Summary of Contemporary Research on the Use of Chemical Dispersants for Deep-Sea Oil Spills

Mitigation options for deep-sea oil spills are indeed few. In the open ocean, far from land, booming, burning, and mechanical pickup of oil at the sea surface may be of limited value due to wave and wind conditions. The use of chemicals to disperse oil into smaller droplets is predicated on the assumptions that smaller droplets are more easily dissolved into surrounding waters and that smaller droplets are degraded by bacterial action more rapidly than are larger droplets. During the Deepwater Horizon accident, a novel use of dispersants injected directly into the subsurface source of the blowout was undertaken to treat the oil prior to surfacing. The presence of subsurface “plumes” of small droplets and dissolved oil observed during DWH raised the issue of active measures to sequester oil in the subsurface vs. allowing it to surface. Reducing the concentration of volatile organic compounds surfacing near workers was also a stated objective of subsurface dispersant injection (SSDI) application. Aquatic toxicity testing has evolved significantly from a sole focus on short-term mortality to evaluate a variety of sublethal physiological, genotoxic, and immunogenic impacts affecting animal health and fitness of exposed populations. In this chapter we consider a number of pressing – and heretofore unresolved – issues surrounding the use of dispersants as an oil spill mitigation tool. Further, we advocate continued, targeted research to help resolve ongoing controversies regarding dispersant use

The Role of Alternative Sigma Factors in Pathogen Virulence

Alternative sigma factors enable bacteria to change the promoter specificity of the core RNA polymerase to enable the expression of genes that give them advantages in particular situations. The number of alternative sigma factors that bacteria produce varies greatly. Some bacteria, particularly those that reside in the soil have genes for multiple sigma factors. The soil living gram positive bacteria Sorangium cellulosum currently holds the record for the number of sigma factor genes at 109. Alternative sigma factors play important roles in the life cycle of many foodborne bacterial pathogens. In this review we will discuss: the structure and function of alternative sigma factors; the different families of alternative sigma factors; their regulation; the role of particular alternative sigma factors and the genes they control in the biology (particularly pathogenesis) of foodborne bacterial pathogens