Sam Manna - ASM mini-interview with Dr Sanja Aracic, Postdoctoral Research Fellow at La Trobe University

Posted by on 17 June 2015 | Comments

SM: Can you tell us a little bit about your PhD?

SA: Curdlan, an extracellular polysaccharide (EPS), is produced by Agrobacterium. The most consistently described feature of curdlan production is that it occurs optimally during stationary phase under N-limiting and C-rich conditions. My PhD investigated the genetic basis for the association between curdlan production and N-limitation in Agrobacterium sp. Investigations dissected the role of the widely recognised global two-component regulatory system, NtrB/C, in curdlan production and also the role of the less well characterised NtrY/X system. The study advanced knowledge of the requirements, roles and consequences of these two-component regulatory systems in curdlan production. It also revealed unexpected effects on the production of additional EPS (EPS-X and EPS-Y) and highlighted a regulatory interplay between all three EPS. This study provided insight into additional regulatory controls that apply in curdlan production including the importance of metal ions. Investigations of survival advantages that accrue from EPS production revealed that curdlan and EPS-X serve different functional roles in the life of Agrobacterium, presumably enhancing its ability to occupy a variety of niche habitats.

SM: What is your current area of research?

SA: Detection and quantification of a wide range of hazardous substances (e.g. heavy metals) is required to minimise harm to the ecosystem of contaminated environments. Analytes of these hazardous substances can enter and accumulate in the food chain causing potential harm to humans. Current detection methods of contaminants in water and soil environments are not always practical as they are time-consuming, costly and require off-site testing. These limitations can be overcome using whole cell biosensors. The ability to genetically manipulate regulatory elements to produce a detectable and measurable signal with a range of sensitivities and specificities has resulted in the utilisation of commonly used laboratory microorganisms as biosensors. For whole cell biosensors to be feasible for the detection of contaminants in the environment, a wider range of microorganisms with integrated output systems is required. This study is focused on utilising electroactive bacteria (Pseudomonas, Shewanella and Geobacter) as biosensors. These microorganisms can interact directly with electrode surfaces and have the potential to be integrated into electronic devices.

SM: What made you choose this area of research?

SA: I love investigating how things work and why microorganisms behave the way they do. With this knowledge I can then manipulate the microorganisms to produce a desired phenotype. For example, by altering the nutrients available to Agrobacterium I can either enhance or inhibit the production of an extracellular polysaccharide, similarly I can genetically modify the organism so it overproduces an extracellular polysaccharide. In my current research, I am applying the same set of skills to manipulate microorganisms to produce a measurable signal in response to various contaminants in the environment.

SM: Where do you see yourself in five years?

SA: Ideally I would like to do another Postdoc where I can apply the skills I have obtained during my PhD and current Postdoc position as well as learn new techniques.

SM:What advice would you give to any students or early career researchers with a desire to become successful researchers?

SA: Make the most of all the opportunities that come your way. Small things such as participating in the 3 Minute Thesis Challenge or volunteering in a laboratory once a week or even helping other PhD students can present wonderful opportunities for collaborations and even a Postdoc position.

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