Primary research interest

Microbial physiology and biochemistry of metalloenzymes

About me

I hold a Phd (Dr. rer.nat.) from the University of Bonn (Germany) and am a Professor in the School of Chemistry and Molecular Biosciences at UQ. My group investigates how bacteria, including human pathogens, and their metabolic activities shape the environments they inhabit. My research is highly interdisciplinary and connects microbial physiology and protein characterization with various disciplines in biochemistry and chemistry such as spectroscopy and structural biology. I have previously held an ARC Australian Research Fellowship and am a Fellow of the Australian Society of Microbiology.

Research focus and collaborations

Resistance of bacterial pathogens to reactive chlorine and sulfur compounds
Haemophilus influenzae is completely adapted to the human respiratory tract which is its only known niche. This bacterium is able to withstand high concentrations of antimicrobial compounds generated by the innate immune system, such as hypochlorite (bleach) and its derivative, N-Chlorotaurine. The mechanisms of this resistance are currently not well documented and H. influenzae genomes do not encode known regulators of responses to hypochlorite stress.

This project aims to understand the type of cellular damage caused by reactive chlorine species but also naturally occurring antimicrobial sulfur compounds such as allicin, and to identify proteins and enzymes that are required for survival of H. influenzae and other related pathogens in the presence of these antimicrobial reagents. A further target is the pathway of signal transduction and the nature of the molecular signal that activates the Cl- and C- stress protective responses in H. influenzae. First results indicate the involvement of a number of periplasmic enzymes with links to the H. influenzae respiratory chain as key elements in resistance to reactive chlorine species, and we recently identified a novel type of hypochlorite responsive regulator.

You are what you eat - the function of metabolic specialization for colonization of host organisms

Nutrient acquisition and energy generation are essential processes for bacterial pathogens during infection. However, in many cases, including Haemophilus influenzae, the exact types of nutrients that are accessed by the bacteria during infection and more particularly, how access to specific carbon sources can affect infection duration and the ability of bacteria to colonize a host organism is not well understood. We have shown that the H. influenzae nutrient profile is highly adapted to the human respiratory tract (PLOS Pathogens, 2022), and are now investigating how the different classes of preferred nutrients affect virulence. The aim of this work is to understand the H.influenzae metabolic network, and identify enzymes and substrates that are essential for infections in humans.

Metalloenzymes and bacterial pathogenesis

Metalloenzymes are involved in key energy-generating processes in living cells, and they contribute significantly to the adaptation of microorganisms to different environmental conditions. This project investigates how respiratory enzymes aid pathogens in colonising different niches in the host and how these enzymes might be exploited as future drug targets.

Bacterial sulfur compound oxidation

Energy generation from inorganic compounds, including inorganic forms of sulfur, is one of the special properties of certain bacteria. This process contributes significantly to the biogeochemical sulfur cycle, to the bioavailability of sulfur for plant growth in soils and to the detoxification of various volatile sulfur compounds, some of which are known to be climate active. We are investigating the metabolic pathways and enzymes involved in these processes, as well as their regulation in response to changing environmental conditions.

Sulfite oxidizing enzymes - what makes them indispensable for living cells?

Sulfite oxidizing enzymes are found in almost all types of living cells, and especially bacteria are known to harbour a great variety of these enzymes. However, it is unknown what the metabolic role of sulfite oxidation is. We are investigating the diversity of these enzymes, the reactions catalysed by the three structurally distinct known types of these enzymes with a view to uncovering the role of these evolutionarily old enzymes for cellular function.


My group has extensive collaborations with research groups overseas and at UQ and other Australian universities.

Funded projects

  • NHMRC Ideas Grant 2023-2025
    How does metabolic conditioning of the host environment enhance persistence of Haemophilus influenzae infections?
  • NHMRC Project Grant 2019-2021
    Immune recognition of upper airway microbiota in early life as a determinant of respiratory health in children
  • NHMRC Project Grant 2015-2019
    Immune recognition of upper airway microbiota in early life as a determinant of respiratory health in children
  • NHMRC Project Grant 2013-2015
    Metabolism-driven interactions of non-typeable Haemophilus influenzae and its host: a critical factor in infection?

Teaching interests

Microbiology, molecular biology and protein chemistry, general biochemistry:

  • BIOL1020 Genes, Cells & Evolution
  • MICR3003 Molecular Microbiology
  • MICR3004 Microbial Genomics
  • BIOC3005 Molecular Systems Biology (coordinator)
  • SCIE3260/61

Achievements and awards 

  • Fellow of the Australian Society for Microbiology (2011-) 
  • ARC Research Fellowship (2008-2012)
  • Outstanding Editor Award (Frontiers in Microbiology, 2021) 
  • David White Excellence in Teaching Award (Australian Society for Microbiology, 2022)
  • Distinguished Service Award (Australian Society for Microbiology, 2022)
  • Chair of the ASM Queensland branch committee (2018-2022)
  • Grant panel member NHMRC (2016, 2017, 2022, 2023) & Swiss National Science Foundation (2021)
  • Specialty Editor in Chief for Frontiers in Microbiology, Microbial Physiology and Metabolism (2022)

Featured publications

Researcher biography

Associate Professor Kappler (ORCiD: 0000-0002-2642-1319) is Group Leader in the School of Chemistry and Molecular Biosciences at UQ, and Chair of the Metals in Biology group. She held an ARC Australian Fellowship (2008-12) and has proven expertise in managing research projects funded by ARC & NHMRC project grants (>$2.5 million) as well as funding from other agencies. A/Prof. Kappler has > 20 years experience in bacterial physiology and the investigation of enzyme function and metabolic pathways in a wide variety of bacteria, with a particular focus on bacterial sulfur metabolism. Over the past ~10 years she has developed an extensive program of research on the physiology and pathogenesis of the human respiratory pathogen Haemophilus influenzae. Her laboratory is investigating the role of H. influenzae metabolism for host-pathogen interactions, as well as molecular defences against antimicrobials produced by the human immune system (publications: Front. Microbiol., 2015, 2016, 2021, Res. Microbiol. 2018, Adv. Microb. Physiol. 2019, 2xACS Infect. Dis. 2020) Her research has contributed to the development of a novel model of H. influenzae infection that is based on primary human nasal cells differentiated at Air-Liquid Interface.

A/ Prof. Kappler is regularly invited to present her work at international conferences (GRCs, MoTec, EMBO Microbial Sulfur Metabolism, Biometals), and has extensive expertise in the successful supervision of research students and has graduated 10 PhD, 24 Masters and 28 Honors students. She has been the Chair of the UQ Institutional Biosafety Subcommittee (2018-2021), and is the current Chair of the Australian Society for Microbiology (ASM) Queensland branch committee and a member of the ASM national council.