Technology

Event Date: 
Wednesday, August 29, 2012 - 19:00 - 20:00
Institution: 
University of Sydney
Title: 

The distribution of Phytophthora in the Greater Blue Mountains WHA.

Abstract: 

 
Disease caused by Phytophthora cinnamomi is becoming increasingly prevalent within the Greater Blue Mountains World Heritage Area (GBMWHA), yet little is known of the distribution of pathogens or the impact of disease. An understanding of the disease distribution is required to develop management strategies in natural ecosystems like the GBMWHA. However where only sporadic information is available, conservation efforts may be limited by incomplete sampling for pathogen presences due to remoteness and inaccessibility of many sites. Risk models can overcome some of these drawbacks. Hence, we modelled the distribution of P. cinnamomi in the GBMWHA by combining landscape and environmental information using a GIS approach. Data layers were reclassified into risk layers using FUZZY logic such that localities conducive to dieback were given the highest risk rating enabling the compilations of a relative risk surface. The area identified with the highest risk was the Blue Mountains National Park primarily due to optimal temperatures for pathogen development, known infestations and an abundance of roads, tracks and paths To investigate the range of Phytophthora infestation soil sampling was conducted based on the risk levels in the model using a stratified random approach. Results indicate the pathogen is widespread across the WHA. However, infestation is sporadic with negative samples occurring frequently. Isolations were more common in areas of greater human activity, such as the highly visited Blue Mountains National Park. Results also implicate vehicles in anthropogenic dispersal. Further testing is being undertaken to improve our understanding of the pathogen-environment-disturbance relationship and genetic analysis of isolates will explore inter and intraspecific species variation. Information gained from the survey will allow managers to prioritise hygiene and quarantine measures, and facilitate the development of ecological models of the distribution of Phytophthora within the GBMWHA. 

Event Date: 
Tuesday, July 24, 2012 - 18:15 - 18:30
Institution: 
University of NSW
Title: 

Development of an Australian 1,2-Dichloroethane degrading culture

Abstract: 

 
1,2-Dichloroethane (DCA) is one of the most common organochlorine groundwater contaminants worldwide. The successes of bioremediation field studies with organochlorine respiring bacteria have proved the efficacy of the method to degrade such contaminants in situ. The objective of this study was to demonstrate that a DCA degrading consortium, named AusDCA could be used to bioaugment a DCA contaminated acidic aquifer in situ. Functional characterisation experiments of AusDCA in batch cultures showed that the culture could dechlorinate high concentrations of DCA (6.3 mM) to ethene anaerobically at pH 5.5 and pH 6.5 and was not inhibited by approximately 15 µM of chloroform (CF). 

 
Kerensa McElroy (UNSW) started us off immersing the audience in deep sequencing in order to understand pathogen evolution in biofilms. Two model pathogens, Phaeobacter gallaeciensis and Pseudomonas aeruginosa, were used to grow biofilms under conditions that select for reproducible phenotypic diversification. Variations in the genetic structure were revealed addressing different stages of biofilm development. Kerensa could describe genetic variation accurately and comprehensively within evolving populations using her established approach in genome-wide deep sequencing.
 

JAMS Meeting Report – April 2012
by Thomas Jeffries
 
There was a good turnout on ANZAC day eve for three interesting talks, pizza and free local beer.
 
Kicking off the evening was John Lee, from the University of Georgia, with his ambitiously titled talk “Bioluminescence: The First 3000 Years”.  After a historical introduction to the long running observation of bioluminescence, via the discovery in 1672 that oxygen was necessary for bacterial luminescence, John told us how it was determined that bioluminescence is an enzyme mediated chemical reaction involving “luciferase” and "luciferine". In the modern age of biochemistry it was determined that ATP is the substrate in this reaction.  Following the elucidation of the structure of firefly luciferase in 1959, modern techniques (i.e. picosecond dynamic fluorescence spectroscopy and NMR) have allowed researchers to uncover the enzymes and processes involved in bioluminescence.  One of the most important of these enzymes Green-fluorescent protein (GFP) was discovered in jellyfish by Shimomura (who evidently has a lab at his house!) and led to his Nobel prize in 2008.  Due to GFP’s widespread use in research, it is regarded as one of the most important proteins in science.
 

Event Date: 
Wednesday, May 30, 2012 - 18:00 - 18:15
Institution: 
UNSW
Title: 

Deep sequencing of evolving populations in bacterial biofilms

Abstract: 

 

Bacterial communities growing as biofilms are subject to a distinct lifecyle, featuring initial surface attachment, microcolony formation and dispersal of cells. Bacterial biofilms are sometimes characterised by high levels of heritable phenotypic variants, presumably resulting from genetic diversification during the biofilm lifecyle. As biofilms are a favoured lifestyle of many environmental and pathogenic bacteria, identifying the evolutionary processes responsible for this diversification has important implications, both for our understanding of ecological processes, such as niche adaptation, and to clinically relevant questions, such as the evolution of antibiotic resistance.
I've used longitudinal genome-wide deep sequencing to reveal the underlying genetic structure of bacterial populations growing as biofilms, for the model organisms Phaeobacter gallaeciensis 2.10 (an abundant marine bacterium) and Pseudomonas aeruginosa 18A (a clinical Cystic Fibrosis isolate). Biofilms were grown under defined laboratory conditions known to generate reproducible phenotypic diversification. Samples from different stages of biofilm development were then sequenced to very high coverage (>800x). By accounting for sequencing errors using a matched-sample approach, variants with population frequencies as low as 0.5% could be accurately identified.
In general, the extent and nature of genetic variation was comparable for biofilms of both model organisms, being driven by selection for a small number of non-synonymous variants within key genes involved in biofilm- and competition-related pathways. These results also demonstrate that genome-wide deep sequencing can rapidly, accurately and comprehensively describe genetic variation within evolving populations.

 

Event Date: 
Tuesday, April 24, 2012 - 19:15 - 20:00
Institution: 
Nanyang Technological University, Singapore / UNSW
Title: 

The Great Escape: Biofilm formation and dispersal

Abstract: 

Bacteria form biofilms on almost all surfaces, ranging from ship hulls to cooling towers, to indwelling biomedical devices.  Biofilms also play positive roles, for example, floc and granule formation for the biological remediation of contaminated water.  Therefore, there is strong drive to understand the processes of biofilm formation, to either eliminate biofilm formation in some industrial processes and human health, or to encourage their formation, for processes such as remediation.  To develop innovative, environmentally friendly, biofilm control technologies, it is essential to understand the process of biofilm formation and how bacteria control the process of dispersal. 
Bacteria rapidly respond to changes in nutrient conditions, and we have shown that depletion of nutrients, e.g. carbon limitation or nitrogen, can lead to dispersal of bacterial biofilms.  This process is mediated via an intracellular second messenger cascade, using cAMP and c-di-GMP and may also be linked to other physiological signals such as nitric oxide mediated dispersal. 
We have also shown that biofilm development and dispersal is dependent on a prophage carried by Pseudomonas aeruginosa.  The phage plays an important role in multiple aspects of biofilm development and stability and we are beginning to unravel the mechanisms result in phage conversion which ultimately are linked to biofilm development.

Sydney may have failed to deliver some sunshine on the last day of a slightly extended summer, but this didn’t dampen the spirits of Sydney’s microbiology community who turned out in numbers for the Inaugural JAMS Anniversary half-day meeting at the Australian Museum. This special meeting celebrated the first birthday of JAMS, an ASM special interest group that aims to bring together research microbiologists, post-docs and PhD students working in non-clinical research from all institutes.

Special thanks must go to the sponsors of the meeting: POCD scientific; Becton, Dickinson and Company; Macquarie University; The University of Sydney; The University of NSW; The University of Technology, Sydney, and; The University of Western Sydney. Another special thank you must also go to Federico Lauro (UNSW) and other members of the JAMS steering committee for organising the anniversary meeting and for their continued commitment to JAMS. The steering committee would also like to thank the Australian Museum who kindly provided the venue for our regular meetings and who hosted this special event.

Event Date: 
Wednesday, March 28, 2012 - 18:00 - 18:15
Institution: 
University of Sydney
Title: 

Genetically controlled network architecture in the filamentous fungus Neurospora crassa constrains amino acid translocation

Abstract: 

Effective nutrient translocation in fungi is essential for nutrient cycling, mycorrhizal symbioses, virulence and substrate utilization. An interconnected mycelial network is proposed to influence resource translocation, but has not been empirically tested. By comparing amino acid translocation in Neurospora crassa colonies defective in network formation and translocation between wild type colonies of different developmental ages, we can gain insight into the influence of network formation on nutrient translocation.

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