"well-written essays to explore a number of microbial ecological theories from population genetic and evolution theory to microbial biogeography ... The academic content of this volume is robust and the questions posted are thought-provoking ... definitely a useful reference book for scientists" from Diane Purchase (Middlesex University, UK) writing in Microbiology Today (2013) read more ...

Microbial Ecological Theory: Current Perspectives Edited by: Lesley A. Ogilvie and Penny R. Hirsch ISBN: 978-1-908230-09-6 Publisher: Caister Academic Press Publication Date: September 2012 Cover: hardback "thought-provoking ... a useful reference book" (Microbiol. Today)

from Paul Wilmes writing in Microbial Ecological Theory: Current Perspectives:

The recent application of high-throughput molecular biology methods to natural microbial communities is profoundly changing our view on the microbial world. In particular, our understanding of microbial population-level differentiation involved in ecological adaptation that leads to microbial divergence and speciation has been profoundly altered. Numerous processes that underlie microbial differentiation have been identified but determining the relative significance of these processes remains challenging. For example, a major unresolved question is how much of observed genetic heterogeneity is due to neutral versus adaptive processes. Sequence-based and modelling analyses suggest that much of the observed variation is neutral but recent functional "meta-OMIC" data suggest that at least some of this fine-scale variation is functionally relevant and, thus, involved in adaption and divergence. From the limited amount of largely disjointed metagenomic and functional data obtained to date, extensive intra- and inter-system as well as extensive intra- and inter-population differences are apparent. Consequently, it is difficult to ascertain specific molecular patterns that define specific microbial groups that would be congruent with the definition of a microbial species. Future concomitant analysis of community genomic complements, transcriptomes, proteomes and metabolomes over relevant spatial and temporal scales will result in detailed molecular descriptions of distinct taxonomic entities. Such a system-level molecular organismal classification system will need to be solidly grounded in ecological theory, population genetic theory and evolutionary theory, and may be universally applicable to the three domains of life.

Further reading: Microbial Ecological Theory: Current Perspectives

from Zhanshan (Sam) Ma, Jiawei Geng, Zaid Abdo and Larry J. Forney writing in Microbial Ecological Theory: Current Perspectives:

Microbial community dynamics is one of the most important central themes of microbial community ecology, which seems to be experiencing its first golden era thanks to the rapidly expanding datasets derived using metagenomic and other "omics" methods in microbial biology. For example, much of the ongoing NIH-HMP (Human Microbiome Project) focus has been centered on the dynamics of human microbiome communities. Microbial ecologists are beginning to actively draw upon ecological theories from macro ecology to study microbial communities. In this article, we present a brief review on several selected topics of ecological theories that are most relevant to community dynamics, including the diversity-stability paradigm, intermediate disturbance hypothesis (IDH), species area/time curves (SAT), species abundance distribution (SAD), and neutral community theory. In perspective, we suggest that the study of microbial community dynamics can not only benefit from applying ecological theories originally developed in macro ecology, but also contribute to the development and testing of new ecological theories. These bidirectional interactions are of critical importance to the flourishing of theoretical microbial ecology, and studies of microbial community dynamics offers tremendous opportunities for these intellectual exchanges to occur.

Further reading: Microbial Ecological Theory: Current Perspectives

from Mathilde H. Josefsen, Charlotta Löfström, Trine Hansen, Eyjólfur Reynisson and Jeffrey Hoorfar writing in Quantitative Real-time PCR in Applied Microbiology:

The polymerase chain reaction has revolutionized the world of scientific research and its broad application has caused a tremendous development of versatile PCR instruments and chemistries to fit its purpose. This chapter provides the reader with a general introduction to the basics of real-time PCR instrumentation, including the thermal and optical systems and the software. Performance parameters such as temperature uniformity, accuracy and ramp speed as well as reaction format, optical systems, calibration of dyes, software and comparison between different real-time PCR platforms will be discussed from a user perspective leading to an instrument selection guide. Differences between fluorescent DNA binding dyes and target-specific fluorescently labeled primers or probes for detection of amplicon accumulation will be discussed, along with the properties and applications of the most frequently applied chemistries. The fluorophores and quenchers used for primer and probe labeling and their compatibility will be presented, and finally the future challenges and trends within the field of qPCR instrumentation will be discussed.

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from Diego Fontaneto and Joaquín Hortal writing in Microbial Ecological Theory: Current Perspectives:

The distribution of microscopic organisms (that is, those smaller than 2 mm) has been historically considered non relevant for biogeography, because of the idea that due to their small size, dispersal abilities, resting stages and quick reproductive rates, the presence of microscopic organisms in any place was not limited by geographical barriers and distances. Recent studies challenge this idea, and provide theoretical and empirical evidence in support of the existence of spatial patterns at different scales, and of biogeographical processes affecting many groups of microscopic organisms. Here we review the current state of the art for microbial biogeography, summarising sources of problems and misconceptions, but also their solutions advancing the general understanding of biogeography, and conclude suggesting new avenues for future research.

Further reading: Microbial Ecological Theory: Current Perspectives

from Vijay J. Gadkar and Martin Filion writing in Quantitative Real-time PCR in Applied Microbiology:

Environmental matrices are highly diverse in their composition and range from simple (e.g. water) to highly complex (e.g. organic soils/biosolids). Analysis of microbial gene expression from such substrates is done for variety of purposes which could range from bio-surveillance to elucidation of biological function of a target microbe. Quantitative real-time PCR (RT-qPCR) has become a technique of choice for studying such bio-processes, due to its unique ability to both detect and quantify a target transcript in real-time. Challenges in extracting inhibitor-free, structurally intact RNA, amenable for a sensitive technique like RT-qPCR, has however proved to be a major impediment in our ability to rigorously implement this highly versatile technology. Despite these "substrate defined" limitations, many attempts have been made to implement the RT-qPCR technology. Efforts like these have given us invaluable insight into the expression status of a particular transcript and hence, the biological functioning of the microbe, specifically under natural in situ conditions. As a result, it has enhanced our understanding of the role and diversity of many microbial populations which, previously was not possible using conventional molecular approaches. In this chapter, we have sought to summarize such technical problems faced by molecular environmental microbiologist and solutions developed to mitigate those challenges.

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from Penny R Hirsch and Tim H. Mauchline writing in Microbial Ecological Theory: Current Perspectives:

Mutualism is responsible for the genesis of green plants and is implicated in their colonisation of land. Current knowledge of plant-microorganism symbioses includes a range of associations with different degrees of intimacy and mutual dependence but the mutual benefits are not always clear. Complex signalling is involved when the plant immune system recognises beneficial endosymbionts although many have also evolved mechanisms to evade or moderate plant defence pathways. A wide range of bacteria inhabit intercellular spaces but only a few are true endosymbionts able to penetrate living cells whilst remaining membrane-bound, accessing plant carbon compounds in a manner analogous to biotrophic pathogens. Unlike pathogens, they provide nutrients to the plant in exchange. The best-known examples are rhizobia, bacteria that induce root nodules on leguminous plants and fix atmospheric nitrogen; and arbuscular mycorrhizal fungi that sequester phosphate and organic N from soil and provide it to their plant hosts. Both secrete factors prior to contacting plant cells which appear to prepare the hosts for mutual rather than pathogenic interactions and suppress the defence mechanisms. The processes involved in these symbioses are compared to less intimate interactions and the nature of mutualism is discussed.

Further reading: Microbial Ecological Theory: Current Perspectives

"reviews and illustrates the use of quantitative real-time PCR for a number of different purposes. It covers the basic process as well as the technology that has improved its performance, while also exploring the various scientific fields that use this technique routinely. It provides a complete description of what scientists need to design and perform a quantitative PCR ... useful to scientists in many different types of laboratories, including public health, environmental, clinical diagnostic, and food industry. It also can be useful to students and young investigators as well as experienced scientists. The authors clearly are familiar with the development and application of quantitative PCR and share their experience here ... This useful book is filled with valuable information for any laboratory using PCR to detect microbial agents and will serve as a resource for many years to come. " from Rebecca T. Horvat (University of Kansas, USA) writing in Doodys read more ...

Quantitative Real-time PCR in Applied Microbiology Edited by: Martin Filion ISBN: 978-1-908230-01-0 Publisher: Caister Academic Press Publication Date: May 2012 Cover: hardback "useful book ... filled with valuable information" (Doodys)

from Luca Cocolin and Kalliopi Rantsiou writing in Quantitative Real-time PCR in Applied Microbiology:

Since its first application in food microbiology in the late '90s, quantitative PCR (qPCR) has attracted the interest of researchers, working mainly in the field of food safety, but lately also of microbiologists studying spoilage and fermentation processes. In addition to the advantages that conventional PCR offers in microbiological testing, i.e. specificity, reduced time of analysis and detection of viable but not culturable cells, qPCR allows quantification of target populations. This aspect is particularly relevant for foodborne pathogens, for which specific microbiological criteria exist, but also for spoilage and technological important microorganisms, in order to follow their population kinetics in foods. Although advancements in food microbiology have been made from its application, qPCR has not yet been utilized to its full potential: the quantification step is only rarely carried out and qPCR is often used as an alternative of conventional PCR. In this chapter we will critically describe the application of qPCR in food microbiology based on the available literature, taking into account the specific problems and suggesting some possible solutions.

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from Claudia Goyer and Catherine E. Dandie writing in Quantitative Real-time PCR in Applied Microbiology:

Development of quantitative PCR (qPCR) has facilitated major advances in assessment of microbial community abundances in complex environmental samples including water, soil, sediments, compost and manure and in our understanding of factors influencing community sizes in situ. qPCR has increasingly been used in environmental studies due to its sensitivity, ease of use, and the capacity to run large numbers of samples. However, qPCR has some limitations, which are specifically caused by the nature of environmental samples, including the variability in microorganism distribution, the efficiency of DNA recovery and purification, and the amount and type of PCR inhibitors co-extracted with the target nucleic acids. The heterogeneity of the templates amplified by qPCR can generate PCR biases and artifacts. Accuracy of the quantification of broad groups of microorganisms is influenced by the number of gene copies per genome of the selected marker. In this review, we will discuss the main experimental considerations for using qPCR in environmental studies, including the factors affecting key steps in the process of performing quantification of microorganisms in environmental samples. Although quantification of microorganisms is challenging, it is possible to reliably quantify microorganisms in complex environmental samples using qPCR. We will also briefly review the findings of studies which have used qPCR to quantify microorganisms from complex matrices.

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from Lia C.R.S. Teixeira and Etienne Yergeau writing in Quantitative Real-time PCR in Applied Microbiology:

Quantitative polymerase chain reaction (qPCR) represents an effective method to quantify genes or transcripts within environmental samples. For that reason, qPCR has been widely used to characterize the functional patterns of complex microbial communities. In this chapter we summarize some recent applications of different qPCR approaches targeting functional genes encoding key enzymes in the N-, C- and S-cycles and also functional genes related to antibiotic resistance. We also point out some limitation of qPCR approaches. The ongoing development of new molecular techniques, like metagenomics, will have positive impacts on the specificity and the coverage of qPCR assays, since the availability of more sequence data will help to improve the design of primers targeting functional genes.

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from Michael W. Pfaffl writing in Quantitative Real-time PCR in Applied Microbiology:

The present chapter describes the quantification strategies used in real-time RT-PCR (RT-qPCR), focusing on the main elements that are essential to fulfil the MIQE guidelines. The necessity of initial proper data adjustment and background correction is discussed to allow reliable quantification. The advantages and disadvantages of the absolute and relative quantification approaches are also described. In conjunction with relative quantification, the importance of an amplification efficiency correction is shown, and software tools that are available to calculate relative expression changes are presented.

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from Dan Tulpan, Michelle Davey and Mark Laflamme writing in Quantitative Real-time PCR in Applied Microbiology:

The ability of DNA microarray technology to identify and quantify microbial entities and genes of interest in various environments, such as soil, water, air, compost, and blood, propelled biological, environmental and clinical research into the post-genomic era. Nevertheless, as it is valid for any new technology, errors may occur at different stages along the experimental process. Three sources of errors associated with DNA microarray utilization have been identified by Taniguchi et al. (2001), namely: (i) the microarray fabrication, (ii) the microarray experiment, and (iii) the interpretation of results (data analysis). Validation strategies are typically required to alleviate and eventually repair the undesired errors that may arise in a microarray experiment. One of the validation techniques widely accepted and used worldwide is the quantitative Reverse Transcriptase Polymerase Chain Reaction (RT-qPCR). This chapter will provide succinct introductions to microarray technologies applied to microbial research and fundamental notions regarding RT-qPCR and its use to validate microarray results. A discussion including advantages and disadvantages of microbial microarray validation using RT-qPCR will be presented and current and future trends and research directions will be summarized towards the end of the chapter.

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from Anna Oliver, Andrew K. Lilley and Christopher J. van der Gast writing in Microbial Ecological Theory: Current Perspectives:

The identification of spatial patterns and their relationships to ecological events is an important specialization within ecology which is now branching into the microbial world. In spatial ecology, the detection of patterns at a given spatial scale can be used to explain ecological mechanisms and processes. Furthermore, through the application of spatial statistical analyses, factors leading to ecological events can be determined and verified. One of the most commonly studied aspects of spatial ecology, recently applied in microbial ecology, is the species‰ÛÒarea relationship (SAR). The temporal analogue of the SAR, the species‰ÛÒtime relationship (STR), on the other hand has received far less attention, even in the science of general ecology. Like SARs, the STRs are influenced by a variety of factors including dispersal, abiotic and biotic interactions, and species-species interactions. The application of these ecological conceptual tools to microbial ecology is a rapidly developing field. This chapter proposes that the STRs are a powerful and appropriate tool for studies of microbial diversity and that they make a contribution to understanding ecological communities. From a fundamental perspective, we focus on how microbial STRs compare with those for animals and plant communities, and how they are improving our understanding of community assembly and dynamics. As we believe a key future importance of studying STRs will be for applied benefit, we also discuss how microbial STRs have been used to distinguish between anthropogenic perturbations and underlying natural dynamics and have provided ecological insights for clinical benefit in bacterial infections.

Further reading: Microbial Ecological Theory: Current Perspectives

from Lesley A. Ogilvie, Andrew D.J. Overall and Brian V. Jones writing in Microbial Ecological Theory: Current Perspectives:

Humans enter into a range of symbioses with resident and transiently colonising microbes, which span a dynamic continuum from antagonistic to mutualistic. These interactions are shaped by a complex set of selective forces, which include both host and microbially-derived selective pressures. Given the significant impact that both resident and pathogenic microbes can have on our health, there is now a move to develop a theoretical framework that may guide studies of human-microbe interactions. This should enable the deeper level of understanding required to model, predict and ultimately control human diseases related to antagonistic or aberrant host-microbe interactions. Here we explore the human‰ÛÒmicrobe coevolutionary continuum in the context of current and emerging theory, and with a focus on the opposite ends of the spectrum: mutualism and antagonism. In doing so we highlight areas in which theory is helping to enhance the understanding of this dynamic continuum and where current theory fails as well as suggesting future avenues of research.

Further reading: Microbial Ecological Theory: Current Perspectives

from Jorge Santo Domingo, Mary Schoen, Nicholas Ashbolt and Hodon Ryu writing in Quantitative Real-time PCR in Applied Microbiology:

Microbial risk assessment (MRA) has traditionally utilized microbiological data that was obtained by culture-based techniques that are expensive and time consuming. With the advent of PCR methods there is a realistic opportunity to conduct MRA studies economically, in less time, and simultaneously targeting multiple pathogens and their sources. More importantly, recently developed qPCR assays provide the opportunity to estimate the densities of the reference pathogens and their sources, which is critical to quantitative MRA (QMRA) analyses. In this chapter we discuss the use of qPCR-based methods to identify risks associated with exposure to water, namely, drinking and recreational waters. We discuss the advantages associated with the current qPCR approaches used in microbial water quality studies and critically evaluate some of the limitations as they relate to the use of QMRA in the assessment of microbial water quality and public health protection.

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from Mikael Kubista, Vendula Rusnakova, David Svec, Björn Sjögreen and Ales Tichopad writing in Quantitative Real-time PCR in Applied Microbiology:

As the qPCR field advances, the design of experiments and the analysis of data is becoming more important and more challenging. Calculation of relative expression of a reporter gene to a reference gene in pairs of samples using the ΔΔCq method is no longer sufficient. Studies are now designed using multiple markers, nested levels, exploring or confirming the effect of multiple factors, occasionally in paired designs, etc. Proper handling of such data requires software that support the planning and design of experiments, and data analysis. Several software with these capacities are emerging. This chapter describes some of the features of one of the most powerful of those: GenEx from MultiD Analysis.

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from Vijay J. Gadkar and Martin Filion writing in Quantitative Real-time PCR in Applied Microbiology:

Real time-quantitative PCR (RT-qPCR) technology has revolutionized the detection landscape in every area of molecular biology. The fundamental basis of this technology has remained unchanged since its inception, however various modifications have enhanced the overall performance of this highly versatile technology. These improvements have ranged from changes in the individual components of the enzymatic reaction cocktail (polymerizing enzymes, reaction buffers, probes, etc.) to the detection system itself (instrumentation, software, etc). The RT-qPCR technology currently available to researchers is more sensitive, faster and affordable than when this technology was first introduced. In this chapter, we summarize the developments of the last few years in RT-qPCR technology and nucleic acid amplification.

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from Stephen A Bustin, Sara Zaccara and Tania Nolan writing in Quantitative Real-time PCR in Applied Microbiology:

The real-time fluorescence-based quantitative polymerase chain reaction (qPCR) has become the benchmark technology for the detection of nucleic acids in every area of microbiology, biomedical research, biotechnology and in forensic applications. Unlike conventional (legacy) PCR, which is a qualitative end-point assay, qPCR allows accurate quantification of amplified DNA in real time during the exponential phase of the reaction. The cost of instruments and reagents is well within reach of individual laboratories, assays are easy to perform, capable of high throughput and combine high sensitivity with reliable specificity. It is possible to achieve accurate and biologically meaningful quantification if meticulous attention is paid to the details of every step of the qPCR assay, starting with sample selection, acquisition and handling through assay design, validation and optimisation. The growing awareness of the need for standardisation, quality control and the significant problems associated with inadequate reporting of the assay has resulted in the publication of guidelines for minimum information for the publication of qPCR experiments (MIQE).

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