Contact : Michael DUBOW
Phone : 01 69 15 46 12
Email : michael.dubow(AT)igmors.u-psud.fr
Michael DUBOW, Professor, University of Paris-Sud 11
Solange BERTRANDY, Lecturer, University of Paris-Sud 11
Loïc MORIN, Lecturer, University of Paris-Sud 11
Christophe REGEARD, Lecturer, University of Paris-Sud 11
Simone SEROR, Senior Scientist Emeritus
Barry Holland, Senior Scientist voluntary
Micheline TERRIER, Technician CNRS
Nga NGUYEN THI TUYET, Ph. D. student
Jorge OSMAN NAOUM, Ph. D. student
Yang WANG, Ph. D. student
Protist Diversity managed by Loïc MORIN, Lecturer, University of Paris-Sud 11
Molecular analysis of swarming communities in Bacillus subtilis by Simone SEROR
Protein secretion (ABC transporter) and the role of Ca2+ in E. coli, I Barry HOLLAND
Approaches based on 16S rDNA sequences have demonstrated that fewer than five percent of the microbes on Earth have been cultivated and studied. Furthermore, it has been shown that the majority of these different microbes live in communities attached to surfaces, called biofilms, consisting of prokaryotes and eukaryotes fastened to a solid surface and surrounded by exopolysaccharide.
Finally, the fact that most known organisms are infected by more than one type of virus or bacteriophage (according to the cell which they infect) strongly suggests that the viruses of prokaryotes represent the most diverse form of life on Earth and also themost unknown. This unexplored biological realm is now capable of examination at the molecular level. The purpose of the research program of the group, "Genomics and Microbial Biodiversity of Biofilms" is to identify these phages (and their genes) that play a role in microbial growth and development in natural environments so that we can begin to dissect and exploit their functions.
We have determined the presence of bacteriophages in the Sahara Desert and showed that there exists a variety of phage morphotypes when examined by electron microscopy and by whole genome analysis on Pulsed-field gels (Prigent et al. Extremophiles). We are commencing a functional study of these phage genomes to search for candidate phage genes that affect the capacity of E. coli and P. aeruginosa to form biofilms, as well as for other interesting and useful genes (e.g. resistance to dessication, etc.) as well as begin to sequence the genomes of the most abundant phages.
We have begun to screen for phage genes which can modify the life of bacteria using a functional genomics approach (Liu et al, 2004). We prepared a library of bacteriophage D108 DNA cloned in a plasmid vector and transformed into E. coli and subsequently screened for their capacity to grow on solid media and to form biofilms in microtiter plates. We found 21 bacterial clones affected in one or several of their growth properties. The majority of the clones were found to display altered colony morphology when grown on semi-solid media and more than half showed altered biofilm characteristics. Following identification of the specific bactériophage D108 open reading frame(s) responsible for these effects, we will search for their cellular target and their mechanism(s) of action. This research platform will be extrapolated to other known phages, as well those that we isolate from a variety of natural environments.
Keywords: Bacteriophages, biofilms, environment, electronic microscopy, functional genomics, metagenomics, microbial molecular physiology.
Poitelon JB, Joyeux M, Welte B, Duguet JP, Prestel E and DuBow MS, (2010), Variations of bacterial 16S rDNA phylotypes prior to and after chlorination for drinking water production from two surface water treatment plants, J Ind Microbiol Biotechnol, 37(2):117-28
Deschavanne P, Dubow MS and Regeard C, (2010), The use of genomic signature distance between bacteriophages and their hosts displays evolutionary relationships and phage growth cycle determination, Virol J, 7(1):163
Poitelon JB, Joyeux M, Welte B, Duguet JP, Peplies J and DuBow MS, (2009), Identification and phylogeny of eukaryotic 18S rDNA phylotypes detected in chlorinated finished drinking water samples from three Parisian surface water treatment plants, Lett Appl Microbiol 49(5): 589-95
Poitelon JB, Joyeux M, Welte B, Duguet JP, Prestel E, Lespinet O and DuBow MS, (2009), Assessment of phylogenetic diversity of bacterial microflora in drinking water using serial analysis of ribosomal sequence tags, Water Res 43(17): 4197-206
Gueuné H, Durand MJ, Thouand G, Dubow MS, (2008), The ygaVP Genes of Escherichia coli Form a Tributyltin-inducible Operon, Appl Environ Microbiol. 74(6): 1954-1958
Leroy M, Prigent M, Dutertre M, Confalonieri F and DuBow M, (2008), Bacteriophage morphotype and genome diversity in Seine River sediment, Freshwater Biology 53: 1176-1185
Li T, Wu TD, Mazeas L, Toffin L, Guerquin-Kern JL, Leblon G and Bouchez T, (2008), Simultaneous analysis of microbial identity and function using NanoSIMS, Environ Microbiol 10(3): 580-8