Associate Professor Xue-Xian Zhang PhD

Contact details

• Ph: (09) 4140800 ext. 41191
  Location: 02, 14
  Campus: Albany

Qualifications

• Doctor of Philosophy - Huazhong Agricultural University (1993)

Research Interests

My research focuses on bacterial adaptation to their natural environments, such as soil and eukaryotic hosts. Specifically, modern tools in molecular biology are used to elucidate the genetic and physiological responses of bacteria to the environment, aiming to provide insights into the nature of the complex environment itself. The work is largely performed in a model organism of Pseudomonas fluorescens SBW25 (a plant growth-promoting bacterium) and was recently extended to pathogenic bacteria of plants and humans, and the microbial communities in the soil.

The microbiological research performed in my lab range from molecular biology to ecology and evolution. The molecular biology work has been focused on the genetic characterization of genes involved in nutrients acquisition, and the research was supported by a Marsden Fund grant of the Royal Society of New Zealand (2006-2010). My experimental evolution work uses the fast-growing bacterium as a model system, whereby some important questions in biological evolution have been addressed. These include the evolutionary mechanisms of cooperation (and cheating), bet hedging, the roles of immigration in biological diversification, and the effects of genetic constraints on evolutionary trajectories. Moreover, I have been actively involved in ecological research on the dynamic changes of soil microbial community in response to climate changes.

With the widespread increase of bacterial resistance to antibiotics, new strategies to prevent and treat healthcare-associated infections are urgently required. Two projects in my lab are targeting infectious diseases of humans. One project focuses on Pseudomonas aeruginosa, an environmental pathogen that causes a wide range of healthcare-associated infections and pulmonary infections in people with chronic lung diseases, particularly cystic fibrosis (CF). We are testing a new hypothesis that urocanate, a histidine metabolite, accumulates in human tissues and acts as a signalling molecule that initiates bacterial infection. Results from this project will define the mechanism used by P. aeruginosa to identify susceptible host tissues and express pathogenicity traits at the correct time and place. This knowledge will form a basis for the development of new strategies to prevent bacterial infectious diseases. Specifically, analogues of urocanate or inhibitors of the bacterial receptor have the potential to interrupt the normal process of host recognition, and thus prevent bacterial infection.

The other project aims to reduce the rate of hospital-associated infections (HAI), which currently affect ~10% of hospitalised patients in New Zealand public hospitals. We are exploring a novel strategy in preventing HAI, which involves the use of self-sanitising copper-containing surfaces on items commonly touched in hospitals, and provide sustained protection against microbial contamination. More specifically, we perform experiments that can help increase our understanding of rapid bacterial killing on metallic copper and the potential of pathogens to develop resistance.

Research Opportunities

• Targeting the mechanism of host recognition to prevent bacterial infections  (28/02/2014) Elucidate the regulatory roles of HutC in the expression of bacterial virulence factors and the association between urocanate concentrations in human tissues and predisposition to bacterial infection.

Thematics

21st Century Citizenship, Resource Development and Management, Health and Well-being

Area of Expertise

Field of research codes
Biogeography and Phylogeography (060302): Biological Sciences (060000): Community Ecology (060202): Ecology (060200): Evolutionary Biology (060300): Evolutionary Impacts of Climate Change (060306): Gene Expression (incl. Microarray and other genome-wide approaches) (060405): Genetics (060400): Host-Parasite Interactions (060307): Infectious Agents (060502): Microbial Genetics (060503): Microbiology (060500)

Keywords

Microbiology, Experimental Evolution, Microbial Ecology, Bacterial Genetics

Languages

• English
  Last used: now
  Spoken ability: Excellent
  Written ability: Excellent
• Chinese
  Last used: 2000
  Spoken ability: Excellent
  Written ability: Excellent

Teaching Statement

I am coordiating two papers 122.231 (Genes and Gene Expression) and 203.342 (Molecular and cellular Biology), and also invovled in the teaching of 162.214 (Biology of Microorganisms) and 246.302 (Research Themes in Natural Sciences)

Courses Coordinated

• 122.231 Genes and Gene Expression
• 203.342 Molecular and Cellular Biology

Current Doctoral Supervision

Supervisor of:

• Kiran Sreeja Jayan - Doctor of Philosophy
  Characterization of genes for the utilization of histidine and its metabolites in a human pathogenic bacterium Pseudomonas aeruginosa PAO1

Co-supervisor of:

• Indika Serasinghe Mudiyanselage - Doctor of Philosophy
  Investigation into the development of probiotic starter culture for industrial production of sauerkraut
• Huei-Yi Lai - Doctor of Philosophy
  Mechanisms of maintaining antibiotic resistance without antibiotic selection
• Farhad Sadeghpour Golzar - Doctor of Philosophy
  Experimental Evolution Under Predation in Pseudomonas Fluorescens SBW25

Completed Doctoral Supervision

Supervisor of:

• 2019 - ~ Naren - Doctor of Philosophy
  Regulation of histidine catabolism in Pseudomonas fluorescens SBW25

Co-supervisor of:

• 2020 - Amber Paulson - Doctor of Philosophy
  Temperature- and host-dependent transcriptional responses in the entomopathogenic bacterium, Yersinia entomophaga MH96
• 2015 - Yunhao Liu - Doctor of Philosophy
  Molecular mechanism of xylose utilization in a plant growth-promoting bacterium Pseudomonas fluorescens SBW25