Environment

Event Date: 
Wednesday, June 24, 2015 - 18:00 - 18:45
Institution: 
University of Western Australia
Title: 

Microbial life in Movile Cave – an unusual cave ecosystem

Abstract: 

Movile Cave (Mangalia, Romania) is a unique cave ecosystem sustained by in situ chemoautotrophic primary production, analogous to deep-sea hydrothermal vents. The cave has been cut-off from the surface for the past 5.5 million years with the primary energy source coming mainly from hydrogen sulfide and methane released from the thermal fluids. Invertebrates, many of which are endemic to Movile Cave, are isotopically lighter in both carbon and nitrogen than surface organisms, indicating that chemoautotrophic primary production, primarily driven by methane and sulfur oxidizing microorganisms, occurs in the cave. In this talk, I will present our recent work on the microbiology of the Movile Cave ecosystem, with particular emphasis on functional diversity of Bacteria involved in aerobic one-carbon (methane and methylated amine) metabolism. Insights from metagenomic and genomic sequence analyses of the microbial community and isolates, respectively, will be discussed in detail.

Event Date: 
Wednesday, February 25, 2015 - 15:30 - 16:00
Institution: 
University of California Davis
Title: 

Stress, function and community dynamics in wastewater bioreactors

Abstract: 

Biological wastewater treatment plants receive a complex mixture of chemicals and are operated based on principles of general microbial growth kinetics. Regulated effluent criteria determine the extent of treatment required to achieve removal of chemical oxygen demand and nutrients like reduced nitrogen and phophate. Plants are, however, not designed to metabolize specific (micro)pollutants, and the factors influencing the emergence of microbial communities that are tolerant of or have evolved to metabolize and remove toxic compounds are poorly understood. Basic questions in wastewater engineering include ‘What affects the dynamics of wastewater microbial communities?’  and ‘Are communities ever stable and if so does this matter for basic processes like removal of organics and nutrients?’.  
We investigated the impact of defined and sustained chemical stress on wastewater microbial communities and their functions, using the highly toxic and recalcitrant compound 3-chloroaniline (3-CA) as model stressor. Experimental design included replicate bioreactors, sterile synthetic feed, ambient levels of 3-CA, and fixed factors like bioaugmentation and temperature. Process outcomes varied from no removal of 3-CA to complete removal within three weeks. Community changes were dramatic and nitrification was a key function affected by the stressor. Finally, microbial diversity indices based on 16S rRNA gene amplicon sequencing or T-RFLP, combined with influent nutrient concentrations, were used to predict effluent concentrations using support vector regression, a machine learning model. Sensitivity analysis of a preliminary dataset for a full-scale water reclamation plant would suggest that evenness is the most significant input variable for the prediction of soluble COD, nitrate and ammonium concentrations in the effluent. Overall, we show that both detailed analysis of taxonomy and gene expression and general indices of diversity are useful for understanding the link between stable process performance and microbial communities.

Event Date: 
Wednesday, March 26, 2014 - 18:00 - 18:15
Institution: 
UNSW
Title: 

Insights into the stress response of the biomining bacterium Acidithiobacillus ferrooxidans using gene expression and proteomic analysis

Abstract: 

Bioleaching is a simple and effective process used for metal extraction from low grade ores and mineral concentrates using microorganisms. The extraction of some metals such as copper from low grade ore is becoming necessary because of gradual depletion of high grade ore. The traditional methods used for extraction of copper are either Pyrometallurgy or Hydrometallurgy. However both the methods are not environmental friendly. There are many techniques proposed to extract metals but these are not practically suitable, as these requires a very high energy input as well as most of them creates environmental pollution problem, that also rises the cost of environmental protection throughout the world. Therefore, bioleaching is recognizable as the most environmentally friendly method of separating metals since it requires less energy and it reduces the amount of greenhouse gasses released to the atmosphere. Bioleaching is also a fairly simple process that does not require a lot of expertise to operate or complicated machinery.
The most commonly used bacterium in bioleaching is Acidithiobacillus ferrooxidans (former Thiobacillus ferrooxidans) and this is due to its capacity to oxidize metal sulphides. A. ferroxidans is a chemolithotrophic bacterium capable of utilizing ferrous iron or reduced sulphur compounds as the sole source of energy for its growth. It thrives optimally around pH 2.0 and 30ºC. During Bioleaching process, A. ferrooxidans is often subject to changes in the ideal growth pH and temperature, and to nutrients starvation. These changes can affect the bacterial physiology and as a consequence, the efficiency of bioleaching. Then, the stress response of this bacterium subject to heat stress and phosphate starvation has been investigated using different approaches, namely, gene expression and proteomic analysis, Fourier transform infrared spectroscopy (FT-IR), as well as morphological analysis by scanning electron microscopy (SEM).
The results showed that under the tested stress conditions A. ferrooxidans cells suffer elongation, a common stress response in bacteria. Alterations in carbohydrates, phospholipids and phosphoproteins were detected by FT-IR. By proteomic analyses (2-DE and tandem mass spectrometry), many differentially expressed protein spots were visualized and identified as proteins belonging to 11 different functional categories. Indeed, the up-regulated proteins were mainly from the protein fate category. Real time quantitative PCR was employed to analyze changes in the expression patterns of heat shock genes, as well as many other genes encoding proteins related to several functional categories in A. ferrooxidans. Cells were submitted to long-term growth and to heat shock, both at 40°C. The results evidenced that heat shock affected the expression levels of most genes while long-term growth at 40°C caused minimal changes in gene expression patterns – with exception of some iron transport related genes, which were strongly down-regulated. Further bioinformatic analysis indicated a putative transcriptional regulation, by the σ32 factor, in most heat-affected genes. These results evidence that A. ferrooxidans has an efficient range of stress-responses, which explains its ability for biotechnological purposes.
 

Event Date: 
Wednesday, September 25, 2013 - 07:00 - 08:00
Institution: 
Helmholtz Centre for Groundwater Ecology, Munich, Germany
Title: 

Limiting factors for anaerobic aromatic hydrocarbon degradation in contaminated aquifers and oil reservoirs

Abstract: 

 
Biography

  • Rainer Meckenstock studied biology at University of Konstanz, Germany 1985-1990. He finished with a thesis in the group of Prof. Winfried Boss on microbial sugar transport systems (molecular microbiology). He did his PhD at the Swiss Federal Institute of Technology (ETH) in Zürich, Switzerland, with a thesis on biochemistry of light-harvesting complexes of phototrophic bacteria (1990-1993) in the Institute of Molecular Biology and Biophysics with Prof. Zuber. During his post-doc at the Swiss Federal Institute of Environmental Science andTechnology (EAWAG) in the group of Dr. van der Meer in Dübendorf, Switzerland, he developed molecular methods to monitor trichlorobenzene-degrading microorganisms and their degradation activities in the environment (PCR, RT/PCR, in situ hybridisation) (1993-1995). He changed to the investigation of anaerobic degradation of aromatic hydrocarbons in the Microbial Ecology Group of Prof. Bernhard Schink, University of Konstanz, Germany, in 1996. Here, he isolated novel anaerobic BTEX and PAH-degrading organisms and studied the degradation pathways. A new method to study microbial activities in the environment with analysis of stable isotope fractionation was developed. Since 2000 he changed to the Center of Applied Geosciences at the University of Tübingen, Germany, and set up a Geomicrobiology group within the Chair of Environmental Mineralogy (Prof. Stefan Haderlein). Research topics were the anaerobic degradation of mono- and polycyclic aromatic hydrocarbons (BTEX, PAH), isotope fractionation as a means to monitor biodegradation in contaminated groundwaters, limitations of natural attentuation, and the reduction of iron minerals as electron acceptor. Since July 2003, he became the director of the Institute of Hydrology at GSF which changed its name to Institute of Groundwater Ecology at the beginning of 2004. In 2007 he was appointed as a full professor for Groundwater Ecology at the Life Science Center (WZW) of the Technical University of Munich.
Event Date: 
Wednesday, August 28, 2013 - 18:00 - 18:15
Institution: 
CSIRO Canberra
Title: 

Decomposer Microbial Communities Shift from Native Eucalyptus Diversity to Pine-type Diversity in Eucalypt Forests Fragmented by Pine Plantations

Abstract: 

 
The Wog Wog Fragmentation Experiment was started 29 years ago as a collaboration between CSIRO and NSW Forestry and is one of the longest running ecological experiments in the world.  It was designed to study the effects of Pinus radiata plantations on patches of old-growth Eucalyptus forest in terms of overall health as well as plant and insect species diversity.  Early work at the site showed that, in agreement with fragmentation ecology theory, predatory and generally rarer beetles decreased in eucalyptus fragments surrounded by the newly planted pines whereas decomposer and fungus-feeding beetle species increased.  These types of edge-dependant effects penetrated at least 100m into remnant eucalyptus forest fragments.
Recently, there have been a number of new studies on diverse aspects of forest diversity and health at the site.  This recent work has focused on understory plant diversity, long-term ground-dwelling beetle diversity and population dynamics, soil nutrient levels, soil bacterial and fungal diversity, skink and bird diversity, Eucalyptus growth and demographics, and understory light and temperature regimes.  Andrew King’s presentation will focus on the interaction between soil microbial communities, altered soil carbon and nitrogen cycles, and an unexpected increase in Eucalypt growth in response to fragmentation.

JAMS REPORT
Maria-Luisa Gutierrez-Zamora

The JAMS rendezvous this October 31st took place in the fourth floor of the Museum with a magnificent view of Sydney, and began with an ad hoc presentation featuring sulphurous scents and sexy fangs. Katherina Petrou (UTS) initiated us in the science of the sulphur cycle in the oceans and how this process is dominated by the production of dimethylsulfoniopropionate (DMSP) by microalgae and its decomposition into dimethylsulphide (DMS), a strong odorous chemoattractant for a range of marine organisms. In tackling the mystery of how harmful algal blooms disappear, Katherina discovered that DMS produced by the dinoflagellate Alexandrium minutum (causative agent of toxic algal blooms) was the chemical cue for the infection of its parasitoid Parvilucifera sinerae.  An elegant video illustrated how DMS at 300 nM was able to activate the parasitoid spores from a dormant state to leave the sporangium (an infected A. minutum cell) in transit to infect other cells and propagate. Activation only occurred in the range of 30 to 300 nM indicating that the effect was dependent on cell density. Thus, Katherina’s work showed that DMS plays an important role in the biological control of toxic algal blooms in the oceans. Her results contribute to the better understanding of marine chemical ecology.

Event Date: 
Wednesday, November 28, 2012 - 07:00 - 08:00
Institution: 
University of Sydney
Title: 

Biodegradation of dichloroethane by aerobic bacteria at the Botany Industrial Park

Abstract: 

The chlorinated hydrocarbon 1,2-dichloroethane (DCA) is a common pollutant of groundwater, and poses both human and environmental health risks. The Botany Industrial Park in south Sydney is heavily contaminated with DCA and other organochlorines. The main user of the site (Orica Ltd) operates a large groundwater treatment plant (GTP) on site to contain and remediate the DCA-contaminated groundwater. At present, remediation is done by air-stripping and thermal oxidation, but this is very costly and energy-intensive. Orica is interested in alternative technologies for treating the groundwater, including bioremediation. In 2010, a pilot scale membrane bioreactor (MBR) was set up to treat a fraction of the groundwater. The aims of our study were to identify DCA-degrading bacteria and genes in the GTP and on the site at large, define the community structure and ecological successions occurring in the MBR, develop a qPCR for catabolic genes in the DCA biodegradation pathway, and field-test this qPCR assay in the MBR and in a survey of groundwater in monitoring wells on the site. We discovered that DCA-degrading bacteria using a hydrolytic pathway (dhlA/dhlB genes) were widespread and diverse at this site, and that the dhlA gene was carried on a catabolic plasmid. The community in the MBR was dominated by alpha- and beta-proteobacteria, and was highly dynamic, changing dramatically in composition as the percentage of raw groundwater in the feed was increased. By combining dhlA qPCR and 16S pyrosequencing data, we found evidence that thus-far-uncultured species of Azoarcus may play a major role in DCA bioremediation in situ in the MBR.

 
Prepared by Valentina Wong (UNSW PhD student)
On a cold Tuesday night, Adrian Low from University of New South Wales warmed the JAMS audience with his passion on bioremediation of organochlorine contaminated groundwater. Adrian described the discovery of Australia’s first 1,2-dichloroethane (DCA) degrading consortium, AusDCA. His work in the field demonstrated the efficacy and sustainability of using organochlorine respiring bacteria to remediate organochlorine contaminants in situ. He plans to isolate the bacterial species responsible for performing this unique task.

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