Biology

Event Date: 
Wednesday, April 27, 2011 - 18:00 - 18:15
Institution: 
Maquarie University
Title: 

Transcriptome led microbial discovery.

Abstract: 

Using a genome wide transcriptomic approach, Karl was able to unravel the role of the Pseudomonas global
activator system (GacA/GacS) in the regulation of an extremely broad range of functions including iron acquisition, oxidative stress response, secondary metabolism and motility. Similar work in Acinetobacter baumannii, a bacterium that is emerging as a major human pathogen due to multiple drug resistance, has revealed the antibiotic efflux to be major mode of resistance and led to the discovery of novel resistance proteins. Karl is a post-
doctoral fellow at Macquarie University working in Prof. Ian Paulsen’s group.

Event Date: 
Wednesday, February 23, 2011 - 18:00 - 18:15
Institution: 
UTS
Title: 

Class 1 integrons in genomic islands of pathogenic Pseudomonas aeruginosa isolates.

Event Date: 
Tuesday, January 25, 2011 - 19:15 - 20:00
Institution: 
University of California-Davis
Title: 

Gene flow and speciation in populations of bacteria and archaea from a genomic perspective.

Event Date: 
Wednesday, November 24, 2010 - 18:15 - 18:30
Institution: 
USyd
Title: 

Active partitioning by S. aureus conjugative multiresistance plasmids.

Event Date: 
Wednesday, June 29, 2011 - 19:15 - 20:00
Institution: 
USyd
Title: 

Unravelling the complexities of mosquito-borne disease.

Abstract: 

While the nuisance-biting and public health risks associated with mosquitoes are well known, the biological and environmental complexities that influence those risks are rarely appreciated. Australia has a diverse mosquito fauna and the risks to public health caused by the transmission of disease-causing pathogens such as Ross River virus or Barmah Forest virus can be influenced by an equally diverse range of factors. This presentation will explore how mosquito biology and ecology, local wildlife, environmental and climatic factors, wetland rehabilitation strategies, urban planning and human behaviour can all influence the risks of mosquito-borne disease.

Event Date: 
Wednesday, June 29, 2011 - 18:15 - 18:30
Institution: 
Scripps Inst. of Oceanography, UC San Diego
Title: 

Regulation and heterologous expression of bioactive natural products from the filamentous marine cyanobacterium Lyngbya majuscula.

Abstract: 

The marine cyanobacterium Lyngbya majuscula is well recognized as a rich source of bioactive secondary metabolites that are valued as both drug candidates and resources in biotechnological applications. Although considerable advances have been made in understanding the gene clusters involved in molecule assemblies, the potential of many Lyngbya metabolites has yet to be harnessed because of low yields from field collections and slow growth in laboratory cultures. Two possible routes to improving Lyngbya natural product yields could be through discovery and manipulation of regulatory mechanisms associated with Lyngbya biosynthetic pathways, and establishment of a reliable heterologous expression platform for Lyngbya metabolites. In previous efforts studying the regulation of natural products from Lyngbya, we isolated light related transcription factor proteins that may be used to regulate production of the jamaicamides, neurotoxic compounds from a Jamaican Lyngbya strain. We have developed an approach to monitor rates of jamaicamide A and B biosynthesis in vivo using a combination of mass spectrometry and stable isotope feeding, and found different rates of biosynthesis between these two molecules in light and dark conditions. This approach has been used to measure the effects of a variety of culture conditions on natural product turnover in cyanobacteria. Current efforts towards heterologous pathway expression are focused on the dermatotoxic lyngbyatoxins from a Hawaiian Lyngbya collection. Functional Lyngbya recombinant protein expression has been achieved using the model actinomycete Streptomyces coelicolor, and we are now attempting to determine if Streptomyces is capable of expressing the entire lyngbyatoxin pathway.

Event Date: 
Wednesday, June 29, 2011 - 18:00 - 18:15
Institution: 
UNSW
Title: 

Metabolic methanisation of chloroform by a three component microbial community.

Abstract: 

Chloroform is a highly toxic organochlorine found in subsurface environments due to its poor handling and disposal techniques by industry. Bioremediation of organochlorine polluted environments is a well established technique that utilises dehalogenating bacteria to reductively dechlorinate organochlorines to their hydrocarbon counterpart. One drawback of bioremediation is that chloroform is inhibitory to this microbial process. A key to the advancement of the bioremediation industry is the discovery of dahalogenating bacteria capable of complete chloroform metabolism.

Here we report for the first time a microbial population capable of rapid metabolic transformation of chloroform at high concentrations (~50 ppm) to methane. Cultures were established with sediment sampled 4.5 m below ground surface from an aquifer polluted for over 40 years with a mixture of organochlorine compounds. A combination of functional data, pyrosequencing, quantitative PCR and the application of labelled substrates were used to elucidate the participating microbial community members. Members of the Dehalobacter genus were found to first dehalo-respire chloroform to dichloromethane which was then fermented to formate and acetate. A hydrogenotrophic syntroph (i.e. a methanogen) was then required to drive this process forward to methane.

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