Home  About us  Contact
 

Microbial World (microbial + world)

Distribution by Scientific Domains
Life Sciences40%
Chemistry40%

Selected Abstracts

Systems Biology in the Microbial World and Beyond

CHEMISTRY & BIODIVERSITY, Issue 5 2010
Zhongming Zhao
First page of article [source]

Microbial diversity , insights from population genetics

ENVIRONMENTAL MICROBIOLOGY, Issue 1 2008
Ted H. M. Mes
Summary Although many environmental microbial populations are large and genetically diverse, both the level of diversity and the extent to which it is ecologically relevant remain enigmatic. Because the effective (or long-term) population size, Ne, is one of the parameters that determines population genetic diversity, tests and simulations that assume selectively neutral mutations may help to identify the processes that have shaped microbial diversity. Using ecologically important genes, tests of selective neutrality suggest that adaptive as well as non-adaptive types of selection act and that departure from neutrality may be widespread or restricted to small groups of genotypes. Population genetic simulations using population sizes between 103 and 107 suggest extremely high levels of microbial diversity in environments that sustain large populations. However, census and effective population sizes may differ considerably, and because we know nothing of the evolutionary history of environmental microbial populations, we also have no idea what Ne of environmental populations is. On the one hand, this reflects our ignorance of the microbial world. On the other hand, the tests and simulations illustrate interactions between microbial diversity and microbial population genetics that should inform our thinking in microbial ecology. Because of the different views on microbial diversity across these disciplines, such interactions are crucial if we are to understand the role of genes in microbial communities. [source]

The Versatility of Helicobacter pylori CagA Effector Protein Functions: The Master Key Hypothesis

HELICOBACTER, Issue 3 2010
Steffen Backert
Abstract Several bacterial pathogens inject virulence proteins into host target cells that are substrates of eukaryotic tyrosine kinases. One of the key examples is the Helicobacter pylori CagA effector protein which is translocated by a type-IV secretion system. Injected CagA becomes tyrosine-phosphorylated on EPIYA sequence motifs by Src and Abl family kinases. CagA then binds to and activates/inactivates multiple signaling proteins in a phosphorylation-dependent and phosphorylation-independent manner. A recent proteomic screen systematically identified eukaryotic binding partners of the EPIYA phosphorylation sites of CagA and similar sites in other bacterial effectors by high-resolution mass spectrometry. Individual phosphorylation sites recruited a surprisingly high number of interaction partners suggesting that each phosphorylation site can interfere with many downstream pathways. We now count 20 reported cellular binding partners of CagA, which represents the highest quantitiy among all yet known virulence-associated effector proteins in the microbial world. This complexity generates a highly remarkable and puzzling scenario. In addition, the first crystal structure of CagA provided us with new information on the function of this important virulence determinant. Here we review the recent advances in characterizing the multiple binding signaling activities of CagA. Injected CagA can act as a ,master key' that evolved the ability to highjack multiple host cell signalling cascades, which include the induction of membrane dynamics, actin-cytoskeletal rearrangements and the disruption of cell-to-cell junctions as well as proliferative, pro-inflammatory and anti-apoptotic nuclear responses. The discovery that different pathogens use this common strategy to subvert host cell functions suggests that more examples will emerge soon. [source]

Zymomonas mobilis: an alternative ethanol producer

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2006
Parmjit S Panesar
Abstract Zymomonas mobilis is a unique bacterium in the microbial world, and offers a number of advantages over the existing ethanol-producing microorganisms. Being a prokaryote, it is more amenable to genetic manipulations. Thus, it has attracted great attention in the ethanol production world and efforts have been made to commercialize its application for the purpose. Despite the various efforts made worldwide, none of the processes using this microbe has been commercialized owing to certain bottlenecks. To circumvent the hindrances currently associated with a Zymomonas process, researchers have made various attempts to improve the technology using different techniques. This paper reviews the different substrates and the genetic improvement techniques with special emphasis on mutagenesis and recombinant DNA technology used for ethanol production by Zymomonas strains. Copyright © 2006 Society of Chemical Industry [source]

A microbial world within us

MOLECULAR MICROBIOLOGY, Issue 6 2006
Erwin G. Zoetendal
Summary The microbial world within us includes a vast array of gastrointestinal (GI) tract communities that play an important role in health and disease. Significant progress has been made in recent years in describing the intestinal microbial composition based on the application of 16S ribosomal RNA (rRNA)-based approaches. These were not only instrumental in providing a phylogenetic framework of the more than 1000 different intestinal species but also illustrated the temporal and spatial diversity of the microbial GI tract composition that is host-specific and affected by the genotype. However, our knowledge of the molecular and cellular bases of host,microbe interactions in the GI tract is still very limited. Here an overview is presented of the most recent developments and applications of novel culture-independent approaches that promise to unravel the mechanisms of GI tract functionality and subsequent possibilities to exploit specifically these mechanisms in order to improve gut health. [source]