, and wood density, fibre length, and pulp yield, which can be combined with total wood volume to derive new variables or indices to express changes in landscape conditions. Conclusions: Our model can contribute to the assessment of landscape changes by indicating the values a forest can have when it is used for different conservation or utilization purposes. The model can also support improved decision-making with respect to the management of forest resources. © 2016 Her Majesty the Queen in Rights of Canada
PubMed | University of Alberta, Natural Resources Canada and Alberta Agriculture and Forestry
Type: Journal Article | Journal: Ecological applications : a publication of the Ecological Society of America | Year: 2016
Most species that are negatively impacted when their densities are low aggregate to minimize this effect. Aggregation has the potential to change how Allee effects are expressed at the population level. We studied the interplay between aggregation and Allee effects in the mountain pine beetle (Dendroctonus ponderosae Hopkins), an irruptive bark beetle that aggregates to overcome tree defenses. By cooperating to surpass a critical number of attacks per tree, the mountain pine beetle is able to breach host defenses, oviposit, and reproduce. Mountain pine beetles and Hymenopteran parasitoids share some biological features, the most notable of which is obligatory host death as a consequence of parasitoid attack and development. We developed spatiotemporal models of mountain pine beetle dynamics that were based on the Nicholson-Bailey framework but which featured beetle aggregation and a tree-level attack threshold. By fitting our models to data from a local mountain pine beetle outbreak, we demonstrate that due to aggregation, attack thresholds at the tree level can be overcome by a surprisingly low ratio of beetles per susceptible tree at the stand level. This results confirms the importance of considering aggregation in models of organisms that are subject to strong Allee effects.
Swallow B.M.,University of Alberta |
Goddard T.W.,Alberta Agriculture and Forestry
International Journal of Climate Change Strategies and Management | Year: 2016
Purpose – This paper aims to track the development of climate policy in the province of Alberta, Canada, particularly the province’s unique greenhouse gas emission offset mechanism. The analysis shows how the policy has influenced, and been influenced by, policy processes at the national and international levels. Design/methodology/approach – The paper begins with an analytical framework that recognizes different types of influence between international, national and provincial climate policy processes. That framework is used to structure a review of four historical periods of climate policy change: prior to 1992, 1992 to 2002, 2002 to 2012 and between 2012 and mid-2015. Findings – The analysis illustrates the interplay between the Alberta approach to climate policy and the international and national policy contexts. A period of intense policy conflict between Canada’s federal and provincial governments led to a situation in which the Alberta Government sought to lead rather than follow national policy. Subsequent periods have seen the Canadian national government oscillate between following the lead of Alberta or the USA. Research limitations/implications – Rather than national and international policies simply setting the context for Alberta’s policy, the paper identifies multiple flows of influence between the three levels of governance. The results illustrate the need to consider forward and backward flows of influence between the different levels of government that set climate change policies. Elements of several models of policy change are supported. Practical implications – The Alberta climate mitigation policy has many elements that can be effective in reducing carbon emissions in a way that is both flexible and predictable. These elements are of interest to other jurisdictions. Other elements of the current policy, however, limit its effectiveness in reducing emissions. More concerted policy action is needed to mitigate carbon emissions in Alberta for Canada to meet its agreed targets. Originality/value – No other paper has tracked the historical evolution of climate policy at the provincial/state level in a way that clarifies the forward and backward linkages with national and international policy. © Emerald Group Publishing Limited.
Mezbahuddin M.,Alberta Agriculture and Forestry |
Mezbahuddin M.,University of Alberta |
Grant R.F.,University of Alberta |
Hirano T.,Hokkaido University
Journal of Geophysical Research G: Biogeosciences | Year: 2015
Soil carbon stocks in tropical peatlands have declined recently from water table depth (WTD) drawdown caused by increased frequency and intensity of climate extremes like El Niño and by artificial drainage. Restoration of these carbon stocks under these climatic and anthropogenic disturbances requires improved predictive capacity for hydrological feedbacks to ecological processes. Process-based modeling of tropical peatland ecohydrology could provide us with such capacity, but such modeling has thus far been limited. We aimed at using basic processes for water and O2 transport and their effects on ecosystem water, carbon, and nitrogen cycling to model seasonal and interannual variations of WTD and surface energy exchange. We tested these processes in a process-based model ecosys in a drained tropical Indonesian peatland from an El Niño year 2002 to a wetter year 2005. WTD was modeled from hydraulically driven water transfers controlled vertically by precipitation versus evapotranspiration (ET) and laterally by discharge versus recharge to or from an external reference WTD. These transfers caused WTD drawdown and soil drying to be modeled during dry seasons, which reduced ET and increased Bowen ratio by lowering stomatal conductance. More pronounced dry seasons in drier years 2002-2004 versus wetter year 2005 caused deeper WTD, more intense peat drying, and greater plant water stress. These modeled trends were well corroborated by site measurements as apparent in regression statistics of modeled versus observed WTD (R2 > 0.8), latent heat (R2 > 0.8), and sensible heat (R2 > 0.7) fluxes. Insights gained from this modeling would aid in predicting the fate of tropical peatlands under future drier climates. Key Points Ecosys modeled tropical peatland WTD by a vertical-lateral hydraulic scheme Deeper WTD caused peat drying and reduced stomatal conductance in dry seasons Stomatal limitation to transpiration was stronger in drier dry seasons ©2015. American Geophysical Union. All Rights Reserved.
PubMed | University of Alberta, Hubei Engineering University and Alberta Agriculture and Forestry
Type: | Journal: Food microbiology | Year: 2016
The pressure resistance of Shiga-toxin producing Escherichia coli (STEC) depends on food matrix. This study compared the resistance of two five-strain E.coli cocktails, as well as the pressure resistant strain E.coli AW1.7, to hydrostatic pressure application in bruschetta, tzatziki, yoghurt and ground beef at 600MPa, 20C for 3min and during post-pressure survival at 4C. Pressure reduced STEC in plant and dairy products by more than 5 logs (cfu/ml) but not in ground beef. The pH affected the resistance of STEC to pressure as well as the post-pressure survival. E.coli with food constituents including calcium, magnesium, glutamate, caffeic acid and acetic acid were treated at 600MPa, 20C. All compounds exhibited a protective effect on E.coli. The antimicrobial compounds ethanol and phenylethanol enhanced the inactivation by pressure. Calcium and magnesium also performed protective effects on E.coli during storage. Glutamate, glutamine or glutathione did not significantly influence the post-pressure survival over 12 days. Preliminary investigation on cell membrane was further performed through the use of fluorescence probe 1-N-phenylnaphthylamine. Pressure effectively permeabilised cell membrane, whereas calcium showed no effects on membrane permeabilisation.
PubMed | Alberta Agriculture and Forestry
Type: Journal Article | Journal: MicrobiologyOpen | Year: 2016
Clustered regularly interspaced short palindromic repeats (CRISPRs) are part of an acquired bacterial immune system that functions as a barrier to exogenous genetic elements. Since naturalized Escherichia coli are likely to encounter different genetic elements in aquatic environments compared to enteric strains, we hypothesized that such differences would be reflected within the hypervariable CRISPR alleles of these two populations. Comparison of CRISPR1 alleles from naturalized and fecal phylogroup B1 E. coli strains revealed that the alleles could be categorized into four major distinct groups (designated G6-G9), and all four allele groups were found among naturalized strains and fecal strains. The distribution of CRIPSR G6 and G8 alleles was similar among strains of both ecotypes, while naturalized strains tended to have CRISPR G7 alleles rather than G9 alleles. Since CRISPR G7 alleles were not specific to naturalized strains, they, however, would not be useful as a marker for identifying naturalized strains. Notably, CRISPR alleles from naturalized and fecal strains also had similar spacer repertoires. This indicates a shared history of encounter with mobile genetic elements and suggests that the two populations were derived from common ancestors.