Please be aware of the following courses being advertised to run at HIE in the next few months. These are a good opportunity to hone your skills in essential and commonly-used science technologies.
1) ‘Data Analysis And Visualization With R' Course - Monday 13th April to Friday 17th April 2015
The R statistical computing environment has become a standard for scientific data analysis, visualization and reproducible research. At the HIE, we offer an introductory course to help you climb the steep learning curve. This five-day course is aimed at postgraduate students and staff, and is for newcomers to R.
UWS staff and students can enrol at no charge.
Information at www.uws.edu.au/rcourse
Photosynthetic Microbial Fuel Cells: From Sunlight to Bioelectricity
Microbial fuel cells (MFCs) harvest electricity from microorganisms capable of catalyzing the conversion of chemical energy in organic compounds into electrical power. As any other fuel cells, MFCs consist of an anode and a cathode chamber connected together by an external circuit. The flow of electrons from the anode to the cathode generates a current. A major limitation for the use of MFCs is their cost per unit of electricity as they often require expensive catalysts, ion-exchange membranes and air-pumps. This presentation describes a photosynthetic biocathode in a sediment-type microbial fuel cell (pMFC) constructed without a proton exchange membrane and exposed to sunlight. The carbon and stainless steel cathode did not contain any catalyst, but was covered in a biofilm composed of a complex community including microalgae and cyanobacteria. The impacts of various parameters, such as temperature and dissolved oxygen, on the performance of sediment-type pMFCs were monitored. We found that higher temperatures lowered the anode potential by boosting the metabolism of the anodic biofilm. The biological production of oxygen in close proximity to the illuminated cathode significantly increased its performance as compared to that achievable with mechanical aeration. However, the photosynthetic biofilms grown in this study did not appear to catalyse oxygen reduction reactions, since a clean electrode, without biofilm, performed equally well. Instead, the reduction of oxygen at the cathode during daytime is likely to follow the peroxide pathway.
The roles of extracellular DNA in bacterial biofilm formation
Bacterial biofilm formation is dependent upon production of extracellular polymeric substances (EPS) mainly composed of polysaccharides, proteins, lipids and extracellular DNA (eDNA). eDNA promotes initial bacterial adhesion, aggregation, biofilm formation in a wide range of bacterial species. In Pseudomonas aeruginosa eDNA is a major component of biofilms and is essential for biofilm formation and stability. P. aeruginosa also produces phenazine an electrochemically active metabolite and phenazine production promotes eDNA release. The relationship between eDNA release and phenazine production is bridged via hydrogen peroxide (H2O2) generation and subsequent H2O2 mediated cell lysis and ultimately release of chromosomal DNA into the extracellular environment as eDNA. Recent investigation showed pyocyanin (a kind of phenazine predominantly produced by P. aeruginosa) binds to eDNA mediated through intercalation of pyocyanin with eDNA. Pyocyanin binding to DNA has significant impacts on DNA properties and also on P. aeruginosa cell surface properties including its hydrophobicity, attractive surface energies physico-chemical interactions and bacterial aggregation.
The Ocean....from the microscale
At a time when microbial ecology is largely traveling along genomic roads, we cannot forget that the functions and services of microbes depend greatly on their behaviors, encounters, and interactions with their environment. New technologies, including microfluidics, high-speed video-microscopy and image analysis, provide a powerful opportunity to spy on the lives of microbes, directly observing their behaviors at the spatiotemporal resolution most relevant to their ecology. I will illustrate this 'natural history approach to microbial ecology' by focusing on marine bacteria, unveiling striking adaptations in their motility and chemotaxis and describing how these are connected to their incredibly dynamic, gradient-rich microenvironments. Specifically, I will present (i) direct evidence for a diverse gallery of microscale microbial hotspots in the ocean; (ii) a new framework for understanding the evolution of microbial diversity in the ocean; and (iii) microfluidic experiments to capture the dramatic chemotactic abilities of bacterial pathogens towards the roiling surface of coral hosts. Through these examples, I hope to show that direct visualization can foster a new layer of understanding in microbial ecology and can help us unlock the ocean's microscale.
Decomposer Microbial Communities Shift from Native Eucalyptus Diversity to Pine-type Diversity in Eucalypt Forests Fragmented by Pine Plantations
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.
Genome evolution in Blattabacterium cuenoti
In addition to harbouring intestinal symbionts, some animal species also possess intracellular symbiotic microbes. The relative contributions of gut-resident and intracellular symbionts to host metabolism, and how they coevolve are not well understood. Cockroaches and the termite Mastotermes darwiniensis present a unique opportunity to examine the evolution of spatially separated symbionts, as they harbour gut symbionts and the intracellular symbiont Blattabacterium cuenoti. The genomes of B.cuenoti from M.darwiniensis and the social wood-feeding cockroach Cryptocercus punctulatus are each missing most of the pathways for the synthesis of essential amino acids found in the genomes of relatives from non-wood-feeding hosts. Hypotheses to explain this pathway degradation include: (i) feeding on microbes present in rotting wood by ancestral hosts; (ii) the evolution of high-fidelity transfer of gut microbes via social behaviour. To test these hypotheses, we sequenced the B.cuenoti genome of a third wood-feeding species, the phylogenetically distant and non-social Panesthia angustipennis.We show that host wood-feeding does not necessarily lead to degradation of essential amino acid synthesis pathways in B.cuenoti, and argue that ancestral high-fidelity transfer of gut microbes best explains their loss in strains from M.darwiniensis and C.punctulatus.