Gyaneshwar Prasad (GP) Assistant Professor B. S. Osmania University Hyderabad, India M. S. M. S. University Baroda, India Ph.D M. S. University Baroda, India Postdoctoral Fellow University of California Berkeley University of Minnesota, St Paul	Office: Lapham 131C Phone: 414-229-4363 FAX: 414-229-3926 Email: prasadg@uwm.edu Electronic Reserve Materials:
Microbiology

Research Interests

(I) Physiological and regulatory genomics of nutrient limitations in Escherichia coli K12 Bacterial growth and ecology in natural environments is often affected by the availability of nutrients. Recent development of DNA microarray technology has provided significant insights into whole-genome transcriptional changes that occur upon nutrient limitation in the model bacterium Escherichia coli. These studies have shown that the bacteria increase the expression of genes required for the scavenging and utilization of various compounds even when they are not supplemented in the growth medium (Fig 1). My laboratory is interested in elucidating the role of these genes, in particular the role of periplasmic components of the so-called scavenging systems, in internal homeostasis. In addition, bacterial nutrient starvation responses have been studied in the laboratory by employing limitation of a single nutrient (law of the minimum). However, bacteria might encounter limitation of multiple nutrients simultaneously. I am interested in establishing dual/multiple nutrient limiting conditions and studying the gene regulation and bacterial physiology under these conditions. Fig 1. Induction of genes (red spots) for scavenging of various N-containing compounds by N-limitation in E. coli K12> (II) Quest for Biological Nitrogen Fixation in non-legumes Rice (Oryza sativa) and Corn (Zea mays) and are major cereal crops feeding human population. In addition, corn is increasingly being used for production of biofuels. Their production however requires extensive application of Nitrogen (N) fertilizers that is projected to further increase 20-40% to sustain the increasing demand. Production of N fertilizers uses fossil fuels and N fertilizers are the highest on-farm costs. Moreover, the use of fertilizer causes enormous environmental degradation. Therefore, there is an urgent need for supplementing N fertilizers with more environmentally-friendly and sustainable biological nitrogen fixation (BNF). Legume plants make significant contribution of BNF in agriculture through their symbiotic relationship with N-fixing bacteria such as Rhizobium. Recently strains of Burkholderia have also been shown to possess ability to nodulate species of Mimosa. In addition, Burkholderia strains have been isolated from surface-sterilized tissues of rice and corn indicating that Burkholderia has the potential for interactions with both legumes and non-legumes. In a systematic effort to develop a model system to understand interaction of bacteria capable of nodulating legumes with cereals, we propose to study colonization, infection of rice and corn by strains of Burkholderia as well as by novel nodulating strain of Agrobacterium tumefaciens IRBG500 (Fig 2) Fig 2. Nodulation of Sesbania cannabina (A) and colonization of rice (B) by A. tumefaciens IRBG74 marked with GUS.

Selected Publications

Loh KD, Gyaneshwar P, Papadimitriou EM, Fong R, Kim KS, Zhou Z, Inwood W & Kustu S (2006). A new pathway for pyrimidine catabolism. Proc. Natl. Acad. Sci. USA 103: 5114-5119. Gyaneshwar P, Paliy O, McAuliffe J, Jones A, Jordan MI & Kustu S (2005). Lessons from E.coli genes similarly regulated in response to sulfur or nitrogen limitation. Proc. Natl. Acad. Sci. USA 102: 3453-3458. Gyaneshwar P, Paliy O, McAuliffe J, Popham DL, Jordan MI & Kustu S (2005). Sulfur and nitrogen limitation in Escherichia coli K12: specific homeostatic responses. J. Bacteriol. 187: 1074-1090. Goh EB, Bledsoe PJ, Chen LL, Gyaneshwar P, Stewart V & Igo MM (2005). Hierarchical Control of Anaerobic Gene Expression in Escherichia coli K-12: the Nitrate-Responsive NarX-NarL Regulatory System Represses Synthesis of the Fumarate-Responsive DcuS-DcuR Regulatory System. J. Bacteriol. 187: 4890-4899. . Zimmer D, Paliy O, Thomas B, Gyaneshwar P & Kustu S (2004). Genome image programs: visualization and interpretation of Escherichia coli microarray experiments. Genetics 167: 2111-2119. Loyd L, Jones S, Jovanovic G, Gyaneshwar P, Rolfe M, Thompson A & Buck M (2004). Identification of a new member of the phage shock protein response in Escherichia coli, the phage shock protein G (PspG). J. Biol. Chem. 279: 55707-55714. Gyaneshwar P, Naresh Kumar G, Parekh LJ & Poole PS (2002). Role of soil microorganisms in improving P nutrition of plants. Plant Soil 245: 83-93. Gyaneshwar P, James EK, Reddy PM, & Ladha JK (2002). Herbaspirillum colonization increases growth and nitrogen accumulation in aluminium-tolerant rice varieties. New phytol.154: 131-146. James EK, Gyaneshwar P, Mathan N, Barraquio WL, Olivares FL & Ladha JK (2002). Infection and colonization of rice seedlings by the plant growth promoting bacterium Herbaspirillum seropedicae Z67. Mol. Plant Microbe Interact. 15: 894-906