Kevin A. Hughes

Biofilm susceptibility to bacteriophage attack: the role of phage-borne polysaccharide depolymerase

Biofilm bacteria Enterobacter agglomerans 53b and Serratia marcescens Serr were isolated from a food processing factory. A bacteriophage (SF153b), which could infect and lyse strain 53b, was isolated from sewage. This has been shown to possess a polysaccharide depolymerase enzyme specific for the exopolysaccharide (EPS) of strain 53b. Using batch culture and chemostat-linked Modified Robbins Device systems it was observed that SF153b could degrade the EPS of a mono-species biofilm (strain 53b) and infect the cells. The disruption of the biofilm by phage was a combination of EPS degradation by the depolymerase and infection and subsequent cell lysis by the phage. Strain Serr biofilms were not susceptible to the phage and the biofilm EPS was not degraded by the phage glycanase, with the result that the biofilm was unaffected by the addition of SF153b phage. Scanning electron microscopy confirmed that specific phage could extensively degrade susceptible biofilms and continue to infect biofilm bacteria whilst EPS degradation was occurring.

Impacts of local human activities on the Antarctic environment.

Abstract We review the scientific literature, especially from the past decade, on the impacts of human activities on the Antarctic environment. A range of impacts has been identified at a variety of spatial and temporal scales. Chemical contamination and sewage disposal on the continent have been found to be long-lived. Contemporary sewage management practices at many coastal stations are insufficient to prevent local contamination but no introduction of non-indigenous organisms through this route has yet been demonstrated. Human activities, particularly construction and transport, have led to disturbances of flora and fauna. A small number of non-indigenous plant and animal species has become established, mostly on the northern Antarctic Peninsula and southern archipelagos of the Scotia Arc. There is little indication of recovery of overexploited fish stocks, and ramifications of fishing activity on bycatch species and the ecosystem could also be far-reaching. The Antarctic Treaty System and its instruments, in particular the Convention for the Conservation of Antarctic Marine Living Resources and the Environmental Protocol, provide a framework within which management of human activities take place. In the face of the continuing expansion of human activities in Antarctica, a more effective implementation of a wide range of measures is essential, in order to ensure comprehensive protection of the Antarctic environment, including its intrinsic, wilderness and scientific values which remains a fundamental principle of the Antarctic Treaty System. These measures include effective environmental impact assessments, long-term monitoring, mitigation measures for non-indigenous species, ecosystem-based management of living resources, and increased regulation of National Antarctic Programmes and tourism activities.

The interaction of phage and biofilms.

Biofilms present complex assemblies of micro-organisms attached to surfaces. they are dynamic structures in which various metabolic activities and interactions between the component cells occur. When phage come in contact with biofilms, further interactions occur dependent on the susceptibility of the biofilm bacteria to phage and to the availability of receptor sites. If the phage also possess polysaccharide-degrading enzymes, or if considerable cell lysis is effected by the phage, the integrity of the biofilm may rapidly be destroyed. Alternatively, coexistence between phage and host bacteria within the biofilm may develop. Although phage have been proposed as a means of destroying or controlling biofilms, the technology for this has not yet been successfully developed.

Continent-wide risk assessment for the establishment of nonindigenous species in Antarctica

Invasive alien species are among the primary causes of biodiversity change globally, with the risks thereof broadly understood for most regions of the world. They are similarly thought to be among the most significant conservation threats to Antarctica, especially as climate change proceeds in the region. However, no comprehensive, continent-wide evaluation of the risks to Antarctica posed by such species has been undertaken. Here we do so by sampling, identifying, and mapping the vascular plant propagules carried by all categories of visitors to Antarctica during the International Polar Years first season (2007–2008) and assessing propagule establishment likelihood based on their identity and origins and on spatial variation in Antarcticas climate. For an evaluation of the situation in 2100, we use modeled climates based on the Intergovernmental Panel on Climate Changes Special Report on Emissions Scenarios Scenario A1B [Nakićenović N, Swart R, eds (2000) Special Report on Emissions Scenarios: A Special Report of Working Group III of the Intergovernmental Panel on Climate Change (Cambridge University Press, Cambridge, UK)]. Visitors carrying seeds average 9.5 seeds per person, although as vectors, scientists carry greater propagule loads than tourists. Annual tourist numbers (∼33,054) are higher than those of scientists (∼7,085), thus tempering these differences in propagule load. Alien species establishment is currently most likely for the Western Antarctic Peninsula. Recent founder populations of several alien species in this area corroborate these findings. With climate change, risks will grow in the Antarctic Peninsula, Ross Sea, and East Antarctic coastal regions. Our evidence-based assessment demonstrates which parts of Antarctica are at growing risk from alien species that may become invasive and provides the means to mitigate this threat now and into the future as the continents climate changes.

Microorganisms in the atmosphere over Antarctica

Antarctic microbial biodiversity is the result of a balance between evolution, extinction and colonization, and so it is not possible to gain a full understanding of the microbial biodiversity of a location, its biogeography, stability or evolutionary relationships without some understanding of the input of new biodiversity from the aerial environment. In addition, it is important to know whether the microorganisms already present are transient or resident - this is particularly true for the Antarctic environment, as selective pressures for survival in the air are similar to those that make microorganisms suitable for Antarctic colonization. The source of potential airborne colonists is widespread, as they may originate from plant surfaces, animals, water surfaces or soils and even from bacteria replicating within the clouds. On a global scale, transport of air masses from the well-mixed boundary layer to high-altitude sites has frequently been observed, particularly in the warm season, and these air masses contain microorganisms. Indeed, it has become evident that much of the microbial life within remote environments is transported by air currents. In this review, we examine the behaviour of microorganisms in the Antarctic aerial environment and the extent to which these microorganisms might influence Antarctic microbial biodiversity.

Solar UV-B Radiation Inhibits the Growth of Antarctic Terrestrial Fungi

ABSTRACT We tested the effects of solar radiation, and UV-B in particular, on the growth of Antarctic terrestrial fungi. The growth responses to solar radiation of five fungi, Geomyces pannorum, Phoma herbarum, Pythium sp., Verticillium sp., and Mortierella parvispora, each isolated from Antarctic terrestrial habitats, were examined on an agar medium in the natural Antarctic environment. A 3-h exposure to solar radiation of >287 nm reduced the hyphal extension rates of all species relative to controls kept in the dark. Pythium sp. cultures exposed to solar radiation for 1.5 h on five consecutive days were most sensitive to radiation of >287 nm, but radiation of >313 nm also inhibited growth to a lesser extent. Radiation of >400 nm had no effect on hyphal growth relative to controls kept in the dark. Short-wave solar UV-B radiation of between 287 and 305 nm inhibited the growth of Pythium sp. hyphae on and below the surface of the agar medium after 24 h, but radiation of ≥345 nm only reduced the growth of surface hyphae. Similar detrimental effects of UV-B on surface and, to a lesser extent, submerged hyphae of all five fungi were shown in the laboratory by using artificial UV-B from fluorescent lamps. A comparison of growth responses to solar radiation and temperature showed that the species that were most resistant to UV radiation grew fastest at higher temperatures. These data suggest that solar UV-B reduces the growth of fungi on the soil surface in the Antarctic terrestrial environment.

Challenges to the Future Conservation of the Antarctic

Changing environments and resource demands present challenges to Antarctic conservation. The Antarctic Treaty System, acknowledged as a successful model of cooperative regulation of one of the globes largest commons (1), is under substantial pressure. Concerns have been raised about increased stress on Antarctic systems from global environmental change and growing interest in the regions resources (2, 3). Although policy-makers may recognize these challenges, failure to respond in a timely way can have substantial negative consequences. We provide a horizon scan, a systematic means for identifying emerging trends and assisting decision-makers in identifying policies that address future challenges (2, 3). Previous analyses of conservation threats in the Antarctic have been restricted to matters for which available evidence is compelling (4). We reconsider these concerns because they might escalate quickly, judging from recent rapid environmental change in parts of Antarctica and increasing human interest in the region (see the map). We then focus on a more distant time horizon.

Anthropogenic impacts on marine ecosystems in Antarctica

Antarctica is the most isolated continent on Earth, but it has not escaped the negative impacts of human activity. The unique marine ecosystems of Antarctica and their endemic faunas are affected on local and regional scales by overharvesting, pollution, and the introduction of alien species. Global climate change is also having deleterious impacts: rising sea temperatures and ocean acidification already threaten benthic and pelagic food webs. The Antarctic Treaty System can address local‐ to regional‐scale impacts, but it does not have purview over the global problems that impinge on Antarctica, such as emissions of greenhouse gases. Failure to address human impacts simultaneously at all scales will lead to the degradation of Antarctic marine ecosystems and the homogenization of their composition, structure, and processes with marine ecosystems elsewhere.

Determining the native/non-native status of newly discovered terrestrial and freshwater species in Antarctica - current knowledge, methodology and management action.

Continental Antarctic terrestrial and freshwater environments currently have few established non-native species compared to the sub-Antarctic islands and other terrestrial ecosystems on Earth. This is due to a unique combination of factors including Antarcticas remoteness, harsh climate, physical geography and brief history of human activity. However, recent increases in national operator and tourism activities increase the risk of non-native propagules reaching Antarctica, while climate change may make successful establishment more likely. The frequency and probability of human-assisted transfer mechanisms appear to far outweigh those of natural propagule introductions by wind, water, birds and marine mammals. A dilemma for scientists and environmental managers, which is exacerbated by a poor baseline knowledge of Antarctic biodiversity, is how to determine the native/non-native status of a newly discovered species which could be (a) a previously undiscovered long-term native species, (b) a recent natural colonist or (c) a human-mediated introduction. A correct diagnosis is crucial as the Protocol on Environmental Protection to the Antarctic Treaty dictates dramatically different management responses depending on native/non-native status: native species and recent natural colonists should be protected and conserved, while non-native introductions should be eradicated or controlled. We review current knowledge on how available evidence should be used to differentiate between native and non-native species, and discuss and recommend issues that should be considered by scientists and managers upon discovery of a species apparently new to the Antarctic region.

Biological invasions in terrestrial Antarctica: what is the current status and can we respond?

Until recently the Antarctic continent and Peninsula have been little impacted by non-native species, compared to other regions of the Earth. However, reports of species introductions are increasing as awareness of biological invasions as a major conservation threat, within the context of increased human activities and climate change scenarios, has grown within the Antarctic community. Given the recent increase in documented reports, here we provide an up-to-date inventory of known terrestrial non-native species introductions, including those subsequently removed since the 1990s, within the Antarctic Treaty area. This builds on earlier syntheses of records published in the mid-2000s, which focused largely on the sub-Antarctic islands, given the dearth of literature available at that time from the continental and maritime Antarctic regions. Reports of non-native species established in the natural environment (i.e. non-synanthropic) are mainly located within the Antarctic Peninsula region and Scotia Arc, with Deception Island, South Shetland Islands, the most impacted area. Non-native plants have generally been removed from sites of introduction, but no established invertebrates have yet been subject to any eradication attempt, despite a recent increase in reports. Legislation within the Protocol on Environmental Protection to the Antarctic Treaty has not kept pace with environmental best practice, potentially presenting difficulties for the practical aspects of non-native species control and eradication. The success of any eradication attempt may be affected by management practices and the biology of the target species under polar conditions. Practical management action is only likely to succeed with greater co-operation and improved communication and engagement by nations and industries operating in the region.