Natural attenuation of lead by microbial manganese oxides in a karst aquifer.

Lead is a toxic environmental contaminant associated with current and historic mine sites. Here we studied the natural attenuation of Pb in a limestone cave system that receives drainage from the ancient Priddy Mineries, UK. Extensive deposits of manganese oxides were observed to be forming on the cave walls and as coatings in the stream beds. Analysis of these deposits identified them as birnessite (δ-MnO2), with some extremely high concentrations of sorbed Pb (up to 56 wt%) also present. We hypothesised that these cave crusts were actively being formed by microbial Mn(II)-oxidation, and to investigate this the microbial communities were characterised by DNA sequencing, enrichment and isolation experiments. The birnessite deposits contained abundant and diverse prokaryotes and fungi, with ~5% of prokaryotes and ~ 10% of fungi closely related to known heterotrophic Mn(II)-oxidisers. A substantial proportion (up to 17%) of prokaryote sequences were assigned to groups known as autotrophic ammonia and nitrite oxidisers, suggesting that nitrogen cycling may play an important role in contributing energy and carbon to the cave crust microbial communities and consequently the formation of Mn(IV) oxides and Pb attenuation. Enrichment and isolation experiments showed that the birnessite deposits contained Mn(II)-oxidising microorganisms, and two isolates (Streptomyces sp. and Phyllobacterium sp.) could oxidise Mn(II) in the presence of 0.1 mM Pb. Supplying the enrichment cultures with acetate as a source of energy and carbon stimulated Mn(II)-oxidation, but excess organics in the form of glucose generated aqueous Mn(II), likely via microbial Mn(IV)-reduction. In this karst cave, microbial Mn(II)-oxidation contributes to the active sequestration and natural attenuation of Pb from contaminated waters, and therefore may be considered a natural analogue for the design of wastewater remediation systems and for understanding the geochemical controls on karst groundwater quality, a resource relied upon by billions of people across the globe.

An International Collaborative Approach to Developing Training Guidelines for Veterinary Paraprofessionals.

Veterinary paraprofessionals (VPPs) are engaged worldwide in animal health management, disease surveillance and food safety control. In many countries, particularly developing countries, VPPs are critical to national veterinary services provision. Until recently, there were no globally recognized training requirements for VPPs. Recognition of VPPs' qualifications and roles, and requirements for registration, vary greatly between jurisdictions. To address these issues, the World Organisation for Animal Health (OIE) has developed competency and curricular guidelines for VPPs. A collaborative approach was essential to this mission. Extensive consultation with individuals and agencies representing various countries, animal health and veterinary sectors, and forms of expertise, was undertaken. Collaborative methods included the formation of a guidelines development ad hoc group whose diversity reflected project needs, the use of existing OIE Member Country data to understand roles of VPPs globally, conducting stakeholder surveys to collate VPP competency expectations and solicit feedback on draft guidelines, and in-country missions to validate draft curricular models. The initial deliverable from this work was publication of Competency Guidelines for VPPs. This document provides recommendations on the knowledge, skills, attitudes, and aptitudes that could be expected of VPPs following effective training. The companion document, OIE Curricular Guidelines for VPPs, provides recommendations on coursework structure and content to achieve these competencies. These guidelines will assist countries worldwide in more effectively training and qualifying VPPs so that they can contribute positively to the provision of veterinary services. Another potential impact is to catalyze the review of educational and regulatory standards regarding the respective work rights and activities of veterinarians and VPPs.

Perspective on the OIE Veterinary Education Establishment Twinning Programme.

This article introduces the Supplement Issue of the Journal of Veterinary Medical Education (JVME) on the OIE Veterinary Education Establishment Twinning Programme. It provides some background on the origins of the program, information on its implementation, and some of the outcomes and benefits already identified.

A global veterinary medical perspective on the concept of one health: focus on livestock.

While globalization has yielded many benefits for society, it also has created many new challenges, particularly with regard to animal, human, and environmental health. Livestock contribute significantly to the livelihoods of hundreds of millions of people worldwide and global demand for foods of animal origin has been steadily increasing for decades. It is therefore critical to recognize and understand the global dimension of livestock production and its impacts. Despite the clear benefits of livestock for humans, some livestock production practices are associated with certain forms of environmental degradation, and trade in livestock and livestock products can contribute to the emergence and spread of new animal and zoonotic diseases. This article provides a review of the major global trends affecting livestock production and trade, related implications for human, animal, and environmental health, and reasons why veterinarians should embrace a One Health approach in dealing with disease problems in this era of globalization.

Ion association in concentrated NaCI brines from ambient to supercritical conditions: results from classical molecular dynamics simulations.

Highly concentrated NaCl brines are important geothermal fluids; chloride complexation of metals in such brines increases the solubility of minerals and plays a fundamental role in the genesis of hydrothermal ore deposits. There is experimental evidence that the molecular nature of the NaCl-water system changes over the pressure-temperature range of the Earth's crust. A transition of concentrated NaCl-H2O brines to a "hydrous molten salt" at high P and T has been argued to stabilize an aqueous fluid phase in the deep crust. In this work, we have done molecular dynamic simulations using classical potentials to determine the nature of concentrated (0.5-16 m) NaCl-water mixtures under ambient (25°C, 1 bar), hydrothermal (325°C, 1 kbar) and deep crustal (625°C, 15 kbar) conditions. We used the well-established SPCE model for water together with the Smith and Dang Lennard-Jones potentials for the ions (J. Chem. Phys., 1994, 100, 3757). With increasing temperature at 1 kbar, the dielectric constant of water decreases to give extensive ion-association and the formation of polyatomic (Na n Cl m ) n-m clusters in addition to simple NaCl ion pairs. Large polyatomic (Na n Cl m ) n-m clusters resemble what would be expected in a hydrous NaCl melt in which water and NaCl were completely miscible. Although ion association decreases with pressure, temperatures of 625°C are not enough to overcome pressures of 15 kbar; consequently, there is still enhanced Na-Cl association in brines under deep crustal conditions.