Showing papers in "Advances in Applied Microbiology in 2009"

The capsule of the fungal pathogen Cryptococcus neoformans

Abstract: The capsule of the fungal pathogen Cryptococcus neoformans has been studied extensively in recent decades and a large body of information is now available to the scientific community Well-known aspects of the capsule include its structure, antigenic properties and its function as a virulence factor The capsule is composed primarily of two polysaccharides, glucuronoxylomannan (GXM) and galactoxylomannan (GalXM), in addition to a smaller proportion of mannoproteins (MPs) Most of the studies on the composition of the capsule have focused on GXM, which comprises more than 90% of the capsule's polysaccharide mass It is GalXM, however, that is of particular scientific interest because of its immunological properties The molecular structure of these polysaccharides is very complex and has not yet been fully elucidated Both GXM and GalXM are high molecular mass polymers with the mass of GXM equaling roughly 10 times that of GalXM Recent findings suggest, however, that the actual molecular weight might be different to what it has traditionally been thought to be In addition to their structural roles in the polysaccharide capsule, these molecules have been associated with many deleterious effects on the immune response Capsular components are therefore considered key virulence determinants in C neoformans, which has motivated their use in vaccines and made them targets for monoclonal antibody treatments In this review, we will provide an update on the current knowledge of the C neoformans capsule, covering aspects related to its structure, synthesis and particularly, its role as a virulence factor

Microbial deterioration of stone monuments--an updated overview

Abstract: Cultural heritage monuments may be discolored and degraded by growth and activity of living organisms. Microorganisms form biofilms on surfaces of stone, with resulting aesthetic and structural damage. The organisms involved are bacteria (including actinomycetes and cyanobacteria), fungi, archaea, algae, and lichens. Interactions between these organisms and stone can enhance or retard the overall rate of degradation. Microorganisms within the stone structure (endoliths) also cause damage. They grow in cracks and pores and may bore into rocks. True endoliths, present within the rock, have been detected in calcareous and some siliceous stone monuments and are predominantly bacterial. The taxonomic groups differ from those found epilithically at the same sites. The nature of the stone substrate and the environmental conditions influence the extent of biofilm colonization and the biodeterioration processes. A critical review of work on microbial biofilms on buildings of historic interest, including recent innovations resulting from molecular biology, is presented and microbial activities causing degradation are discussed.

Microbial processes in oil fields: culprits, problems, and opportunities.

Abstract: Our understanding of the phylogenetic diversity, metabolic capabilities, ecological roles, and community dynamics of oil reservoir microbial communities is far from complete. The lack of appreciation of the microbiology of oil reservoirs can lead to detrimental consequences such as souring or plugging. In contrast, knowledge of the microbiology of oil reservoirs can be used to enhance productivity and recovery efficiency. It is clear that (1) nitrate and/or nitrite addition controls H2S production, (2) oxygen injection stimulates hydrocarbon metabolism and helps mobilize crude oil, (3) injection of fermentative bacteria and carbohydrates generates large amounts of acids, gases, and solvents that increases oil recovery particularly in carbonate formations, and (4) nutrient injection stimulates microbial growth preferentially in high permeability zones and improves volumetric sweep efficiency and oil recovery. Biosurfactants significantly lower the interfacial tension between oil and water and large amounts of biosurfactant can be made in situ. However, it is still uncertain whether in situ biosurfactant production can be induced on the scale needed for economic oil recovery. Commercial microbial paraffin control technologies slow the rate of decline in oil production and extend the operational life of marginal oil fields. Microbial technologies are often applied in marginal fields where the risk of implementation is low. However, more quantitative assessments of the efficacy of microbial oil recovery will be needed before microbial oil recovery gains widespread acceptance.

Biochemistry, physiology and biotechnology of sulfate-reducing bacteria.

Abstract: Chemolithotrophic bacteria that use sulfate as terminal electron acceptor (sulfate-reducing bacteria) constitute a unique physiological group of microorganisms that couple anaerobic electron transport to ATP synthesis. These bacteria (220 species of 60 genera) can use a large variety of compounds as electron donors and to mediate electron flow they have a vast array of proteins with redox active metal groups. This chapter deals with the distribution in the environment and the major physiological and metabolic characteristics of sulfate-reducing bacteria (SRB). This chapter presents our current knowledge of soluble electron transfer proteins and transmembrane redox complexes that are playing an essential role in the dissimilatory sulfate reduction pathway of SRB of the genus Desulfovibrio. Environmentally important activities displayed by SRB are a consequence of the unique electron transport components or the production of high levels of H(2)S. The capability of SRB to utilize hydrocarbons in pure cultures and consortia has resulted in using these bacteria for bioremediation of BTEX (benzene, toluene, ethylbenzene and xylene) compounds in contaminated soils. Specific strains of SRB are capable of reducing 3-chlorobenzoate, chloroethenes, or nitroaromatic compounds and this has resulted in proposals to use SRB for bioremediation of environments containing trinitrotoluene and polychloroethenes. Since SRB have displayed dissimilatory reduction of U(VI) and Cr(VI), several biotechnology procedures have been proposed for using SRB in bioremediation of toxic metals. Additional non-specific metal reductase activity has resulted in using SRB for recovery of precious metals (e.g. platinum, palladium and gold) from waste streams. Since bacterially produced sulfide contributes to the souring of oil fields, corrosion of concrete, and discoloration of stonework is a serious problem, there is considerable interest in controlling the sulfidogenic activity of the SRB. The production of biosulfide by SRB has led to immobilization of toxic metals and reduction of textile dyes, although the process remains unresolved, SRB play a role in anaerobic methane oxidation which not only contributes to carbon cycle activities but also depletes an important industrial energy reserve.

Chapter 4 In Vitro Biofilm Models. An Overview

Abstract: Observing naturally occurring biofilms in situ or ex situ has revealed the wide distribution of sessile microbial communities. The ubiquity, variety and complexity of biofilms is now widely accepted by microbiologists. While they are associated with many beneficial functions such as nutrient cycling, bioremediation and colonization resistance, adverse effects including recalcitrance, their involvement in industrial fouling, contamination and infection have made biofilms a priority research topic. We know that most biofilms, other than within certain infections and laboratory flasks, are composed of multiple species and that there is arguably no unifying biofilm architecture. Biofilms do however share certain properties including the presence of gradients of nutrients, gasses and metabolic products, relatively increased cell density, deposition of extracellular polymeric substances and marked recalcitrance towards antimicrobial treatments. Much of our understanding of biofilm physiology and micro-ecology originates from experiments using in vitro biofilm models. Broadly speaking, such models may be used to replicate environmental conditions within the laboratory or to focus on selected variables such a growth rate or fluid flow, etc. This chapter provides an overview of some commonly used biofilm models including microtitre plate systems, flow cells, the constant depth film fermenter, annular reactors and the perfused biofilm fermenter. While perfused biofilm fermenters, in particular, enable growth rate to be controlled within thin, relatively homogenous, quasi steady-state biofilms through modulation of flow rate nutrient availability, other models provide representative modelling of in situ conditions where steady states may be uncommon.

Chapter 2: Biogenesis of the cell wall and other glycoconjugates of Mycobacterium tuberculosis.

Abstract: The re-emergence of tuberculosis in its present-day manifestations - single, multiple and extensive drug-resistant forms and as HIV-TB coinfections - has resulted in renewed research on fundamental questions such as the nature of the organism itself, Mycobacterium tuberculosis, the molecular basis of its pathogenesis, definition of the immunological response in animal models and humans, and development of new intervention strategies such as vaccines and drugs. Foremost among these developments has been the precise chemical definition of the complex and distinctive cell wall of M. tuberculosis, elucidation of the relevant pathways and underlying genetics responsible for the synthesis of the hallmark moieties of the tubercle bacillus such as the mycolic acid-arabinogalactan-peptidoglycan complex, the phthiocerol- and trehalose-containing effector lipids, the phosphatidylinositol-containing mannosides, lipomannosides and lipoarabinomannosides, major immunomodulators, and others. In this review, the laboratory personnel who have been the focal point of some to these developments review recent progress towards a comprehensive understanding of the basic physiology and functions of the cell wall of M. tuberculosis.

Bacterial L-Forms

Abstract: L-forms are "cell wall-deficient" bacteria which are able to grow as spheroplasts or protoplasts. They can be differentiated into four types depending on their ability to revert to the parental, cell-walled form and to the extent of their cell-wall modification. L-forms are significant in modern science because of their contributions to an improved understanding of principal questions and their interactions with eukaryotes. This review particularly focuses on research using stable protoplast-type L-forms which have contributed to a better understanding of the structural and functional organisation of the cytoplasmic membrane and of cell division. These L-forms, which have only a single surrounding bilayer membrane, also represent a unique expression system for production of recombinant proteins. A large proportion of L-form publications concern their putative role in human disease and its therapy, a topic which is discussed briefly. L-forms have also been used to form intracellular associations with plant cells and have been shown to elicit induced disease resistance offering a novel method for plant protection. The recent decline in active research on L-forms is a concern as knowledge and experience, as well as unique L-form strains which have been maintained for decades, are being lost.

Chapter 1: Variation in form and function the helix-turn-helix regulators of the GntR superfamily.

Abstract: One of the most abundant and widely distributed groups of Helix-turn-helix (HTH) transcription factors is the metabolite-responsive GntR family of regulators (>8500 members in the Pfam database; Jan 2009). These proteins contain a DNA-binding HTH domain at the N terminus of the protein and an effector-binding and/or oligomerisation domain at the C terminus, where upon on binding an effector molecule, a conformational change occurs in the protein which influences the DNA-binding properties of the regulator resulting in repression or activation of transcription. This review summarises what we know about the distribution, structure, function and classification of these regulators and suggests that they may have a future role in biotechnology.

Nucleoid-associated proteins and bacterial physiology.

Abstract: Bacterial physiology is enjoying a renaissance in the postgenomic era as investigators struggle to interpret the wealth of new data that has emerged and continues to emerge from genome sequencing projects and from analyses of bacterial gene regulation patterns using whole-genome methods at the transcriptional and posttranscriptional levels Information from model organisms such as the Gram-negative bacterium Escherichia coli is proving to be invaluable in providing points of reference for such studies An important feature of this work concerns the nature of global mechanisms of gene regulation where a relatively small number of regulatory proteins affect the expression of scores of genes simultaneously The nucleoid-associated proteins, especially Factor for Inversion Stimulation (Fis), IHF, H-NS, HU, and Lrp, represent a prominent group of global regulators and studies of these proteins and their roles in bacterial physiology are providing new insights into how the bacterium governs gene expression in ways that maximize its competitive advantage

Virulence in Cryptococcus species.

Abstract: Cryptococcus neoformans and Cryptococcus gattii are the cause of life-threatening meningoencephalitis in immunocompromised and immunocompetent individuals respectively. The increasing incidence of cryptococcal infection as a result of the AIDS epidemic, the recent emergence of a hypervirulent cryptococcal strain in Canada and the fact that mortality from cryptococcal disease remains high have stimulated intensive research into this organism. Here we outline recent advances in our understanding of C. neoformans and C. gattii, including intraspecific complexity, virulence factors, and key signaling pathways. We discuss the molecular basis of cryptococcal virulence and the interaction between these pathogens and the host immune system. Finally, we discuss future challenges in the study and treatment of cryptococcosis.

Phage evolution and ecology.

Abstract: Bacteriophages (phages) are the viruses of bacteria and the study of phage biology can be differentiated, roughly, into molecular, environmental, evolutionary, ecological, and applied aspects. While for much of the past fifty-plus years molecular and then applied aspects have dominated the field, more recently environmental concerns, especially the phage impact on biogeochemical cycles, have driven an increase in the appreciation of phage ecology. Over approximately the same time frame, decreasing sequencing costs have combined with phage molecular characterization to give rise to an inescapable consideration of phage comparative genomics. That, along with environmental metagenomics, has stimulated, especially among molecular biologists, a more general interest in phage evolutionary biology. However, while reviews of phage ecology have become exceedingly common, overviews of phage evolutionary biology are comparatively rare, and broad considerations of phage evolutionary biology drawn from an ecological perspective rarer still. In this chapter I jump into this latter void, providing an overview of phage evolutionary biology as viewed from the perspective of phage-environment interactions, that is, from the perspective of phage ecology. This I do over five sections constituting (1) an introduction to phages and how, phenotypically, they can be differentiated into three basics types that correlate, more or less, with genomic size, that is, tailed (generally larger genomes), lipid-containing (medium-sized genomes), and single-stranded (small genomes); (2) a brief introduction to phage ecology as considered particularly from a classical ecological perspective; (3) an extended introduction to evolutionary biology as viewed from a phage and phage-ecological standpoint; (4) phage evolutionary ecology, that is, consideration of phage adaptations from the vantage of why, in terms of phage fitness, those adaptations may have evolved; and (5) phage evolutionary biology, including evolutionary ecology, as viewed from the perspective of phage genomics.

Biodegradation of pharmaceutical and personal care products.

Abstract: Medical treatments and personal hygiene lead to the steady release of pharmaceutical and personal care products (PPCPs) into the environment Some of these PPCPs have been shown to have detrimental environmental effects and could potentially impact human health Understanding the biological transformation of PPCPs is essential for accurately determining their ultimate environmental fate, conducting accurate risk assessments, and improving PPCP removal We summarize the current literature concerning the biological transformation of PPCPs in wastewater treatment plants, the environment, and by pure cultures of bacterial isolates Although some PPCPs, such as ibuprofen, are readily degraded under most studied conditions, others, such as carbamazepine, tend to be recalcitrant This variation in the biodegradability of PPCPs can be attributed to structural differences, because PPCPs are classified by application, not chemical structure The degradation pathways of octylphenol by Sphingomonas sp strain PWE1, ibuprofen by Sphingomonas sp strain Ibu-2, and DEET by Pseudomonas putida DTB are discussed in more detail

Deciphering bacterial flagellar gene regulatory networks in the genomic era.

Abstract: Synthesis of the bacterial flagellum is a complex process involving dozens of structural and regulatory genes. Assembly of the flagellum is a highly-ordered process, and in most flagellated bacteria the structural genes are expressed in a transcriptional hierarchy that results in the products of these genes being made as they are needed for assembly. Temporal regulation of the flagellar genes is achieved through sophisticated regulatory networks that utilize checkpoints in the flagellar assembly pathway to coordinate expression of flagellar genes. Traditionally, flagellar transcriptional hierarchies are divided into various classes. Class I genes, which are the first genes expressed, encode a master regulator that initiates the transcriptional hierarchy. The master regulator activates transcription a set of structural and regulatory genes referred to as class II genes, which in turn affect expression of subsequent classes of flagellar genes. We review here the literature on the expression and activity of several known master regulators, including FlhDC, CtrA, VisNR, FleQ, FlrA, FlaK, LafK, SwrA, and MogR. We also examine the Department of Energy Joint Genomes Institute database to make predictions about the distribution of these regulators. Many bacteria employ the alternative sigma factors sigma(54) and/or sigma(28) to regulate transcription of later classes of flagellar genes. Transcription by sigma(54)-RNA polymerase holoenzyme requires an activator, and we review the literature on the sigma(54)-dependent activators that control flagellar gene expression in several bacterial systems, as well as make predictions about other systems that may utilize sigma(54) for flagellar gene regulation. Finally, we review the prominent systems that utilize sigma(28) and its antagonist, the anti-sigma(28) factor FlgM, along with some systems that utilize alternative mechanisms for regulating flagellar gene expression.

Diversity in bacterial chemotactic responses and niche adaptation

Abstract: The ability of microbes to rapidly sense and adapt to environmental changes plays a major role in structuring microbial communities, in affecting microbial activities, as well as in influencing various microbial interactions with the surroundings. The bacterial chemotaxis signal transduction system is the sensory perception system that allows motile cells to respond optimally to changes in environmental conditions by allowing cells to navigate in gradients of diverse physicochemical parameters that can affect their metabolism. The analysis of complete genome sequences from microorganisms that occupy diverse ecological niches reveal the presence of multiple chemotaxis pathways and a great diversity of chemoreceptors with novel sensory specificities. Owing to its role in mediating rapid responses of bacteria to changes in the surroundings, bacterial chemotaxis is a behavior of interest in applied microbiology as it offers a unique opportunity for understanding the environmental cues that contribute to the survival of bacteria. This chapter explores the diversity of bacterial chemotaxis and suggests how gaining further insights into such diversity may potentially impact future drug and pesticides development and could inform bioremediation strategies.

Cutinases: properties and industrial applications.

Abstract: Cutinases, also known as cutin hydrolases (EC 3.1.1.74) are enzymes first discovered from phytopathogenic fungi that grow on cutin as the sole carbon source. Cutin is a complex biopolymer composed of epoxy and hydroxy fatty acids, and forms the structural component of higher plants cuticle. These enzymes share catalytic properties of lipases and esterases, presenting a unique feature of being active regardless the presence of an oil-water interface, making them interesting as biocatalysts in several industrial processes involving hydrolysis, esterification, and trans-esterification reactions. Cutinases present high stability in organic solvents and ionic liquids, both free and microencapsulated in reverse micelles. These characteristics allow the enzyme application in different areas such as food industry, cosmetics, fine chemicals, pesticide and insecticide degradation, treatment and laundry of fiber textiles, and polymer chemistry. The present chapter describes the characteristics, potential applications, and new perspectives for these enzymes.

Bioremediation of cyanotoxins.

Abstract: Cyanobacteria are a diverse group of mainly aquatic microorganisms which occur globally. Eutrophication (nutrient enrichment) of water bodies, often as a result of human activities, results in prolific grow of cyanobacteria that develop into a thick scum or bloom. Many of these blooms are toxic due to the production of hepatotoxins (microcystins and cylindrospermopsin) and/or neurotoxins (saxitoxins and anatoxins) posing a serious health hazard to humans and animals. The presence of these cyanotoxins is of particular concern in drinking water supplies where conventional water treatment often fails to eliminate them. Hence, there is significant interest in water treatment strategies that ensure the removal of cyanotoxins, with the exploitation of microbes being on such possible approach. As naturally occurring compounds it is assumed that these toxins are readily biodegraded. Furthermore, there is no significant evidence of their accumulation in the environment and their relative stable under a wide range of physico-chemical conditions, suggests biodegradation is the main route for their natural removal from the environment. Microcystins, as the most commonly occurring toxins, have been the most widely studied and hence form the main focus here. The review provides an overview of research into the biodegradation of cyanotoxin, including evidence for natural bioremediation, screening and isolation of toxin biodegrading bacteria, genetic and biochemical elucidation of a degradation pathway along with attempts to harness them for bioremediation through bioactive water treatment processes.

Multiple effector mechanisms induced by recombinant Listeria monocytogenes anticancer immunotherapeutics.

Abstract: Listeria monocytogenes is a facultative intracellular gram-positive bacterium that naturally infects professional antigen presenting cells (APC) to target antigens to both class I and class II antigen processing pathways. This infection process results in the stimulation of strong innate and adaptive immune responses, which make it an ideal candidate for a vaccine vector to deliver heterologous antigens. This ability of L. monocytogenes has been exploited by several researchers over the past decade to specifically deliver tumor-associated antigens that are poorly immunogenic such as self-antigens. This review describes the preclinical studies that have elucidated the multiple immune responses elicited by this bacterium that direct its ability to influence tumor growth.

Temperature sensors of eubacteria.

Abstract: In their natural habitats, bacteria are frequently exposed to sudden changes in temperature. It has been shown that bacteria use different strategies to cope with temperature changes. These strategies are genetically determined and start with registration of the temperature followed by the induction of a subset of genes allowing them to adapt to the stressful situation. Four different mechanisms have evolved termed the high and the low temperature response and the heat and the cold shock response. These temperature changes are registered by three different thermosensors: DNA, RNA and protein.

Molecular networks in the fungal pathogen Candida albicans.

Abstract: Candida albicans is an important opportunistic fungal pathogen of humans. Its success as a commensal and pathogen extends from its ability to switch between both yeast and hyphal growth forms. Therefore, extensive research on this fungus has also focused on the identification and understanding of the regulatory networks behind this morphological switch. Here we review established signaling pathways, including the mitogen-activated protein kinase cascades and the cyclic AMP-dependent protein kinase A signaling pathway. In addition, we focus on new developments in the rapidly growing area of fungal environmental sensing, but importantly also highlight exciting new developments in the expanding field of molecular networks involved in fungal-fungal and fungal-bacterial interkingdom communication.

Chapter 6: The genomes of lager yeasts.

Abstract: Yeasts used in the production of lagers belong to the genus Saccharomyces pastorianus. Species within this genus arose from a natural hybridization event between two yeast species that appear to be closely related to Saccharomyces cerevisiae and Saccharomyces bayanus. The resultant hybrids contain complex allopolyploid genomes and retain genetic characteristics of both parental species. Recent genome analysis using both whole genome sequencing and competitive genomic hybridization techniques has revealed the underlying composition of lager yeasts genomes. There appear to be at least 36 unique chromosomes, many of which are lager specific, resulting from recombination events between the homeologous parental chromosomes. The recombination events are limited to a defined set of genetic loci, which are highly conserved within strains of lager yeasts. In addition to the hybrid chromosomes, several non-reciprocal chromosomal translocations and inversions are also observed. Remarkably, in response to exposure to environmental stresses such as high temperatures and high osmotic pressure, the genomes appear to be highly dynamic and undergo recombination events at defined loci and alterations in the telomeric regions. The ability of environmental stress to alter the structure and composition of the genomes of lager yeasts may point to mechanisms of adaptive evolution in these species.

Chapter 6 Posttranscriptional Gene Regulation in Kaposi's Sarcoma‐Associated Herpesvirus

Abstract: Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi's sarcoma, primary effusion lymphoma and some cases of multicentric Castleman's disease To understand the pathogenesis and life cycle of KSHV, significant focus has been placed on determining how KSHV factors influence viral and cellular gene expression The importance of transcriptional regulation by KSHV is well documented, but several KSHV posttranscriptional regulators are also essential for KSHV replication and pathogenesis KSHV miRNAs regulate translation and stability of cellular mRNAs that may be important for tumorigenesis The ORF57 protein has been reported to enhance several posttranscriptional processes including viral mRNA export, RNA stability and pre-mRNA splicing SOX, Kaposin B and the PAN-ENE regulate the stability of viral or cellular transcripts Together, these observations point to the importance of posttranscriptional regulation in KSHV With the growing appreciation of posttranscriptional regulation in cellular gene expression, it seems likely that the list of viral posttranscriptional regulatory schemes will expand as new details of KSHV gene regulation are uncovered

Baculovirus interactions in vitro and in vivo.

Abstract: Baculoviruses are promising viral insecticides and are safe for the environment. Interaction of baculoviruses in vitro and in vivo is a basic molecular and ecological question that has practical applications in agriculture. Cellular secretion is also a fundamental property in cell-cell communication. Here, we review recent investigations on how baculoviruses interact with insect cells and insect hosts. We focus particularly on a new interaction mechanism in which a secretion from cells infected with one virus enhances infection by a second virus. We also discuss a hypothesis that the secreted signals may serve as ligands that bind to the receptors on the surface of the cells that harbor the suppressed genomes of Thysanoplusia orichalcea MNPV (ThorMNPV) in Sf21 and Spodoptera exigua MNPV (SeMNPV) in High 5 to initiate signal transduction leading to the activation of genome replication of ThorMNPV in Sf21 and SeMNPV in High 5. We also discuss how the enhanced replication of SeMNPV replication by Autographa californica MNPV (AcMNPV) in nonpermissive insect cells depends on the types of cells. Interaction of baculoviruses in insects focused on mutualism and antagonism, even though the mechanism is not clear on mutualism. The antagonism of a Nucleopolyhedrovirus (NPV) with a Granulovirus (GV) has been extensively studied by a metalloprotein in the capsule of GV that disrupts the peritrophic membrane, a physical barrier to NPV entry to the midgut of larvae, to facilitate NPV infection.

Biotechnological applications of recombinant microbial prolidases.

Abstract: Prolidase is a metallopeptidase that is ubiquitous in nature and has been isolated from mammals, bacteria and archaea. Prolidase specifically hydrolyzes dipeptides with a prolyl residue in the carboxy terminus (NH2–X–/–Pro–COOH). Currently, the only solved structure of prolidase is from the hyperthermophilic archaeon Pyrococcus furiosus. This enzyme is of particular interest because it can be used in many biotechnological applications. Prolidase is able to degrade toxic organophosphorus (OP) compounds, namely, by cleaving the P–F and P–O bonds in the nerve agents, sarin and soman. Applications using prolidase to detoxify OP nerve agents include its incorporation into fire‐fighting foams and as biosensors for OP compound detection. Prolidases are also employed in the cheese‐ripening process to improve cheese taste and texture. In humans, prolidase deficiency (PD) is a rare autosomal recessive disorder that affects the connective tissue. Symptoms of PD include skin lesions, mental retardation and recurrent respiratory infections. Enzyme replacement therapies are currently being studied in an effort to optimize enzyme delivery and stability for this application. Previously, prolidase has been linked to collagen metabolism and more recently is being associated with melanoma. Increased prolidase activity in melanoma cell lines has lead investigators to create cancer prodrugs targeting this enzyme. Thus, there are many biotechnological applications using recombinant and native forms of prolidase and this review will describe the biochemical and structural properties of prolidases as well as discuss their most current applications.

Chapter 3 Antimicrobial Properties of Hydroxyxanthenes

Abstract: Hydroxyxanthenes are commonly used as dyestuffs in the food, cosmetics, and textile industries. These compounds also have medical applications due to their unique staining and fluorescent properties. The halogenated hydroxyxanthenes exhibit antimicrobial properties that may be useful for reducing or eliminating bacterial pathogens from a variety of environments, including drinking water and food products. Antimicrobial characteristics of Eosin, Erythrosine, Phloxine, and Rose Bengal have been known for many years, but their application as antimicrobial agents has been limited primarily to selective agents in microbiological growth media. The primary mechanism of bacterial inactivation by hydroxyxanthenes is photooxidation. When halogenated hydroxyxanthenes are photooxidized, a variety of compounds are produced (e.g., singlet oxygen, superoxide anion and other radicals); these exhibit toxicity to the microbial cell. Gram-positive bacteria are particularly sensitive to inactivation by photooxidation of halogenated hydroxyxanthenes; however, different species vary in their sensitivity. Gram-negative bacteria are inherently resistant to inactivation by these compounds due to the barrier properties of the outer membrane that prevent the necessary localization. Treatments such as chelation and ultrahigh pressure may be used to destabilize the outer membrane leading to sensitivity of Gram-negative bacteria to halogenated hydroxyxanthenes.

Genetic tools to study gene expression during bacterial pathogen infection.

Abstract: The study of bacterial pathogenesis is in many ways the study of the regulatory mechanisms at work in the microbe during infection The astonishing flexibility and adaptability of the bacterial cell has enabled many pathogenic species to freely transition between dramatically different environmental conditions The transcriptional changes that underlie this ability can determine the success of the pathogen in the host Many techniques have been devised to examine the transcriptional repertoire of bacteria in vivo during infection Here, we review a class of technologies known as in vivo expression technology (IVET), which use promoter-trapping with a variety of different reporter constructs to allow researchers to probe the transcriptional changes taking place in bacteria under various environmental conditions Using IVET techniques, researchers have been able to catalogue a wide variety of virulence factors in the host for several important human pathogens, as well as examining the timing of virulence gene regulation Most recently, IVET techniques have also been used to identify transcriptional repression events in vivo, such as the suppression of anti-colonization factors deleterious to infection As the array of IVET reporters and promoter-trapping strategies grow, researchers are increasingly able to illuminate the myriad transcriptional activities that allow bacteria to survive and cause disease in the host

Chapter 5: Zones of inhibition? The transfer of information relating to penicillin in Europe during World War II.

Abstract: Alexander Fleming published his first description of penicillin in 1929, but the journal articles that were to propel penicillin from its relative obscurity were those of Howard Florey and his co-workers at Oxford University. These were published in The Lancet in the early years of World War II and although wartime conditions restricted the flow of information on penicillin throughout Europe, they never succeeded in shutting it off altogether. In Germany an information-gathering initiative was established in the early phases of the war to systematically copy and distribute British and American scientific articles. A similar, though less well-resourced, operation was permitted to function in Occupied France. Both these operations were to yield up information on penicillin to their respective scientists. However, workers in other countries of occupied Europe fared less well; there was a dearth of information on penicillin in Holland but despite this, activity to produce the antibiotic still took place. Central to the production of penicillin at this time was access to a strain of Fleming's strain of Penicillium notatum, and an attempt to explain how this particular strain found its way to various European laboratories is given here.

Diagnosis of clinically relevant fungi in medicine and veterinary sciences.

Abstract: This review focuses on the most economically and epidemiologically important fungi affecting humans and animals. This paper will also summarize the different techniques, either molecular, based on nucleic acid and antibody analysis, or nonmolecular such as microscopy, culture, UV Wood';s lamp, radiology, and spectroscopy used to identify species or group of fungi assisting clinicians to take the best control approach to clear such infections. On the molecular side, the paper will review results on genome sequencing which can help colleagues to identify their own DNA/RNA tests if they are interested in the diagnostic of fungi in medicine and veterinary medicine.