Microbiology

Zhongguo Xiong, PhD, is an associate professor in the School of Plant Sciences, College of Agriculture and Life Sciences at the University of Arizona, and a faculty member in the Undergraduate Program of Microbiology. Dr. Xiong is a 2012 winner of the Bill Gates and Melinda Foundation Grand Challenges Explorations in Global Health, and has more than 20 years of research experience on RNA viruses of important crops and native plant species. Dr. Xiong research encompasses a wide range of subjects that include virus diversity, recombination, RNAi suppression, host resistance and resistance-breaking, replication and movement of RNA viruses, and how all these are related to the control and management of viral diseases. He was one of the first researchers to discover ribosomal frameshifting as a gene expression mechanism in plant RNA viruses and to demonstrate recombination between transgene mRNA and genomic RNA of an infecting virus. His recent research on Citrus tristeza virus has revealed its genome stability, unusual for an RNA virus, and the promiscuous recombination between viral strains as the major factor driving Citrus tristeza virus evolution. His recent collaboration with Dr. Martha Hawes has led to the discovery that extracellular DNA, secreted DNases, and proteins are important immunity and pathogenicity factors in the plant-microbe interactions in the rhizosphere. Dr. Xiong has strong ongoing international collaborations on emerging viral diseases of tomato, pepper, papaya, and banana. His recent research interests include genome editing to engineer immunity against viral infection and using the next generation sequencing to explore viral population genomics and genetic diversity and to discover new viruses and novel viral strains.

Michael Worobey, PhD, uses the genomes of viruses to trace the evolution of major communicable diseases, such as HIV/AIDS and influenza. He employs an evolutionary approach to understand the origins, emergence and control of pathogens, in particular RNA viruses and retroviruses such as HIV and influenza virus. The research program integrates fieldwork, theory and methodology, molecular biology, and molecular evolutionary analysis of gene sequences in a phylogenetic framework.Current wet-lab projects in Dr. Worobey’s Biosafety Level 3 facility involve recovery of damaged and/or ancient DNA from a variety of sources including paraffin-embedded human tissue specimens, blood smears, and museum specimens. The two main efforts are: 1) reconstructing the emergence of HIV-1 group M in central Africa and North America using fossil HIV-1 sequences, and 2) investigating the evolution of AIDS-related viruses in wild-living African primates using non-invasively-collected samples.

Microbe-host interactions Specifically microbial pathogenesis Concomitant immune response with respect to host age

Dr. Viswanathan’s research efforts over the past 12 years have focused on the mechanisms of pathogenesis of the diarrheal disease pathogens enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC). His laboratory characterized EPEC and EHEC virulence factors (specifically those secreted into host cells) and evaluates their effect on host cell physiology including barrier function, cell death pathways, and effects on innate immune responses. His specialization is innate immune signaling by intestinal epithelial cells in vitro and in vivo, and includes the use of cutting-edge technologies such as in vivo phosphoproteomics, and single-cell manipulation during bacterial infection. He also offers a very popular upper-division course in pathogenic bacteriology, and actively mentors undergraduate and graduate students, and post-doctoral fellows at the UA. Keywords: Pathogenic E. coli, Clostridium difficile, infection, host-pathogen interactions

I am an integrative microbial ecologist with training in microbial ecology, evolutionary biology, mycology, and genomics. I am an Assistant Professor of Ecosystem Genomics in the Department of Agricultural and Biosystems Engineering and the BIO5 Institute. I completed a BA in Biological Sciences from the University of Missouri-Columbia and my PhD in Plant Pathology from University of Arizona’s School of Plant Sciences. Keywords: plant-microbe interactions, comparative genomics, microbial ecology, fungal endophytes

Magdalene So, PhD, is a Professor in the Immunobiology Department and Director of the Microbial Pathogenesis Program at the University of Arizona College of Medicine. Dr. So is recognized internationally for her research in the microbial pathogenesis. Her research focuses on two medically important bacterial pathogens: Neisseria gonorrhoeae, which causes over 100 million new cases of sexually transmitted infections each year worldwide, and Neisseria meiningitidis, which frequently causes meningitis epidemics in Subharan Africa. Her goal is to understand on how these two pathogens cause disease, with the aim of applying this information to developing new antibiotics for treating these infectious agents and improving current methods of vaccine development. Dr. So recently expanded her research to the commensal species in the Neisseria genus. These bacteria are normal inhabitants of the body and are closely related to the two pathogenic species; but unlike their pathogenic cousins they do not cause disease. Dr. So’s new research effort seeks to determine the differences in behavior of commensal and pathogen Neisseria. Dr. So’s research approach is multidisciplinary, involving concepts and techniques in biophysics, bioinformatics, cell biology, biochemistry and genetics. Collaborators from institutions around the world contribute to this effort. Dr. So has published over 100 peer-reviewed research papers in internationally renowned journals, and over 20 reviews and book chapters. She holds several patents as a result of her research. She is frequently invited to speak at universities and national and international meetings. She is a member of the American Academy of Microbiology, an elected body, and serves on the scientific boards of several research centers. Over the course of her career, Dr. So has trained over 44 postdoctoral fellows and graduate students. The majority of her trainees are internationally recognized researchers in their own right. Keywords: Infectious disease, microbiology

Sadhana Ravishankar, PhD, focuses on the stress response in foodborne pathogenic bacteria, including methods of pathogen control and natural antimicrobials. In the lab, Dr. Ravishankar attempts to control foodborne pathogenic bacteria including antibiotic resistant strains using various technologies and multiple hurdle approaches. Natural antimicrobials and their applications in various foods, antimicrobial and anti-oxidative activities of plant compounds also interest her. Bacterial attachment, biofilm formation and their control along with stress tolerance responses of foodborne pathogenic bacteria, and mechanisms of stress response in bacteria are some other subjects of research for Dr. Ravishankar’s lab.

All viruses hijack host cell machinery to facilitate their replication. Producing infectious viral progeny relies on host cell metabolic pathways to provide energy and building blocks such as nucleotides, amino acids, and lipids. I am interested in investigating the molecular remodeling of cellular metabolic and lipid environments by viruses. The overall goal of my research in dissecting the complex virus-host metabolism interactions is to guide the development of novel antiviral therapies. Keywords: Infectious Disease, Virology, Metabolism, Lipidomics

Dr. Pepper is an environmental microbiologist whose research has focused on the fate and transport of pathogens in air, water, soils and municipal wastes. More recently he has investigated the potential for real-time detection of contaminants in water distribution systems. He also teaches a graduate level laboratory class on Environmental Microbiology, and an undergraduate class on Pollution Science. His latest adventure is the development of the Water and Energy Sustainable Technology Center (WEST), a new 22000 square foot laboratory complex which focuses on the water:energy nexus.

Metals serve as vital nutrients to all biological systems. During infections, bacteria must not only acquire all metals necessary for survival from within the host, such as calcium or manganese, but must also efflux metals that are toxic or in excess such as copper. The overall goal of my laboratory is to investigate how bacteria maintain homeostasis within the metal milieu. This goal involves determining how metals are processed, the orchestrated response during metal sensing, and the role that the host plays in this process during infection. Understanding how bacteria interact with metals during infections will identify novel therapeutic strategies against bacterial infections. Keywords: Infectious Diseases, Antibiotic resistance, Bacterial Pneumonia