Dr. Louis S. Tisa

Associate Professor

Department of Microbiology

Member of the Genetics Program

Ph.D., University of Wisconsin, 1987

STATEMENT OF MY RESEARCH INTERESTS

My research interests are in microbial physiology and diversity and the impact that they have on the environment. This interest also includes the general areas of Biology of the Actinomycetes; Signal Transduction; Bioremediation; Environmental Genomics; Insect-Microbe Interactions; Plant-Microbe Interactions.

My research program is divided into several areas.

(1) Molecular and cellular aspects of the developmental biology of the actinomycetales. Several different aspects of the biology of actinomycetales are of interest to me at both the cellular and molecular level. These prokaryotes exhibit a wide diversity in morphology, physiology and habitat. The production of antibiotics and other secondary metabolites along with their complex developmental life cycle make these organisms attractive to study. Current work is focused on the molecular biology of Frankia. These bacteria are nitrogen-fixing actinomycetes (gram-positive filamentous bacteria) that form a symbiotic association with over 200 different species of plants belonging to eight different plant families, which are only distantly related to each other. These actinorhizal plants are an important part of the nitrogen budget of the planet and are of potential economic significance. My studies have concentrated on the physiology, biochemistry, and genetics of the microorganism. We are developing genetic tools that are necessary for the establishment of a genetic transfer system with Frankia. In a collaborative project with UCONN and JGI, we sequenced the complete genome of Frankia and in collaboration with the UNH CSB we have initiated proteomics studies on this system. Two Frankia strains, CcI3 and EAN1pec, representing two of the three major lineages within the genus were sequenced. The host compatibilities of these two strains differ greatly. Strain CcI3 is restricted to Casuarina and Allocasuarina sp., while the host range of strain EAN1pec is more diverse. Despite having 16S rRNA sequences that are 98% identical, two genomes differed greatly in size. The genome of Frankia CcI3, a strain that infects only Casuarina sp., is 5.5Mb encoding 4841 putative ORFs. Frankia strain EAN1pec, a broad host-range strain that infects plants from three families, has a genome size of 9.1Mb with a total of 7993 putative ORFs. These data on these two Frankia genomes are available at the following websites: http://genome.ornl.gov/microbial/fran_cci3/ and http://genome.ornl.gov/microbial/fran_ean1/. Currently, in collaboration with several groups world-wide, we are leading the efforts to sequence five more Frankia strains representing diverse habitats and environments.

The availability of these three Frankia genome sequences has provided significant background information for further genetic approaches and gene expression studies including proteomics and transcriptome analysis. Thus, the time is right to initiate functional genomic and proteomic studies on this bacterial system. Our future efforts are directed toward functional genomics of Frankia to help our understanding of the actinorhizal symbiosis. We have started to use of power of proteomics and genomics to study Frankia physiology, developmental biology, and its interactions with its host plants. We have initially focused on the use of proteomic tools including 2-dimensional gel electrophoresis and MALDI-TOF to identify vesicle-specific proteins and novel proteins involved in actinorhizal nitrogen fixation. We want also correlate the Frankia proteomics results with gene expression studies. During the past decade there has been radical change in our approach to gene expression. Genomes from many different organisms have been or are being sequenced. This wealth of knowledge has lead to development of new technologies to study gene expression. We are now capable of exploring global gene expression. The development of DNA array technologies has allowed us to investigate the expression of large numbers of genes. With the completion of three Frankia genome sequences, we are beginning a pilot project to explore the Frankia transcriptome. We are developing a high-density DNA microarray for the Frankia CcI3 genome which will be used to identify Frankia global gene expression pattern. These transcriptome studies will be validated by Real Time RT-PCR experiments. Lastly, we are continuing to establish an insertional mutagenesis system for Frankia. Several genetic markers for Frankia strains have been identified that provide a mechanism for positive selection. Our strategy focuses on the cloning of these native resistance markers and their introduction into cloned Frankia target genes via cassette-mutagenesis or in vitro transposition. These powerful genomic tools will be useful to help increase our understanding of the nature of the Frankia-actinorhizal nodule symbiotic relationship.

(2) Signal Transduction in Symbiosis and Pathogenesis. The use of microbe-insect and microbe-nematode interactions as model systems to study pathogenesis has been increasing rapidly. These low costs model systems are ethically attractive compared to the use of mammalian systems and may provide evolutionary implications for diseases because of the age of invertebrate lineages. We are currently studying microbe-nematode interactions specifically the Photorhabdus - entomopathogenic nematodes (Heterorhabditis) association, which is useful biological control agent for several insect pest. We are interested in understanding the roles that bacterial motility, biofilm formation and signal transduction play in the life cycle of Photorhabdus spp. This bacterium is a symbiont of nematodes and an insect pathogen and is also an excellent model system to understand the ability of an organism to switch from symbiotic state to pathogenic state. These bacteria produce antibiotics and insecticides and they also show great potential as a biological control agent. Besides production of antibiotics and toxins, the bacteria also generate essential growth factors for the nematode. Nematode development and reproduction requires the bacteria which are specific for each nematode species. Thus, the bacteria create an optimum environment in the insect cadaver for nematode reproduction and development, and the eventual release of infective juveniles. These bacteria are motile by swimming and swarming. Cells use signal transduction to monitor changes in their environment and make the necessary responses to these changes. For example, the signal transduction process influences and controls the development of cell motility and surface-associated growth (termed biofilms). Motility and biofilm formation also play a significant role in the life cycles of both symbiotic and pathogenic bacteria. Current studies have centered on a molecular genetic approach to understand the role of signal transduction and motility in symbiosis, pathogenesis and the switch between these two life stages.

Besides the nematode-associated-forms, human infections with Photorhabdus spp. have been reported in the USA and Australia . While the route of infection was unknown, the clinical isolates of Photorhabdus from these human infections are homogenous and form a species that is distinct from the nematode-symbiotic Photorhabdus. The identification of clinical isolates suggests that Photorhabdus might be a new emerging human pathogen. We have also been investigating these isolates

We are looking at other potential model systems including a Serratia-C.briggsae association. In collaboration with Kelley Thomas (UNH) and Vaughn Cooper (UNH), we are investigating an unknown Serratia strain that we have learned can form a symbiosis with Caenorhabditis nematodes, including C. elegans. Like the Photorhabdus/Heterorhabditis system, this bacterial-nematode symbiosis is a potent insect pathogen and potential biological control agent. Studying this interaction is especially promising because of the wealth of information about the nematode host and the genomes of two other insect- and human-pathogenic Serratia strains are available.

(3) Bioremediation and microbial interaction with heavy metals. Toxic metals and organic contaminants pose a significant environmental problem that impacts human health. My lab has a strong interest in the use of microorganisms to clean up these environments termed bioremediation. My research group is associated with the Bedrock Bioremediation Center (BBC) http://www.unh.edu/erg/bbc/index.html, which is a new center situated within the Environmental Research Group at the University of New Hampshire. It specializes in multidisciplinary research on bioremediation of organically-contaminated bedrock aquifers including developing improved methods of site characterization, new engineering technologies to improve the success of bioremediation in situ, and new laboratory procedures to estimate the rate of in situ biodegradation.

Toxic heavy metals and metalloids pose a significant environmental problem that impacts human health. While organic contaminants can be degraded completely, toxic metals and metalloids are persistent and only change their elemental state. This persistence has rendered these heavy-metal-contaminated environments as unusable for extended periods of time. There is a clear need to clean up these environments. Physical methods such as the removal of contaminated soil from a site and its burial elsewhere are environmentally destructive. The high costs and the sometimes-limited effectiveness of these conventional remediation technologies have stimulated interest in bioremediation, including phytoremediation, as an alternative clean-up method. Actinorhizal plants provide an excellent mechanism to restore disrupted environmental sites. Actinorhizal plants have been successfully used to recolonize and reclaim land that has been industrial wasteland including lands spoiled by metaliferous mine spoils and smelter waste. Although the use of actinorhizal plants for land reclamation of industrial wasteland is well know, the mechanisms of how they function in this role have not been investigated.

We have been investigating the physiology and the genetics of Frankia and are establishing genomic and genetic tools for this bacterial system to exploit their potential to provide renewable resources for fuel and restore previously disrupted environments. This project is the result of these studies and our interest in heavy metals and bioremediation. Our results indicate that Frankia is resistant to elevated levels of heavy metals. Their mechanisms of resistance are unknown, but our preliminary results suggest that detoxification of a metal and that Frankia has the ability to bind and sequester several toxic heavy metals. These results indicate that Frankia has potential remediation and phytoremediation applications.

From our survey of heavy metal sensitivities, the following five possible metal resistance traits were identified as potential candidates for further study: arsenate, copper, lead, chromate and selenite. Selenite resistance appears to involve detoxification by the reduction of the oxyanion selenite (clear) to elemental selenium (red precipitate). We have some preliminary lines of evidence which suggest that resistance to Cu +2 and Pb +2 may involve the binding and sequestering of the heavy metal. Since Frankia is resistant only to arsenate and is sensitive to arsenite and antimony, we would predict that this resistance is caused by an alteration of the phosphate transport system. Some Streptomyces species acquire resistance by that mechanism. Based on our preliminary results we would also predict that chromate resistance occurs by an efflux mechanism and not by a chromate reduction. Chromate efflux systems have been identified in several bacterial systems.

We are interest in identifying the components that involved in Pb 2+, Cu 2+ and SeO 3 -2 resistance. One approach would use proteomic tools to identify specific proteins or gene products that are involved heavy metal resistance. We are also interested in understanding the molecular and biochemical mechanisms of the resistance traits.

Funding:

Support for the research in my lab is currently or has been funded by the following sources: American Heart Association, EPA, NSF, NIH, USDA CREES, USDA Hatch and other outside contracts.

Representative Reprints (post 2002):

Richards, J.W., G.D. Krumholz, M.S. Chval, and L.S. Tisa. 2002. Heavy metal resistance patterns of Frankia strains. Appl. Environ. Microbiol. 68:923-927.
Turick, C.E., L.S. Tisa, and F. Caccavo. 2002. Melanin production and use as a soluble electron shuttle for Fe(III) oxide reduction and as a terminal electron acceptor by Shewanella algae BrY. Appl. Environ. Microbiol. 68:2436-2444.
Beckwith, J., J.D. Tjepkema, R.E. Cashon, C.R. Schwintzer, and L.S. Tisa 2002. Hemoglobin in five genetically diverse Frankia strains. Can. J. Microbiol.48:1048-1055
Myers, A., T. Rawnsley, and L.S. Tisa. 2002. Developing genetic tools for Frankia, the bacterial partner of the actinorhizal symbiosis. In: Finn, T.M., M.R. O'Brian, D.B. Layzell, J.K. Vessey, and W. Newton (eds.) Nitrogen Fixation: Global Perspectives. CAB International, p. 385.
Turick, C.E., F. Caccavo Jr., and L.S. Tisa. 2003. Electron transfer from Shewanella aglae BrY to hydrous ferric oxide is mediated by cell-associated melanin. FEMS Microbiol. Letts. 220:99-104
Hogdson, M., B. Day, D.J. White, and L.S. Tisa. 2003. Effect of growth conditions on the motility of Photorhabdus. Arch. Microbiol. 180:17-24.
Krumholz, G., M. Chval, M.J. McBride, and L.S. Tisa. 2003. Germination and physiological properties of Frankia spores. Plant Soil 254:57-67.
Myers, A. K. and L.S. Tisa. 2003. Effect of electroporation conditions on cell viability of Frankia EuI1c. Plant Soil 254:83-88.
Myers, A. and L.S. Tisa. 2004. Isolation and Characterization of Antibiotic-Resistant and Antimetabolite-Resistant Mutants of Frankia strains EuI1c and CcI.17. Can J. Microbiol. 50:261-267.
Tisa, L.S. and J. Richards. 2004. Metabolic capacity of vesicles of Frankia strain EAN1pec. Symbiosis 37: 365-378
Delbridge, L., Coulburn, W. Fagerberg, and L.S. Tisa. 2004. Community profiling of bacterial endosymbionts in four species of Caulerpa. Symbiosis 37: 335-344
Kinner, N. E; T.T. Eighmy, M. Mills, J. Coulburn, and L. Tisa. 2005. Microbial processes in fractured rock environments. In: Faybishenko, B., P.A. Witherspoon, and J. Gale (eds.) "Dynamics of fluids and transport in fractured rock" Geophysical Monograph, vol.162, pp.183-193.
Niemann, J.M., J. Tjepkema, and L.S. Tisa. 2005. Identification of the Truncated Hemoglobin Gene in Frankia sp. Symbiosis 39:91-95.
Eighmy, T.T., J.C.M. Spear, J. Case, H. Marbet, J. Casas, W. Bothner, J. Coulburn, L. S. Tisa, M. Majko, E. Sullivan, M. Mills, K. Newman, and N. E. Kinner. 2007. Role of Microfracture Surface Geochemistry in Adherent Microbial Population Metabolism in TCE-Contaminated Competent Bedrock. Geomicrobiol. J. 24:307-330.
Normand, P., P. Lapierre ,L. S. Tisa, N Alloisio, B Cournoyer, C. Lavire, J. Marechal, P. Pujic, J. P. Gogarten, Y. Huang, J. Mastronunzio, D. Bickhard, C. Bassi, T. Rawnsley, J. Niemann, M. P. Francino, A. Lapidus, M. Martinez, E. Goltsman, G. Perriere, C. Medigue, N. Choisne, A Couloux, S. Cruveiller, L. Labarre, Z. Rouy, D. Vallenet, C. T. Cong Y, N. Demange, B. Mullin, O. Kopp, Y. Wang, J. Tomkins, A. Berry, A. Sellstedt, F. Tavares, C. Valverde, L. Wall, and D. R. Benson. 2007. Genome characteristics of three facultatively symbiotic Frankia sp. strains reflect host range and host plant biogeography. Genome Research 17:7-15
Rawnsley, T. and L.S. Tisa. 2007. Development of a physical map for three Frankia strains and a partial genetic map for Frankia EuI1c. Physiologia Plantarum 130:427-439
Normand P, C. Queriroux, L.S. Tisa, D.R. Benson, Z. Rouy, and C. Médique. 2007 Exploring the Genomes of Frankia. Physiologia Plantarum 130:331-343
Tisa , L.S., D.R Benson, G.B. Smejkal, P. Lapierre, J. P. Gogarten, P. Normand, M. P. Francino, and P. Richardson Living large: Elucidation of the Frankia EAN1pec genome sequence shows gene expansion and metabolic versatility. In F. Dakora, W. E. Newton, C. Elmerich, V Newton (eds) Proceeding of the 15 th International Congress on Nitrogen Fixation..p.
Sen, G., S. Sur, D. Bose, U. Mondal, T. Furnholm, A. Bothra, L.S. Tisa, and A. Sen. 2007. Analysis of codon usage patterns and predicted highly expressed genes for six phytopathogenic Xanthomonas genomes shows a high degree of conservation. In Silico Biology 7, 0039 (2007).

Recent Abstracts (post 2002):

Rawnsley, T. and L.S. Tisa. 2002. Construction of a Physical Map of Frankia Chromosome. Abstr.H-123, p.243. In Abstracts of the 102st General Meeting of the American Society for Microbiology 2002. ASM, Washington, D.C. ( Salt Lake City, UT).
Tisa, L.S., W. Naser, J. Coulburn, E. Sullivan, A. Mumford, S. G. Acinas, M. Mills, K. Newman, and N.E. Kinner. 2002. Community Profiling of TCE-Contaminated Saturated Bedrock. Abstr. 2002 International Symposium on Surface Microbiology. Copenhagen, Denmark September 2002.
Eighmy, T.T., J.C.M. Spear, W. Naser, J. Coulburn, L.S. Tisa, W. Bothner, A. Munford, E. Sullivan, M. Mills, K. Newman and N.E. Kinner. 2002. Preliminary spectroscopic and microbial investigations on microfracture surfaces from TCE-contaminated Kittery formation bedrock from the Bedrock Bioremediation Center study site. Abstr. 2002 International Symposium on Surface Microbiology. Copenhagen, Denmark September 2002.
Griffths, E., N.E. Kinner, L. Delbridge, A. Mumford, W. Naser, and L.S. Tisa. 2002. Microbial Tracer Studies During Drilling in Saturated Bedrock. Abstr. 2002 International Symposium on Surface Microbiology. Copenhagen, Denmark September 2002. Day, B., M. Hodgson, and L.S. Tisa. 2003. Isolation and Characterization of Photorhabdus luminescens Motility Mutants. Abstr.I-52, p.339. In Abstracts of the 103rd General Meeting of the American Society for Microbiology 2003. ASM, Washington, D.C. ( Washington, DC).
Coulburn, J., T. T. Eighmy, J. Spear, W. Bothner, M. Mills, N. E. Kinner , and L. S. Tisa. 2003. Community Profiling and Spectroscopic Analyses of Partially Mineralized Sealed Fractures in Trichloroethylene-Contaminated Kittery Formation Bedrock. Abstr.N-158, p.426. In Abstracts of the 103rd General Meeting of the American Society for Microbiology 2003. ASM, Washington, D.C. ( Washington, DC).
Rawnsley, T., A. Myers, and L.S. Tisa. 2003. Transposon Mutagenesis of Frankia. Abstr.N-226, p.438. In Abstracts of the 103rd General Meeting of the American Society for Microbiology 2003. ASM, Washington, D.C. ( Washington, DC).
Delbridge, L., Coulburn, W. Fagerberg, and L.S. Tisa. 2003. Identification of possible bacterial endosymbionts in four species of Caulerpa from two different habitats. 4th International Symbiosis Society Congress Halifax, NS
Tisa, L.S, T. Rawnsley, A. Myers and J. Niemann. 2003. Transposon Mutagenesis of Frankia, the Bacterial Partner of the Actinorhizal Symbiosis. August17-23, 2003, 4th International Symbiosis Society Congress Halifax, NS Canada
Day, B., E Janicki, R. Jackobek, M. Hodgson, and L S. Tisa. 2003. Isolation and Characterization of Photorhabdus temperata Motility Mutants. September 3-7, 2003, 3rd International Symposium on Entomopathogenic Nematodes and Symbiotic Bacteria, Wooster, OH.
Arif, M and L.S. Tisa.2004. Global Gene Expression Profile of Escherichia coli Genome in Response to Calcium. Abstr.H-77, In Abstracts of the 104th General Meeting of the American Society for Microbiology 2003. ASM, Washington, D.C. ( New Orleans, LA).
Janicki, E, B. Day, and L.S. Tisa. 2004. Isolation and Characterization of Photorhabdus temperata Mutants Defective in Biofilm Formation. Abstr.I-43, In Abstracts of the 104th General Meeting of the American Society for Microbiology 2003. ASM, Washington, D.C. ( New Orleans, LA).
Day, B., R. Jackobek, E. Janicki, and L.S. Tisa. 2004. Identification of Photorhabdus temperata Motility Mutants and Their Physiological Properties. Abstr.I-042, In Abstracts of the 104th General Meeting of the American Society for Microbiology 2003. ASM, Washington, D.C. ( New Orleans, LA).
Coulburn, J., L. Delbridge, W. Fagerberg, L.S. Tisa. 2004. Community Profiles of Possible Bacterial Endosymbionts in Four Species of Caulerpa. Abstr. I-39, In Abstracts of the 104th General Meeting of the American Society for Microbiology 2003. ASM, Washington, D.C. ( New Orleans, LA).
Rawnsley, T. and L. S. Tisa. 2004. Construction of a Physical Map for three Frankia isolates: CcI3, EuI1c and EAN1pec. August1-4, 2004, The 13th International Conference on Frankia and Actinorhizal Plants Durham, NH.
Niemann, J.M., J. Tjepkema, and L.S. Tisa. 2004. Identification and Expression of the Truncated Hemoglobin Gene of Frankia Isolate EAN1pec. August1-4, 2004, The 13th International Conference on Frankia and Actinorhizal Plants Durham, NH.
Eighamy, T., J. Spear, W. Bothner, J. Coulburn, L. Tisa and N. Kinner. 2004. Microfracture geochemistry as an indicator of terminal electron accepting process in TCE-contaminated bedrock. EPA/NWGA Fractured Rock Conference. (September 13-15 Portland, ME).
Kinner, N.E., M.Mills, T. Eighamy, T. Ballestro, J. Coulburn, L. Tisa, and S. Druschel. 2004. Effectiveness of Monitored Natural Attentuation at Predicting In Situ biodegradation in a TCE contaminated Metasedimentary bedrock. EPA/NWGA Fractured Rock Conference. (September 13-15 Portland, ME).
Rawnsley, T., A. Myers and Tisa, L.S. 2004. Transposon Mutagenesis of Frankia, the Bacterial Partner of the Actinorhizal Symbiosis. August1-4, 2004, The 13th International Conference on Frankia and Actinorhizal Plants Durham, NH.
Tisa, L.S., D. R Benson, M. P. Francino, and Paul Richardson. 2004. Comparative Genomics of Two Frankia Strains: From the Restrictive to the Promiscuous. Invited Speaker to the14th International Congress on Biological Nitrogen Fixation in Beijing, China Oct 27th to Nov1, 2004
Eighamy, T., J. Spear, W. Bothner, J. Coulburn, L. Tisa and N. Kinner. 2004. Microfracture geochemistry as an indicator of terminal electron accepting process in TCE-contaminated bedrock. EPA/NWGA Fractured Rock Conference. (September 13-15 Portland, ME).
Kinner, N.E., M.Mills, T. Eighamy, T. Ballestro, J. Coulburn, L. Tisa, and S. Druschel. 2004. Effectiveness of Monitored Natural Attentuation at Predicting In Situ biodegradation in a TCE contaminated Metasedimentary bedrock. EPA/NWGA Fractured Rock Conference. (September 13-15 Portland, ME).
Lapierre P., J.P. Gogarten, Y. Huang, J. Mastronunzio, T. Rawnsley, C. A. Bassi, L. S. Tisa, and D. R. Benson. 2005. Comparative analysis of two sequenced Frankia sp., genome plasticity and insight on their symbiosis interaction with actinorhizal host plants. International Conference on Microbial Genomes, Halifax, NS Canada
Michaels, B.A. and L.S. Tisa. 2005. Swarming Motility by Photorhabdus temperata and the Isolation of Hyperswarming Mutants. Abstr.I-81, In Abstracts of the 105 th General Meeting of the American Society for Microbiology 2005. ASM, Washington, D.C. ( Atlanta, GA).
Niemann, J. M., J.D. Tjepkema, D.R. Benson, and L.S. Tisa. 2005. Effect of Environmental Stimuli on the Expression of Truncated Hemogloblin in Frankia. Abstr. I-47, In Abstracts of the 105 th General Meeting of the American Society for Microbiology 2005. ASM, Washington, D.C. ( Atlanta, GA)
Benson, D.R., L.S. Tisa, J. Gogarten, P. Lapiere, M. Francino, Y. Haung, T. Rawnsley, and C. Bassi. 2005. Comparison of the Genome Sequences from Frankia CcI3 and EAN1pec, Actinobacteria from the Frankiaceae. Abstr.N-195, In Abstracts of the 105 th General Meeting of the American Society for Microbiology 2005. ASM, Washington, D.C. ( Atlanta, GA)
Mastronunzio, J.E., L.S. Tisa, and D.R. Benson. 2005. Hydrolytic enzyme genes in the genomes of Frankia CcI3 and EAN1pec. Abstr.R-052, In Abstracts of the 105 th General Meeting of the American Society for Microbiology 2005. ASM, Washington, D.C. ( Atlanta, GA)
Eighmy , T.T., J. Spear, W. Bothner, J. Coulburn, L. Tisa, M. Majko, E. Sullivan, M. Mills, and N. E. Kinner. 2005. Iron Redox Processes on Microfractures in TCE-Contaminated Bedrock. The Joint International Symposia for Surface Microbiology and Environmental Biogeochemistry. Jackson Hole, Wyoming. August 14-19, 2005 .
Normand P., Alloisio N., Marechal J., Lavire C., Pujic P., Berry A.M., Mullin B.C., Tomkins J., Tisa L., Benson D., Choisne N., Demange N., Truong Cong Y.C., Coulloux A., Rouy Z., Cruveiller S., Labarre L., and Médigue C. 2005. The genome of the N2-fixing symbiotic Frankiaalni ACN14A. 2 nd European Conference on Prokaryotic Genomes. Göttingen, Germany September 23-23, 2005.
Niemann, J.M., D. R. Benson, and L. S. Tisa. 2006. Effect of Environmental Stimuli on the Expression of Truncated Hemoglobin in Frankia. July 14-18, 2006, The 14 th International Conference on Frankia and Actinorhizal Plants Umeå, Sweden.
Tisa, L.S. , J. M. Niemann, T. Rawnsley, T. Furnholm, D. R Benson, G. B. Smejkal, P. Lapierre, J.P. Gogarten, Y. Huang, J. Mastronunzio, C. A. Bassi, P. Normand, M. P. Francino, and P. Richardson. 2006 Elucidation of the Frankia EAN1pec Genome Sequence Shows Gene Expansion and Metabolic Versatility. July 14-18, 2006, The 14 th International Conference on Frankia and Actinorhizal Plants Umeå, Sweden.
Benson, B.R., P. LaPierre, J. P. Gogarten, L. S. Tisa, P. Normand and M. P. Francino. 2006.Living small: The reduced genome of Frankia sp. strain CcI3.July 14-18, 2006, The 14 th International Conference on Frankia and Actinorhizal Plants Umeå, Sweden.
Mastronunzio, J., L. S. Tisa, P. Normand and D. R. Benson. 2006. The common secretome of Frankia. July 14-18, 2006, The 14 th International Conference on Frankia and Actinorhizal Plants Umeå, Sweden.
Tisa, L.S. , J. M. Niemann, D. R Benson, G. B. Smejkal, P. Lapierre, J.P. Gogarten, Y. Huang, J. Mastronunzio, T. Rawnsley, C. A. Bassi, M. P. Francino, and P. Richardson. 2006. Post-Genomic Exploration of the Actinorhizal Symbiosis: What can we learn from the Frankia genomes and where do we go from here? August 4-10, 2006, 5 th International Symbiosis Society Congress Vienna, Austria.
Ganapathi, S., S. Minocha, L.S. Tisa, and R. Minocha. 2006. The effects of chronic nitrogen additions on soil microbial diversity at Harvard Forest, MA. August 5-9, 2006. Plant Biology 2006 (American Society for Plant Biologists).
Tisa, L.S. , D. R Benson, G. B. Smejkal, P. Lapierre, J. P. Gogarten, P. Normand, M. P. Francino, and P. Richardson. 2007. Living Large: Elucidation of the Frankia EAN1pec Genome Sequence Shows Gene Expansion and Metabolic Versatility. January 20-27, 2007, 15 th International Congress on Nitrogen Fixation Cape Town, South Africa.
Sen, A., S. Sur, A. K. Bothra, D.R. Benson, and L.S. Tisa. 2007. Codon Usage Patterns and Predicted Highly Expressed Genes for Three Frankia Genomes and the Implication on Life Style. Abstracts of the 107 th General Meeting of the American Society for Microbiology 2007. ASM, Washington, D.C. ( Toronto, Canada).
Mastronunzio , J., L. Tisa, P. Normand, D. Benson. 2007. The Reduced Secretome of Frankia Suggests Symbiosis by Passivity. Abstracts of the 107 th General Meeting of the American Society for Microbiology 2007. ASM, Washington, D.C. ( Toronto, Canada).