Evolution Of Microbial Pathogens Research Articles

Green Isolation and Characterization of Marine Actinomycetes in Tharangambadi Coastal Area in Nagapattinam District, Tamil Nadu

As a result of the continuous evolution of microbial pathogens towards antibiotic-resistance, therefore development of new and effective antimicrobial compounds. Source of novel antimicrobial metabolites. Further, the antimicrobial metabolites were extracted from the isolate using ethyl acetate solvents and the antimicrobial efficacies were screened by chemical analysis and tested against bacterial pathogens. The metabolites of isolate showed maximum zone of inhibition against all the pathogens viz., Pseudomonas aeruginosa, Escherichia coli, Klebsilla pneumoniae, Bacillus cereus and Staphylococcus aureus as 21 ± 0.12, 20 ± 0.42, 21 ± 1.2, 16 ± 2.01, 15 ± 0.47 respectively. The marine samples which displayed antibacterial activity of actinomycetes may be useful in the clinical conditions where higher secondary metabolites against antibiotic resistant bacteria.

Signalling crosstalk in light stress and immune reactions in plants

The evolutionary history of plants is tightly connected with the evolution of microbial pathogens and herbivores, which use photosynthetic end products as a source of life. In these interactions, plants, as the stationary party, have evolved sophisticated mechanisms to sense, signal and respond to the presence of external stress agents. Chloroplasts are metabolically versatile organelles that carry out fundamental functions in determining appropriate immune reactions in plants. Besides photosynthesis, chloroplasts host key steps in the biosynthesis of amino acids, stress hormones and secondary metabolites, which have a great impact on resistance against pathogens and insect herbivores. Changes in chloroplast redox signalling pathways and reactive oxygen species metabolism also mediate local and systemic signals, which modulate plant resistance to light stress and disease. Moreover, interplay among chloroplastic signalling networks and plasma membrane receptor kinases is emerging as a key mechanism that modulates stress responses in plants. This review highlights the central role of chloroplasts in the signalling crosstalk that essentially determines the outcome of plant-pathogen interactions in plants.

Evolutionary Biology: A Basic Science for Medicine in the 21st Century

Evolutionary biology was a poorly developed discipline at the time of the Flexner Report and was not included in Flexner's recommendations for premedical or medical education. Since that time, however, the value of an evolutionary approach to medicine has become increasingly recognized. There are several ways in which an evolutionary perspective can enrich medical education and improve medical practice. Evolutionary considerations rationalize our continued susceptibility or vulnerability to disease; they call attention to the idea that the signs and symptoms of disease may be adaptations that prevent or limit the severity of disease; they help us understand the ways in which our interventions may affect the evolution of microbial pathogens and of cancer cells; and they provide a framework for thinking about population variation and risk factors for disease. Evolutionary biology should become a foundational science for the medical education of the future.

Linking questions to practices in the study of microbial pathogens: Sampling bias and typing methods

The importance of understanding the population genetics and evolution of microbial pathogens is increasing as a result of the spread and re-emergence of many infectious diseases and their impact for public health. In the last few years, the development of high throughput multi-gene sequence methodologies has opened new opportunities for studying pathogen populations, providing reliable and robust means for both epidemiological and evolutionary investigations. For instance, for many pathogens, multilocus sequence typing has become the “gold standard” in molecular epidemiology, allowing strain identification and discovery. However, there is a huge gap between typing a clinical collection of isolates and making inferences about their evolutionary history and population genetics. Critical issues for studying microbial pathogens such as an adequate sampling design and the appropriate selection of the genetic technique are also required, and will rely on the scale of study and the characteristics of the biological system (e.g., multi- vs. single-host pathogens and vector vs. food or air-borne pathogens). My aim here is to discuss some of these issues in more detail and illustrate how these aspects are often overlooked and easily neglected in the field. Finally, given the rapid accumulation of complete genome sequences and the increasing effort on microbiology research, it is clear that now more than ever integrative approaches bringing together epidemiology and evolutionary biology are needed for understanding the diversity of microbial pathogens.

:Evolution of Microbial Pathogens

:Evolution of Microbial Pathogens

Evolution of Microbial Pathogens

This book is one of the first to provide an up-to-date view on a fundamental issue in medical microbiology research: how the accumulated genetic and genomic information is contributing to our understanding of virulence factors and the evolution of virulence in microbial pathogens. The editors should be commended for assembling 35 outstanding contributors, who specialize in various areas of microbial pathogenesis and evolution. The 14 chapters are grouped into 3 broad sections: general concepts in microbial evolution, environment and the evolution of microbial pathogens, and the evolution of selected pathogenic species and mechanisms. At the beginning of each section, a concise overview of individual chapters integrates the content of the chapters into the section. In the first section, the 5 chapters introduce the basic processes affecting microbial evolution, from the individual molecular level to the genomic, cellular, and population levels. Well-known concepts such as horizontal (lateral) gene transfer, the relationship between virulence and transmission, and pathogenicity islands are discussed extensively. Of special note are 2 chapters that are often missing in traditional medical microbiology books: 1 describes how long-term experimental evolutionary studies in the laboratory can contribute to our understanding of microbial pathogen evolution in the environment and clinics, and the other describes how gene inactivation and gene loss can be creative forces during the evolution of many microorganisms, especially obligate intracellular pathogens. In the second section, the 5 chapters review how interactions between microbes and various natural biotic and abiotic factors can influence the origin and evolution of virulence in microbial pathogens. These factors are the physical, chemical, and biologic properties of the soil environment; the plant and animal environments; and to a lesser extent, the aquatic and atmospheric environments. Other highly topical issues are the evolutions of toxins, secretion systems, and antibiotic resistance. In the third section, the 4 chapters extensively discuss the evolution of selected groups of microbial pathogens: group A Streptococcus and Staphylococcus aureus; enteric pathogens such as Escherichia coli, Salmonella enterica, and Yersinia spp.; Mycobacterium spp.; and fungal pathogens such as Candida albicans and Cryptococcus neoformans. The authors provide rich detail of molecular variation within and between populations of these species and describe how patterns of population genetic variation have contributed to our understanding of the evolution of virulence and virulence factors in these pathogens. I have no major criticism of what is included in this book; rather, I note what is absent, which could have made the book more comprehensive. The first is an overall evolutionary framework of the distribution of microbial pathogens on the phylogenetic tree. Such a macro-evolutionary framework would showcase the nonrandom patterns of the distribution of human pathogens among major phylogenetic groups of microorganisms. Second, although base substitutions, insertions and deletions, homologous recombination, and lateral gene transfer are discussed throughout the book, a generalized quantitative review of the relative contributions of these processes during the evolution of certain groups of microbial pathogens (e.g., E. coli) would have been highly informative. These processes are fundamental to the evolution of all groups of organisms, and the analysis of the unparalleled datasets in microbial pathogens can teach us much about the evolution of other groups of organisms. Third, although many human pathogens are globally distributed, a substantial number show geographic specificity and endemism. Therefore, the spatial and temporal patterns of distribution of microbial pathogens within a species and at the species level across the globe are highly relevant to the evolution of microbial pathogens. Lastly, this book is highly biased toward bacterial pathogens. Only 1 chapter deals with nonbacterial (fungal) pathogens, and no chapter discusses viral or protozoan pathogens, which are responsible for some of our biggest public health threats, e.g., HIV, influenza A, and Plasmodium falciparum. Nevertheless, this is a timely and much-needed book about the evolution of bacterial virulence and its pathogenesis. It will be a valuable resource for researchers in the field of microbial evolution and pathogenesis, senior undergraduate students, graduate students, faculty who teach medical microbiology and microbial evolution, clinical microbiologists, and infectious disease specialists.