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YILDIZ LAB

Fitnat Yildiz
453 Physical Sciences Building
Phone: (831)459-1444, Email

Lab Members
Selected Publications

Research Focus
Our research focuses on understanding processes that control growth, persistence and transmission dynamics of human pathogens in non-host environments.

Environmental Survival of Human Pathogens: Role of Phase Variation and Biofilm formation.
Alterations to aquatic environments, via natural or anthropogenic factors can directly or indirectly lead to infectious disease outbreaks. At present, little information is available on the molecular ecology and evolutionary dynamics of infectious agents in the environment. Understanding the environmental factors involved in persistence, growth, and transmission of pathogens and the response of organisms to environmental changes will provide information about the emergence or re-emergence of infectious diseases.

Vibrio cholerae, the causative agent of the Asiatic cholera, is an excellent model system to study these processes, because V. cholerae causes periodic, seasonal outbreaks in regions where it is an established member of the indigenous aquatic flora. It is estimated that the disease causes the death of 120,000 people worldwide every year. The pathogens capacity to cause seasonal epidemics is linked to its survival in free-living and in biofilm growth modes in aquatic environments between outbreaks. However, the processes governing the survival of V. cholerae and its adaptability to changes in habitat remain elusive.

V. cholerae has two phase variants which are named as smooth and rugose reflecting the appearance of their colonial morphologies. Reversible phase variation between the rugose and the smooth colonial variants and associated phenotypes are postulated to be an important factor for the survival of the organism. Little is known about the molecular basis of the phase variation and molecular differences between these two colonial variants. Using molecular genetic and genomic approaches we are working towards identification and characterization of the genes and the processes that are associated with the phase variation.

In aquatic habitats V. cholerae is found as attached to various biotic and abiotic surfaces. It has been proposed that attachment of bacteria to surfaces, and subsequent biofilm growth mode, exemplifies a survival strategy. Identification of the genes required for the development of V. cholerae biofilms and of metabolic pathways operating in these biofilms is central to understanding of the sessile lifecycle of the organism. We know very little about the processes that allow V. cholerae to sense, respond, and adapt to a life on a surface. We are studying the signals and regulatory networks that are essential for biofilm formation by V. cholerae by employing the combined use of molecular genetics, functional genomics, proteomics, microbial ecology and microscopy.

Results obtained through these projects will expand our understanding of the environmental life cycle of an important human pathogen and will provide information useful for the prediction and control of cholera epidemics.

LAB MEMBERS

Sinem Beyhan Graduate Student, Environmental Toxicology B.S., Molecular Genetics, Middle East Technical University, Ankara Turkey University My research interest is the survival mechanism of Vibrio cholerae under environmental stress. I am also interested in environmental signals for biofilm formation of Vibrio cholerae.

Kivanc Bilecen Graduate Student, Environmental Toxicology M.Sc., Bioengineering, Sabanci University, Istanbul, Turkey. B.Sc., Biological Sciences, Middle East Technical University, Ankara, Turkey.

Nicholas Fong Postgraduate Researcher Education: BS(Honours) Biotechnology, School of BABS, University of New South Wales Ph.D. Biotechnology, School of Biotechnology and Biomolecular Sciences, University of New South Wales Understanding the molecular basis of the survival mechanisms used by V. cholerae O1 El Tor between epidemics

Nick Shikuma Graduate Student, Environmental Toxicology B.S., Biology, University of the Pacific M.S., Zoology, University of Hawaii, Manoa My research interests include the molecular basis of environmental persistence of Vibrio cholerae between outbreaks.

PAST MEMBERS

• Mira Patel
• Selena Ghiotto
• Aron Weckesler
• J.R. Flanders
• Catharina Caspar Lindley
• Vanessa Soliven, B.S., Biological Science; B.A. Italian Studies
• Bentley Lim, B.S. Biochemistry & Molecular Biology (Phi Beta Kappa) UC Santa Cruz

SELECTED PUBLICATIONS