Review Articles in 2007

Acinetobacterstrains have become a cause for concern — particularly among critically ill, hospitalized patients — owing to the spread of multidrug resistance and risk of epidemics. Here, the authors discuss the current knowledge of the genusAcinetobacter, with the emphasis on the clinically most important species, Acinetobacter baumannii.

Almost all bacteria can adapt efficiently to different nutritional environments by using global regulators that link gene expression to the available intracellular pools of a small number of key metabolites. Here, Abraham L. Sonenshein reviews howBacillus subtilisuses global regulators to manage traffic through two metabolic intersections that determine the flow of carbon and nitrogen to and from crucial metabolites.

How is it that biofilms are less susceptible to metal toxicity than exponentially growing planktonic cell populations? Here, Harrison and colleagues propose a multifactorial model of biofilm multimetal resistance and tolerance by which biofilms can withstand metal toxicity by an ongoing process of cellular diversification within the microbial population.

The Sec pathway, which transports proteins across membranes, is ubiquitous and essential for viability in all three domains of life. At the core of the pathway is the translocase, a dynamic nanomachine that catalyses transmembrane crossing. This Review considers the latest data on the structure and function of the bacterial Sec translocase.

Every year there are an estimated 500,000 new cases of visceral leishmaniasis (VL) and more than 50,000 deaths from the disease, a death toll that is surpassed among the parasitic diseases only by malaria. The epidemiology, clinical presentation and pathogenesis of VL are reviewed, along with the current control strategies and research challenges.

The complex life cycle ofMyxococcus xanthusincludes predation, swarming, fruiting-body formation and sporulation. The large genome of this bacterium contains eight chemotaxis gene clusters that define eight two-component chemosensory pathways, most of which have dedicated functions in motility or development.

The long-held belief that bacteria rely solely on homologous recombination for the repair of double-strand breaks was recently overturned by evidence that many bacterial genera contain a system for non-homologous end joining (NHEJ). Biochemical, structural and genetic studies are beginning to define an NHEJ pathway that has distinctive features and enzymatic components.

The deep-sea environment comprises a wealth of distinct ecosystems, such as hydrothermal vents, cold seeps and subsurface habitats. A multitude of bacteria and archaea live in these distant niches, and face challenges for growth at extremes of temperature, pressure and carbon limitation. This Review describes life in the deep-sea biosphere and discusses how microorganisms overcome the scarcity of energy resources, which is relevant to understanding the limitations to, and the diversity of, life on Earth.

In this Review, the authors discuss the benefits of thinking about the ocean in terms of microniches and advocate the study of global processes on a microscale. Farooq Azam and Francesca Malfatti stress the need to study oceanic microbiologyin situand to use this as a unifying basis for modelling the influence of microorganisms on the structure of marine ecosystems. This might lead to new insights into the regulation of primary production and carbon cycling.

David Karl provides a critical review of the exciting new discipline of microbial oceanography by discussing selected key advances. These include probing the metabolic balance in the oceans, the exciting discovery of bacterial proteorhodopsin, establishing a long-term ocean observatory, the unexpected role of marine Archaea, and attempts to understand the result of perturbing nutrient levels in the sea.

In coastal systems mixed metabolic strategies of marine heterotrophic bacteria have implications for how efficiently organic carbon is retained in the marine food web, and how climatically important gases are exchanged between the ocean and the atmosphere. These resourceful heterotrophs use light, either directly or indirectly, to obtain supplemental energy and decrease their reliance on organic matter. This Review highlights these mechanisms and their importance to coastal carbon cycling by marine bacteria.

If stretched end to end, the estimated 10³⁰viruses in the oceans would span farther than the nearest 60 galaxies. This reservoir of genetic and biological diversity continues to yield exciting discoveries and, in this Review, Curtis A. Suttle highlights the areas that are likely to be of greatest interest in the next few years.

Soils are highly complex and challenging environments to study. In this Review, Tony O'Donnell and colleagues call for the development of soil microbiology into a systems science. Imaging and modelling techniques are reviewed that together should enable microbial ecologists to examine the implications of spatio–temporal heterogeneity for the dynamics of microbial communities and their physical environments.

AlthoughCampylobacter jejuni is a common foodborne bacterial pathogen, we know less about its biology and pathogenicity than we do about other less prevalent pathogens. Here, we examine the biological factors of C. jejunithat contribute to colonization and disease in humans and chickens.

Generations of microbiologists have relied on traditional genetic screening techniques to isolate mutants. Nowadays, advances in high-throughput technologies mean that fluorescent assays can be exploited for the rapid isolation of mutants with complex phenotypes. These single-cell techniques, which include flow cytometry and microfluidic applications, and their uses in microbiology, are discussed in this Review.

Although microorganisms have gained notoriety as pathogens, many interactions with microorganisms benefit hosts and can affect development, immunity and nutrition. This Review discusses common features of pathogenic and mutualistic interactions that have arisen from studies withXenorhabdus nematophila, which influences the lives of two different host animals.

Several prions have been identified in fungi, where they behave as non-chromosomal cytoplasmic genetic elements that are transmitted from cell to cell during cell fusion. In this Review, Reed B. Wickner and colleagues take an in-depth look at the biology and structure of fungal prions.

The symbiotic relationship between leguminous plants and rhizobial bacteria is one of the most well-studied microbial symbioses. The availability of genome sequence information for many of the bacterial and plant partners involved has been invaluable and in this article, the authors review the most recent discoveries about the mutual recognition betweenSinorhizobium meliloti and Medicago truncatula.