This Research Topic presents knowledge on transition metal metabolism in various infections from the dual perspective of offender and defender. 1) Host Nutritional Immunity: depriving or poisoning. To date, the implication of divalent metals have been described in two different immune strategies that aim to fight microbial invaders. One consists in depriving microbes of essential divalent metals whereas the other aims at overloading invaders with toxic concentrations of metal. The contributions in this section present, in different situations, various aspects of this metal economy at the host-microbe interface. Two papers deal with metal homeostasis as hosts interact with bacteria. Diaz-Ochoa et al. (2014) review immunological mechanisms to sequester Fe, Mn and Zn in the inflamed gut and strategies of commensals and pathogens to evade mucosal defenses and obtain such nutrients. Lisher & Giedroc (2013) detail chemical and structural mechanisms to capture Mn, an antioxidant used by pathogens to adapt to human hosts, and the impact of Fe and Zn on Mn bioavailability during infections. The most coveted metal, iron is key to nutritional immunity and microbial virulence. Using amoeba as model phagocyte, Bozzaro et al. (2013) present the tug of war between a bacterial predator, sequestering intracellular iron to resist invasion, and pathogens which elude such defense mechanisms. On mammalian defense against intracellular bacteria and protozoan parasites, Silva-Gomes et al. (2013) outline divergent approaches: iron-withholding to prevent microbial replication or iron-based oxidative injury to kill invaders. Host may also target invaders with toxic doses of Cu and Zn, normally kept at low concentrations. Neyrolles et al. (2013) present an opinion article on bacterial Zn and Cu poisoning in the context of Mycobacterium tuberculosis infection. Chaturvedi & Henderson (2014) summarize the specific properties of copper and its toxic effect on bacteria cells. Argüello et al. (2013) review how bacteria integrate homeostatic mechanisms to avoid Cu toxicity by sensing and regulating ion chelation, chaperoning and membrane transport. 2) Microbial adaptation to host defenses: metallo-transporters or exporters. To overcome host resistance to infection, numerous mechanisms have been selected through the course of microbial evolution, in particular transporters that can feed the bacteria even at low metal concentration or, on the contrary, metallo-exporters that can expel metals outside the cell to avoid toxic accumulation. The articles in this section describe the microbial transport arsenal, and its regulation, which play major roles to influence metal economy at the host-microbe interface. Bacterial and fungal strategies to acquire Fe is the subject of four contributions. Liu & Biville (2013) discuss erythrocyte parasitism by Bartonella, transmitted by arthropod vectors and relying principally on heme capture and oxidative stress defense to cause persistent infections. Runyen-Janecky (2013) highlights some of the recent findings on heme iron acquisition system and the regulation of their expression in Gram-negative pathogens. Cornelis & Dingemans (2013) recap how Pseudomonas adapts means of iron capture to the type of infection it establishes, acute or chronic. Caza & Kronstad (2013) contrast strategies of virulent bacteria and fungi to subvert host immunity and steal iron from hemoglobin, heme, transferrin and lactoferrin or elemental iron using specialized uptake systems and siderophores. Five papers deal with microbial homeostasis of other metals Mn, Ni and Zn. Honsa et al. (2013) review the roles of importers and exporters of Mn, Fe, Zn and Cu in Streptococcus pneumoniae gene regulation and tissue-specific pathogenesis. Guilhen et al (2013) focus on families of exporters and the role of metal efflux in the evolution of Neisseria meningitidis virulence and naso-pharyngeal c

The use of microbial plant protection products is growing and their importance will strongly increase due to political and public pressure. World population is growing and the amount of food needed by 2050 will be double of what is produced now whereas the area of agricultural land is decreasing. We must increase crop yield in a sustainable way. Chemical plant growth promoters must be replaced by microbiological products. Also here, the use of microbial products is growing and their importance will strongly increase. A growing area of agricultural land is salinated. Global warming will increase this process. Plants growth is inhibited by salt or even made impossible and farmers tend to disuse the most salinated lands. Microbes have been very successfully used to alleviate salt stress of plants. Chemical pollution of land can make plant growth difficult and crops grown are often polluted and not suitable for consumption. Microbes have been used to degrade these chemical pollutants.

Over the last three decades a lot of research on the role of metals in biochemistry and medicine has been done. As a result many structures of biomolecules with metals have been characterized and medicinal chemistry studied the effects of metal containing drugs. This new book (from the EIBC Book Series) covers recent advances made by top researchers in the field of metals in cells [the “metallome”] and include: regulated metal ion uptake and trafficking, sensing of metals within cells and across tissues, and identification of the vast cellular factors designed to orchestrate assembly of metal cofactor sites while minimizing toxic side reactions of metals. In addition, it features aspects of metals in disease, including the role of metals in neuro-degeneration, liver disease, and inflammation, as a way to highlight the detrimental effects of mishandling of metal trafficking and response to "foreign" metals. With the breadth of our recently acquired understanding of metals in cells, a book that features key aspects of cellular handling of inorganic elements is both timely and important. At this point in our understanding, it is worthwhile to step back and take an expansive view of how far our understanding has come, while also highlighting how much we still do not know. The content from this book will publish online, as part of EIBC in December 2013, find out more about the Encyclopedia of Inorganic and Bioinorganic Chemistry, the essential online resource for researchers and students working in all areas of inorganic and bioinorganic chemistry.

Beginning with the germ theory of disease in the 19th century and extending through most of the 20th century, microbes were believed to live their lives as solitary, unicellular, disease-causing organisms . This perception stemmed from the focus of most investigators on organisms that could be grown in the laboratory as cellular monocultures, often dispersed in liquid, and under ambient conditions of temperature, lighting, and humidity. Most such inquiries were designed to identify microbial pathogens by satisfying Koch's postulates.3 This pathogen-centric approach to the study of microorganisms produced a metaphorical "war" against these microbial invaders waged with antibiotic therapies, while simultaneously obscuring the dynamic relationships that exist among and between host organisms and their associated microorganisms-only a tiny fraction of which act as pathogens. Despite their obvious importance, very little is actually known about the processes and factors that influence the assembly, function, and stability of microbial communities. Gaining this knowledge will require a seismic shift away from the study of individual microbes in isolation to inquiries into the nature of diverse and often complex microbial communities, the forces that shape them, and their relationships with other communities and organisms, including their multicellular hosts. On March 6 and 7, 2012, the Institute of Medicine's (IOM's) Forum on Microbial Threats hosted a public workshop to explore the emerging science of the "social biology" of microbial communities. Workshop presentations and discussions embraced a wide spectrum of topics, experimental systems, and theoretical perspectives representative of the current, multifaceted exploration of the microbial frontier. Participants discussed ecological, evolutionary, and genetic factors contributing to the assembly, function, and stability of microbial communities; how microbial communities adapt and respond to environmental stimuli; theoretical and experimental approaches to advance this nascent field; and potential applications of knowledge gained from the study of microbial communities for the improvement of human, animal, plant, and ecosystem health and toward a deeper understanding of microbial diversity and evolution. The Social Biology of Microbial Communities: Workshop Summary further explains the happenings of the workshop.