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Associate Professor Michael Kertesz

Research Interest

As a molecular microbial ecologist, the science that fascinates me most revolves around questions of functional interactions, especially in soil and rhizosphere environments. Soil and roots constitute a highly dynamic and complex ecosystem – within this microbial community, understanding who is doing what, when and with whom can yield a host of new insights, many of which have practical implications for sustainable agriculture.

Summary

I am most interested in how bacteria react to changes in their surroundings, especially in soil and around plant roots (the “rhizosphere”). The work of my group focuses in particular on three areas:

Bacterial metabolism of organosulfur and how sulfur availability in soils (usually as sulfonates or sulfate esters) affects soil microbes,

Plant-microbe interactions in relation to plant stress (P limitation, S limitation, UV, herbivore attack),

Microbial community dynamics and gene expression in contaminated soils, especially in relation to bioremediation and rhizoremediation applications.

Microbes are vitally important members of the rhizosphere community, and many of them play important roles in stimulating nutrient uptake and in protecting plants from pathogen attack. Our previous work has characterized a series of novel genes and enzymes that are involved in the mobilization of organically-bound sulphur by bacteria, including several novel sulfonatases and sulfatases. These are especially important in soil environments, where >95% of the sulfur present is organically bound. We are investigating the mechanisms by which plants and microbes work together to adapt to conditions where sulfate or phosphate are limiting for growth, looking at how the specific sulfatase, sulfonatase and phosphatase genes are regulated in the root environment and how nutrient supply affects microbial community dynamics in the rhizosphere using microarray analysis, real-time PCR studies, and molecular ecology tools.

Bioremediation is the application of naturally occurring or introduced microbes to clean up contaminated sites, and development of these new technologies has generated much interest. We are examining the survival of bacteria with bioremediative capability in soils that are heavily contaminated with polycyclic aromatic hydrocarbons (PAHs), using molecular techniques of community analysis to quantify the survival and activity of introduced bacteria together with the native microflora. Many of these bacteria survive best in the rhizosphere, and so our studies have also led us to examine the bacterial communities involved in phytoremediation applications.

Track Record

Michael Kertesz started his academic career as an organic chemist, with a B.Sc. from Monash University, followed by a Ph.D. on chlorophyll and bacteriochlorophyll biosynthesis at the University of Cambridge (United Kingdom). From there he moved to Switzerland to work at the Federal Technical University (ETH Zurich), first as a postdoc in Plant Sciences, investigating glyphosate degradation and then as a group leader in Microbiology, working on bacterial sulfonate metabolism. In 2000 this led him to a senior lectureship at the University of Manchester, where he developed his microbial ecology interests further to look at the effect of nutrient limitation on soil microbial communities and environmental gene expression. In mid-2009 he joined the University of Sydney as Associate Professor in Soil Microbiology. He is on the Editorial Board for the journal Microbiology, and served until recently on the Peer College of the UK Natural Environment Research Council (NERC).

Recent publications

  • Schmalenberger, A., Hodge, S., Hawkesford, M.J., and Kertesz, M.A. (2009) Sulfonate desulfurization in Rhodococcus from wheat rhizosphere communities. FEMS Microbiol. Ecol. 67, 140-150.
  • Schmalenberger, A., Hodge, S., Bryant, A., Hawkesford, M., Singh, B. K. & Kertesz, M. A. (2008). The role of Variovorax and other Comamonadaceae in sulfur transformations by microbial wheat rhizosphere communities exposed to different sulfur fertilization regimes. Environ. Microbiol., 10, 1486-1500.
  • Tralau, T., Vuilleumier, S., Thibault, C., Campbell, B.J., Hart, C.A., & Kertesz, M. A. (2007) Transcriptomic analysis of the sulfate starvation response of Pseudomonas aeruginosa. J. Bacteriol., 189, 6743–6750.
  • Jones, C., Kertesz, M., Gallois, P. & Preziosi, R. (2007). Merging ecology and genetics in a tritrophic species interaction. Amer. Naturalist, 170, 492-499.
  • Kertesz, M.A., Fellows, E., and Schmalenberger, A. (2007) Rhizobacteria and plant sulfur supply. Adv. Appl. Microbiol., 62, 235-268.
  • Schmalenberger, A. & Kertesz, M. A. (2007). Desulfurization of aromatic sulfonates by rhizosphere bacteria - high diversity of the asfA gene. Environ. Microbiol. 9, 535-545.
  • Cunliffe, M., Kawasaki, A., Fellows, E. & Kertesz, M. A. (2006). Effect of inoculum pre-treatment on survival, activity and catabolic gene expression of Sphingobium yanoikuyae B1 in an aged PAH-contaminated soil. FEMS Microbiol. Ecol. 58, 364-372.
  • Cunliffe, M. & Kertesz, M. A. (2006). Autecological properties of sphingomonads involved in the degradation of polycyclic aromatic hydrocarbons in soils. Appl. Microbiol. Biotechnol. 72, 1083-1089.
  • Mirleau, P., Wogelius, R., Smith, A. & Kertesz, M. A. (2005). Importance of organosulfur utilization for the survival of Pseudomonas putida in soil and rhizosphere. Appl. Env. Microbiol. 71, 6571-6577.
  • Kertesz, M. A. & Mirleau, P. (2004). The role of soil microbes in plant sulfur nutrition. J. Exp. Bot., 55, 1939-1945.

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