Science

Event Date: 
Wednesday, August 26, 2015 - 19:00 - 19:45
Institution: 
CSIRO
Title: 

The evolution of mutualistic trait variation in rhizobial symbionts across genetic and geographic scales

Abstract: 

Interactions between plants and nitrogen-fixing rhizobial bacteria are characterized by high genetic diversity for traits important to the outcome of the interaction at the population and species level. However, the selective processes underpinning the generation and maintenance of genetic and phenotypic variation in such interactions are not well understood. I will present an overview of data gathered from a series of experiments using interactions between Acacia spp. and their associated rhizobia, and that address questions regarding the ecological and evolutionary drivers of trait variation across different scales.  Specifically, I will discuss how 1) phylogenetic constraint; 2) within-species local adaptation; 3) nutrient availability; and 4) partner diversity and identity, influence patterns of specialization and community structure in legume-rhizobial mutualistic interactions. Our results suggest that both host-bacterial and bacterial-bacterial interactions are important for understanding evolutionary and ecological dynamics and highlight the importance of designing experiments that span different genetic and geographic scales.

Event Date: 
Wednesday, August 26, 2015 - 18:15 - 18:30
Institution: 
CSIRO
Title: 

Effects of temporal pH shifts on ammonia oxidiser community structure and function

Abstract: 

Soil nitrification, the oxidation of ammonia to nitrate, is and driven by bacterial and archaeal autotrophic ammonia oxidisers (AOB and AOA) that carry out the first, rate limiting, step of oxidising ammonia to nitrite.  Previous work has suggested that adaptation and selection in AOA and AOB communities is, to some extent, pH driven.  Acidophilic, acido-neutral, and alkalinophilic groups have been identified by environmental surveys of amoA genes.  These studies of the role of pH in determining ammonia oxidiser community structure and activity have largely relied on spatial pH gradients.  In many managed soil systems (e.g., agricultural systems) edaphic factors (e.g., pH, N concentrations) vary widely temporally and the implications of short term temporal shifts in factors thought to govern oxidiser community structure, and therefore our ability to manipulate edaphic factors to direct community structure, are not well understood.   We investigated the roles of pH in driving nitrifier activity (potential) and community structure over a crop growing season (6 sampling points) in agricultural soils by comparing unamended soils with soils amended with lime to create a temporal pH gradient.  Liming induced a rapid and sustained change in the pH of surface soils (0-10cm), with pH in these soils increasing from 4.8 to 6.5, while in subsurface soils pH increased to a lesser degree after liming (4.3 – 4.5).  After liming, potential nitrification rates increased significantly throughout the production season in both surface and subsurface soils.   TRFLP analysis of total bacterial and archaeal communities showed significant partitioning of the broader communities with soil depth, pH treatment and time, suggesting that microbial communities respond rapidly to changes and that temporal variation in community structure is an important, if often overlooked, factor in assessing microbial diversity patterns. These changes were greater for bacterial, than archaeal, communities. We then utilised amoA gene microarrays to investigate specific AOA and AOB community responses to temporally induced pH changes.  Despite significant changes to ammonia oxidiser function, we saw only very weak changes in community structure of AOA and AOB, suggesting that over shorter temporal periods soil communities are resilient to environmental change and that niche partitioning of ammonia oxidiser communities is likely to be spatially, rather than temporally, governed.

You are invited to the Sydney Next Generation Sequencing Special Interest Group Meeting,  which will be held at the University of Technology, Sydney.
 
Speakers: 
A/Prof Aaron Darling (ithree Institute, UTS), MinIONs & Hi-C: short vignettes on the state of nanopore sequencing and application of Hi-C to metagenomic sequencing. 
Dr Fabian Buske (Garvan Institute of Medical Research), Title to be advised.
 
When: Thursday 9th October, 4.00pm – 5.00pm followed by drinks and nibbles. 
Where: Room 5.01, Level 5, Building 4, University of Technology, Sydney.
 
Event Date: 
Thursday, October 9, 2014 - 16:00 - 17:00

Dear All,

 

You are invited to the Sydney Next Generation Sequencing Special Interest Group Meeting,  which will be held at the University of Technology, Sydney.

 

Further details are below:

 

Speakers: 

Event Date: 
Wednesday, June 25, 2014 - 18:15 - 18:30
Institution: 
CSIRO
Title: 

Biomes of Australian Soil Environments (BASE)

Abstract: 

The Biomes of Australian Soil Environments (BASE) is a soil microbial diversity database faciliatated by Bioplatforms Australia and currently involving 14 Australian agencies. The BASE project is collecting biodiversity data from Australian soils in the form of amplicon sequences and amplication free metagenomic sequences. Sequence data is accompanied by rich contextual data describing soil physical and chemical attributes, land use, overlying vegetation and climate. All information collected is made publicly available via the BASE database. Thus far BASE has collected approximately 900 samples, with data from over 400 of these being currently available. I will briefly introduce the BASE project and its newly deployed database by describing the sampling and sequencing protocols and demonstrating the databases search capabilities.

Event Date: 
Wednesday, May 28, 2014 - 18:15 - 18:30
Institution: 
CSIRO
Title: 

Cairneyella

Abstract: 

In September 1999, I collected a small heath plant from a large sandstone outcrop near the Murphy’s Glen campsite in the Blue Mountains west of Sydney. This seedling had been growing in just a few centimetres of sand atop the rock. The shallowness of soil meant its root system was perpendicular to the stem, and spread out like a spider’s web from the base. Heath plants have unusual roots; they’re very fine, being only marginally thicker than a human hair. I took the plant back to the laboratories at University of Western Sydney and carefully cut these hair roots up in small pieces. I surface sterilised the pieces in bleach and placed each piece, numbered and its location in the root system recorded, onto an agar plate. From these tiny root pieces grew a host of very slow growing non-spore producing fungi. Most of these fungi were ericoid mycorrhizal (ERM) fungi – these fungi form a symbiosis with heath plants – facilitating their growth in challenging places such as acid bogs, nutrient poor sands and soils rich in metals such as cadium and zinc. Since 1999, I’ve undertaken quite a bit of work on the most abundant ERM fungus from this one seedling, and with the help of various collaborators we have observed the structures it forms in roots of heath plants, how it enhances the growth of heath seedlings and examined its carbon, nitrogen and phosphorus catabolism. It was, and still is, the most studied Australian ericoid mycorrhizal fungus. 
Upon moving to CSIRO in 2007, I left the last six cultures in the fridge in Dr. Peter McGee’s laboratory and it was here that they remained until 2013 when I retrieved them on Peter’s retirement. Just two of the last six survived the long winter. In late 2013, we had some space on an Illumina run with some other samples – and we sequenced the genome of this fungus. We’ve called it ‘Cairneyella’ after the late Professor John W. G. Cairney. There’s still much to learn about Cairneyella – and I’m seeking collaborators who’d like to share these last cultures and further the body of work on this remarkable fungus.

Event Date: 
Wednesday, April 30, 2014 - 18:15 - 18:30
Institution: 
CSIRO
Title: 

Genetic diversity of Group I Clostridium botulinum and Clostridium sporogenes

Abstract: 

Whilst classified as a single bacterial species, Clostridium botulinum comprises a phylogenetically and physiologically diverse collection of organisms. Members of this species are linked together based solely on the production of botulinum neurotoxin (BoNT); amongst most lethal natural toxin produced. Isolates that do not produce BoNT are taxonomically considered a separate species, such as Clostridium sporogenes. Given the species delineation is based solely on an unstable phenetic trait presents increasing challenges in a post-genomic era, particularly with increasing evidence pointing towards the lateral acquisition of BoNT production in many strains. Here, the pan-genome of Group I C. botulinum and C. sporogenes is presented, describing the genetic diversity of these species, highlighting the incongruent taxonomy of these organisms and presenting insights into the acquisition of BoNT within this group.

Event Date: 
Monday, February 24, 2014 - 09:30 - Tuesday, February 25, 2014 - 17:00

 

Registration Closed

24-25 February 2014
The Australian Museum

Microbiology is undergoing a revolution bought about by advances in next-generation DNA sequencing technology.  Researchers are now required to understand an array of bioinformatics principles and tools to interpret the vast amounts of data being generated. Presented by leading Australian researchers, TOAST is a 2-day event aimed at postgraduate students and early career postdocs providing in-depth tutorials encompassing concepts and software available to molecular microbiologists and microbial ecologists including:

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