Simulation of Deepwater Horizon oil plume reveals substrate specialization within a complex community of hydrocarbon degraders.

The Deepwater Horizon (DWH) accident released an estimated 4.1 million barrels of oil and 1010 mol of natural gas into the Gulf of Mexico, forming deep-sea plumes of dispersed oil droplets and dissolved gases that were largely degraded by bacteria. During the course of this 3-mo disaster a series of different bacterial taxa were enriched in succession within deep plumes, but the metabolic capabilities of the different populations that controlled degradation rates of crude oil components are poorly understood. We experimentally reproduced dispersed plumes of fine oil droplets in Gulf of Mexico seawater and successfully replicated the enrichment and succession of the principal oil-degrading bacteria observed during the DWH event. We recovered near-complete genomes, whose phylogeny matched those of the principal biodegrading taxa observed in the field, including the DWH Oceanospirillales (now identified as a Bermanella species), multiple species of Colwellia, Cycloclasticus, and other members of Gammaproteobacteria, Flavobacteria, and Rhodobacteria. Metabolic pathway analysis, combined with hydrocarbon compositional analysis and species abundance data, revealed substrate specialization that explained the successional pattern of oil-degrading bacteria. The fastest-growing bacteria used short-chain alkanes. The analyses also uncovered potential cooperative and competitive relationships, even among close relatives. We conclude that patterns of microbial succession following deep ocean hydrocarbon blowouts are predictable and primarily driven by the availability of liquid petroleum hydrocarbons rather than natural gases.

Microbial communities related to biodegradation of dispersed Macondo oil at low seawater temperature with Norwegian coastal seawater.

The Deepwater Horizon (DWH) accident in 2010 created a deepwater plume of small oil droplets from a deepwater well in the Mississippi Canyon lease block 252 ('Macondo oil'). A novel laboratory system was used in the current study to investigate biodegradation of Macondo oil dispersions (10 µm or 30 µm median droplet sizes) at low oil concentrations (2 mg l(-1)) in coastal Norwegian seawater at a temperature of 4-5°C. Whole metagenome analyses showed that oil biodegradation was associated with the successive increased abundances of Gammaproteobacteria, while Alphaproteobacteria (Pelagibacter) became dominant at the end of the experiment. Colwellia and Oceanospirillales were related to n-alkane biodegradation, while particularly Cycloclasticus and Marinobacter were associated with degradation of aromatic hydrocarbons (HCs). The larger oil droplet dispersions resulted in delayed sequential changes of Oceanospirillales and Cycloclasticus, related with slower degradation of alkanes and aromatic HCs. The bacterial successions associated with oil biodegradation showed both similarities and differences when compared with the results from DWH field samples and laboratory studies performed with deepwater from the Gulf of Mexico.

Oil spill problems and sustainable response strategies through new technologies.

Crude oil and petroleum products are widespread water and soil pollutants resulting from marine and terrestrial spillages. International statistics of oil spill sizes for all incidents indicate that the majority of oil spills are small (less than 7 tonnes). The major accidents that happen in the oil industry contribute only a small fraction of the total oil which enters the environment. However, the nature of accidental releases is that they highly pollute small areas and have the potential to devastate the biota locally. There are several routes by which oil can get back to humans from accidental spills, e.g. through accumulation in fish and shellfish, through consumption of contaminated groundwater. Although advances have been made in the prevention of accidents, this does not apply in all countries, and by the random nature of oil spill events, total prevention is not feasible. Therefore, considerable world-wide effort has gone into strategies for minimising accidental spills and the design of new remedial technologies. This paper summarizes new knowledge as well as research and technology gaps essential for developing appropriate decision-making tools in actual spill scenarios. Since oil exploration is being driven into deeper waters and more remote, fragile environments, the risk of future accidents becomes much higher. The innovative safety and accident prevention approaches summarized in this paper are currently important for a range of stakeholders, including the oil industry, the scientific community and the public. Ultimately an integrated approach to prevention and remediation that accelerates an early warning protocol in the event of a spill would get the most appropriate technology selected and implemented as early as possible - the first few hours after a spill are crucial to the outcome of the remedial effort. A particular focus is made on bioremediation as environmentally harmless, cost-effective and relatively inexpensive technology. Greater penetration into the remedial technologies market depends on the harmonization of environment legislation and the application of modern laboratory techniques, e.g. ecogenomics, to improve the predictability of bioremediation.

Oil Biodegradation and Oil-Degrading Microbial Populations in Marsh Sediments Impacted by Oil from the Deepwater Horizon Well Blowout.

To study hydrocarbon biodegradation in marsh sediments impacted by Macondo oil from the Deepwater Horizon well blowout, we collected sediment cores 18-36 months after the accident at the marshes in Bay Jimmy (Upper Barataria Bay), Louisiana, United States. The highest concentrations of oil were found in the top 2 cm of sediment nearest the waterline at the shorelines known to have been heavily oiled. Although petroleum hydrocarbons were detectable, Macondo oil could not be identified below 8 cm in 19 of the 20 surveyed sites. At the one site where oil was detected below 8 cm, concentrations were low. Residual Macondo oil was already highly weathered at the start of the study, and the concentrations of individual saturated hydrocarbons and polycyclic aromatic hydrocarbons continued to decrease over the course of the study due to biodegradation. Desulfococcus oleovorans, Marinobacter hydrocarbonoclasticus, Mycobacterium vanbaalenii, and related mycobacteria were the most abundant oil-degrading microorganisms detected in the top 2 cm at the oiled sites. Relative populations of these taxa declined as oil concentrations declined. The diversity of the microbial community was low at heavily oiled sites compared to that of the unoiled reference sites. As oil concentrations decreased over time, microbial diversity increased and approached the diversity levels of the reference sites. These trends show that the oil continues to be biodegraded, and microbial diversity continues to increase, indicating ongoing overall ecological recovery.

The Future of One Health.

There are significant opportunities for improving human, animal, and environmental health by adopting a One Health approach. One Health approaches are likely to have a major impact on public health, with a focus on surveillance and upstream interventions that are likely to reap obvious and rapid benefits for the health of human populations. However, despite the obvious benefits, the barriers to achieving a comprehensive One Health approach are formidable given that education, research, diagnostics, surveillance, and funding for human medicine, veterinary medicine, and environmental health often exist as separate silos with limited exchange. These barriers must be overcome if the benefits of One Health are to be realized.

One Health: its origins and future.

One Health is an emerging concept that aims to bring together human, animal, and environmental health. Achieving harmonized approaches for disease detection and prevention is difficult because traditional boundaries of medical and veterinary practice must be crossed. In the nineteenth and early twentieth centuries, this was not the case-then researchers like Louis Pasteur and Robert Koch and physicians like William Osler and Rudolph Virchow crossed the boundaries between animal and human health. More recently, Calvin Schwabe revived the concept of One Medicine. This was critical for the advancement of the field of epidemiology, especially as applied to zoonotic diseases. The future of One Health is at a crossroad with the need to more clearly define its boundaries and demonstrate its benefits. Interestingly, the greatest acceptance of One Health is seen in the developing world where it is having significant impacts on control of infectious diseases.

Oil biodegradation and bioremediation: a tale of the two worst spills in U.S. history.

The devastating environmental impacts of the Exxon Valdez spill in 1989 and its media notoriety made it a frequent comparison to the BP Deepwater Horizon spill in the popular press in 2010, even though the nature of the two spills and the environments impacted were vastly different. Fortunately, unlike higher organisms that are adversely impacted by oil spills, microorganisms are able to consume petroleum hydrocarbons. These oil degrading indigenous microorganisms played a significant role in reducing the overall environmental impact of both the Exxon Valdez and BP Deepwater Horizon oil spills.

Protection of Salmonella by ampicillin-resistant Escherichia coli in the presence of otherwise lethal drug concentrations.

Microbial systems have become the preferred testing grounds for experimental work on the evolution of traits that benefit other group members. This work, based on conceptual and theoretical models of frequency-dependent selection within populations, has proven fruitful in terms of understanding the dynamics of group beneficial or 'public goods' traits within species. Here, we expand the scope of microbial work on the evolution of group-beneficial traits to the case of multi-species communities, particularly those that affect human health. We examined whether beta-lactamase-producing Escherichia coli could protect ampicillin-sensitive cohorts of other species, particularly species that could cause human disease. Both beta-lactamase-secreting E. coli and, surprisingly, those engineered to retain it, allowed for survival of a large number of ampicillin-sensitive cohorts of Salmonella enterica serovar Typhimurium, including both laboratory and clinical isolates. The Salmonella survivors, however, remained sensitive to ampicillin when re-plated onto solid medium and there was no evidence of gene transfer. Salmonella survival did not even require direct physical contact with the resistant E. coli. The observed phenomenon appears to involve increased release of beta-lactamase from the E. coli when present with S. enterica. Significantly, these findings imply that resistant E. coli, that are not themselves pathogenic, may be exploited, even when they are normally selfish with respect to other E. coli. Thus, Salmonella can gain protection against antibiotics from E. coli without gene transfer, a phenomenon not previously known. As a consequence, antibiotic-resistant E. coli can play a decisive role in the survival of a species that causes disease and may thereby interfere with successful treatment.

Evolution of altruists and cheaters in near-isogenic populations of Escherichia coli.

Emergence of antibiotic-resistant bacteria threatens the continued efficacy of many critical drugs used to treat serious infections. What if such resistant organisms could also act as altruists and "share" their resistance with sensitive cohorts without any actual genetic exchange? We competed resistant strains that differ solely in their ability to secrete a plasmid-encoded beta-lactamase. Sensitive strains were otherwise isogenic with their resistant counterparts and were either plasmid-free or contained a "Dummy" plasmid of roughly the same size as that of the resistance plasmids. Absent antibiotic selection, plasmid-free sensitive strains outperformed the plasmid-bearing strains. In the presence of ampicillin, the outcome depended on whether the resistant strain secreted its beta-lactamase (Altruist) or retained it (Selfish). In the latter case, only resistant cells survived. When beta-lactamase was secreted, some sensitive cohorts were also provided protection, with the largest fitness increase provided to plasmid-free cells. However, some Altruist strains appeared to be at a disadvantage, as a great deal of their enzyme broke off cells. Thus, additional variables must be considered when designing microbial competition experiments.

Responsible conduct by life scientists in an age of terrorism.

The potential for dual use of research in the life sciences to be misused for harm raises a range of problems for the scientific community and policy makers. Various legal and ethical strategies are being implemented to reduce the threat of the misuse of research and knowledge in the life sciences by establishing a culture of responsible conduct.

Cheating on the edge.

We present the results of an individual agent-based model of antibiotic resistance in bacteria. Our model examines antibiotic resistance when two strategies exist: "producers"--who secrete a substance that breaks down antibiotics--and nonproducers ("cheats") who do not secrete, or carry the machinery associated with secretion. The model allows for populations of up to 10,000, in which bacteria are affected by their nearest neighbors, and we assume cheaters die when there are no producers in their neighborhood. Each of 10,000 slots on our grid (a torus) could be occupied by a producer or a nonproducer, or could (temporarily) be unoccupied. The most surprising and dramatic result we uncovered is that when producers and nonproducers coexist at equilibrium, nonproducers are almost always found on the edges of clusters of producers.

Distribution and weathering of crude oil residues on shorelines 18 years after the Exxon Valdez spill.

In 2007, a systematic study was conducted to evaluate the form and location of residues of oil buried on Prince William Sound (PWS) shorelines, 18 years after the 1989 Exxon Valdez Oil Spill (EVOS). We took 678 sediment samples from 22 sites that were most heavily oiled in 1989 and known to contain the heaviest subsurface oil (SSO) deposits based on multiple studies conducted since 2001. An additional 66 samples were taken from two sites, both heavily oiled in 1989 and known to be active otter foraging sites. All samples were analyzed for total extractable hydrocarbons (TEH), and 25% were also analyzed for saturated and aromatic hydrocarbon weathering parameters. Over 90% of the samples from all sites contained light or no SSO at all. Of samples containing SSO, 81% showed total polycyclic aromatic hydrocarbon (TPAH) losses greater than 70%, relative to cargo oil, with most having >80% loss. Samples with SSO were observed in isolated patches sequestered by surface boulder and cobble armoring. Samples showing lowest TPAH loss correlated strongly with higher elevations in the intertidal zones. Of the 17 atypical, less-weathered samples having less than 70% loss of TPAH (>30% remaining), only two were found sequestered in the lower intertidal zone, both at a single site. Most of the EVOS oil in PWS has been eliminated due to natural weathering. Some isolated SSO residues remain because they are sequestered and only slowly affected by natural weathering processes that normally would bring about their rapid removal. Even where SSO patches remain, most are highly weathered, sporadically distributed at a small number of sites, and widely separated from biologically productive lower intertidal zones where most foraging by wildlife occurs.

The dual-use dilemma for the life sciences: perspectives, conundrums, and global solutions.

The term "dual-use" traditionally has been used to describe technologies that could have both civilian and military usage, but this term has at least three different dimensions that pose a dilemma for modern biology and its possible misuse for hostile purposes: (1) ostensibly civilian facilities that are in fact intended for military or terrorist bioweapons development and production; (2) equipment and agents that could be misappropriated and misused for biological weapons development and production; and (3) the generation and dissemination of scientific knowledge that could be misapplied for biological weapons development and production. These three different aspects of the "dual-use dilemma" are frequently confused--each demands a distinct approach within a "web of prevention" in order to reduce the future risk of bioterrorism and biowarfare. This article discusses the nature of the different perspectives and divergent approaches as a contribution to finding a scientifically acceptable global solution to the problem posed by the dual-use dilemma. We propose that: (1) facilities that are intended for bioweapons development and production should be primarily prevented by a strengthened Biological and Toxin Weapons Convention (BTWC) effectively implemented in all nation states, one that includes provisions for adequate transparency to improve confidence and a mechanism for thorough inspections when there is sufficient cause, and enhanced law enforcement activities involving international cooperation and sharing of critical intelligence information; (2) potentially dual-use equipment and agents should be available to legitimate users for peaceful purposes, but strengthened national biosafety and physical and personnel biosecurity controls in all nations together with effective export controls should be implemented to limit the potential for the misappropriation of such equipment and materials; and (3) information should be openly accessible by the global scientific community, but a culture of responsible conduct involving the breadth of the international life sciences communities should be adopted to protect the ongoing revolution in the life sciences from being hijacked for hostile misuse of the knowledge generated and communicated by life scientists.

Recognizing biothreat diseases: realistic training using standardized patients and patient simulators.

The UofL Center for the Deterrence of Biowarfare and Bioterrorism's (CDBB's) training involving standardized patients, who can make convincingly accurate representations of clinical signs and symptoms, and patient simulators has proven to be an effective means of enhancing bioterrorism preparedness. In addition to providing ready access to formative measures of preparedness, both of these teaching and learning tools also offer the option of summative evaluation of skills and knowledge acquired during training sessions. The use of moulage allows for very realistic representations of cutaneous anthrax and smallpox as well as other conditions such as recluse spider bites and chickenpox with which these biothreat infections can be confused. Exercises and drills expose deficiencies and permit essential reinforcement of skills developed in training. Unannounced exercises are especially useful in assessing public health preparedness.

Biodefense research: an emerging conundrum.

Biodefense research creates a conundrum for the scientific community--what are the permissible limits of biodefense research and how can knowledge in the life sciences be protected against misuse? As biodefense research expands to counter the threat of bioterrorism, so does suspicion and the need for guidance to respond to these concerns.

Globalizing biosecurity.

A harmonized international regime that enhances biosecurity is needed to reduce the risk of bioterrorism. Like other security regimes, this will entail mutually reinforcing strands, which need to include: enactment of legally binding control of access to dangerous pathogens, transparency for sanctioned biodefense programs, technology transfer and assistance to developing countries to jointly advance biosafety and biosecurity, global awareness of the dual-use dilemma and the potential misuse of science by terrorists, and development of a global ethic of compliance. To work, this effort must be undertaken collectively, utilizing the international and regional institutions that already have a role to play in providing safety and security. Most notably, it must grow in a top-down manner from the Biological Weapons Convention accord, in which States Parties have agreed to ban the development of biological weapons, and in a bottom-up manner from the scientific and health communities, which are engaged in the research and public health efforts that must be protected against misuse-especially involving the World Health Organization.