Honours supervisors and projects

Prof. John Beardall

Ecophysiology of Algae

Telephone: 9905 5611
Email: john.beardall@sci.monash.edu.au

Research in my laboratory is centered on the biochemistry and physiology of aquatic plants, especially algae. I have primary interests in the effects of climate change (elevated CO₂, UV) on algal performance and on applications of infrared biospectroscopy in algal taxonomy and macromolecular composition, though a range of other possibilities are open for Honours projects. Some examples of potential projects are given below. Alternatively, students may wish to suggest a project of their own.

Examples of possible Honours projects in my lab:

1. Effects of climate change (elevated carbon dioxide or UVB radiation) on growth, photosynthesis and macromolecular composition of algae

The global environment is currently experiencing a period of significant change in climate as a result of human activities. Although the planet has experienced very significant variations in climate in the geological past, the rate at which the present changes are occurring is extraordinary. Anthropogenic influences have resulted in an enhancement in atmospheric carbon dioxide levels which will amount to between a 2- to 3-fold increase over the next century and this has already led to a measurable rise in global temperature. At the same time, chlorofluorocarbons (CFCs) are reacting with ozone in the stratosphere, a process that has led to appreciable enhancement of UV-B fluxes to the Earth's surface at high latitudes.

 

Of particular interest are:

• Possible effects of elevated CO₂ on production of extracellular materials by algae on production of extracellular materials by algae. Many algae secrete organic matter to the external environment. If photosynthesis is stimulated by elevated CO₂, proportionately more of the assimilated material might get excreted by cells. This can be passed on to protozoa and bacteria in the surrounding medium. Alternatively, secreted polysaccharide can cause cells to aggregate and sink out of the water column. Both these scenarios are likely to have major consequences for nutrient cycling in marine and freshwater environments.
• Effects of elevated CO₂ and UVB on production of DMS by algae. Dimethyl sulphide (DMS) is a by-product of the use of dimethlyproprionate (DMSP) as a cryoprotectant and osmolyte by algae. DMS production has been linked to increased cloud albedo and feedback mechanisms on global warming. Elevated CO₂ levels may influence the production of secondary metabolites such as DMSP and hence DMS. This project would examine whether this is the case in a range of microalgae and, if so, factors influencing such changes.
• Biochemical and molecular changes associated with oxidative stress in microalgae. Elevated UVB can potentially cause oxidative stress and other forms of damage in algae. This induces changes in levels of enzymes such as superoxide dismutase and ascorbate peroxidase. Elevated CO₂ may modify such stress responses by providing an increase sink for electron transport, and therefore modulate the changes in these and other enzymes. This project would investigate changes in enzyme levels using Western blot and activity analyses as well as examining other stress responses such as production of lipid peroxidation products like malonyldialdehyde

See, e.g.,

Shelly, K., Heraud, P. and Beardall, J. (2002) Nitrogen limitation in Dunaliella tertiolecta Butcher (Chlorophyceae) leads to increased susceptibility to damage by ultraviolet-B radiation but also increased repair capacity. Journal of Phycology 38:1-8.

Beardall, J., Heraud, P., Roberts, S. Shelly, K and Stojkovic, S. (2002) Effects of UV-B radiation on inorganic carbon acquisition by the marine microalga Dunaliella tertiolecta (Chlorophyceae). Phycologia 41: 268-272.

Beardall, J. and Raven J.A. (2004) The potential effects of global climate change on microalgal photosynthesis, growth and ecology. Phycologia 43 : 26-40.

2. Use of biospectroscopy in investigations of algal macromolecular composition and physiology

The responses of higher plants and algae to stress induced by environmental change, such as variations in the availability of nutrients, is aimed at the maintenance of the status quo. Organisms react to change by redistributing resources so that the reproductive and growth potentials are affected as little as possible. This often results in a massive re-organisation of cellular components. The study of the changes in the pools of macromolecules in cells and their quantification, especially in relation to each other, is therefore essential for understanding the response of organisms to alterations in environmental conditions.

Unfortunately, most of the methods used for the assessment of the size of cellular pools of macromolecules are time-consuming, and often require large numbers of cells, which are not always available in microalgal (phytoplankton) populations. However, new and exciting advances in biospectroscopy offer an approach which can provide information on the total biochemical composition and the relative concentration of macromolecules such as proteins, lipids and carbohydrates in the cells. Advances in imaging spectroscopy offer the potential to study the composition of individual cells in a mixed phytoplankton population which has huge implications for our ability to understand the nutrient status of phytoplankton cells and populations in nature. With the imminent commissioning of the Australian Synchrotron at Monash, we will be in the forefront of biospectroscopy in Australia. There are many areas of this research that would be suitable for Honours projects - just 2 such examples are given below

• Use of Raman spectroscopy to study changes in carotenoid content and energy dissipation by algae. Many microalgae use energy dissipation by xanthophyll pigments to avoid photoinhibition by excessive light levels. Raman spectroscopy offers a new, rapid approach to detecting such changes and could lead to exciting new ways to examine the dynamics of algae in changing light fields.
• Investigating algal phylogenetic relationships using spectroscopic information. We have been able to show that biospectroscopic methods provide a robust and rapid approach to discriminate between cyanobacterial species and even strains. We wish to take this analysis further and in conjunction with Dr Wendy Nelson in New Zealand will examine phylogenetic and biogeographical relationships among red algae using a combination of ribosomal RNA sequence analysis and concomitant biospectroscopic approaches.

See e.g.,

Kansiz, M., Heraud, P., Wood, B., Burden, F., Beardall, J. and McNaughton, D. (1999) FTIR spectroscopy as a tool to discriminate between cyanobacterial strains. Phytochemistry, 52: 407-17.

Giordano, M., Kansiz M., Heraud P., Beardall J., Wood B. and McNaughton D. (2001) FT-IR spectroscopy as a novel tool to investigate changes in intracellular macromolecular pools in the marine microalga Chaetoceros muelleri. Journal of Phycology, 37:271-279.

Heraud P, Wood BR, Tobin M, Beardall J and McNaughton, D. (2005). Mapping of nutrient-induced biochemical changes in living algal cells using synchrotron infrared microspectroscopy FEMS Microbiology Letters. 249 : 219–225

3. Use of algal biofilms in remediation of polluted waters

It has been recognised for some time that algal cells accumulate waste materials such as heavy metals, radioisotopes, inorganic and organic compounds, and therefore constitute a basis for novel waste treatment systems. Algae have highly charged cell walls and as a consequence readily bind heavy metal ions to their surface. In addition to binding of metals at charged surfaces (cell walls), algae also have the ability to sequester heavy metals internally at much lower concentrations. As a result they are potentially ideal candidates for the biological removal of heavy metal contamination from industrial wastewater. Wastewater from industry is frequently contaminated with a range of toxicants including heavy metals and organic materials such as phenolics and halogenated hydrocarbons. Removal of such toxicants from the environment is crucial to the sustainable health of Australia’s water systems.

This project will investigate the possibilities for using microalgae growing on solid substrates (i.e. biofilms) for removal of contaminants such as heavy metals from wastewater. A range of species, substrates and growth conditions will be investigated and their efficacy in removal of selected heavy metals measured.

4. Impacts of size on UVB sensitivity of microalgae

The microalgae that comprise the marine phytoplankton contribute up to 45% of the total global annual primary productivity and thereby fix carbon dioxide into organic matter. They are also extremely important in many freshwater systems. However, UVB radiation can have a major impact on microalgal physiology and productivity. It is clear that microalgae have evolved ways of protecting themselves against UVB damage – either by producing UV screening compounds or by having efficient systems to repair damage. 

It has been proposed that smaller cells are more susceptible to UVB than larger cells if both types have similar concentrations of UV screening compounds as the larger cells would present a longer path-length for UV absorption. However, there is only scanty evidence for this in the literature. This project would set out to test the hypothesis that small cells are more susceptible to UV damage than large cells through measurements of UVB damage to the photosynthetic apparatus and raises a number of other questions:

Do small and large cells of related species (or colonial vs single cells of the same species) have similar concentrations of UV screening compounds?

If smaller cells are less able to screen out UVB, can they survive by enhancing rates of repair processes?

See: 

Beardall, J. and Raven J.A. (2004)  The potential effects of global climate change on microalgal photosynthesis, growth and ecology. Phycologia 43: 31-45.

Shelly, K., Heraud, P. and Beardall, J (2002) Nitrogen limitation in Dunaliella tertiolecta Butcher (Chlorophyceae) leads to increased susceptibility to damage by ultraviolet-B radiation but also increased repair capacity. Journal of  Phycology 38: 1-8.

Beardall J, Stojkovic S. 2006. Microalgae under global environmental change: implications for growth and productivity, populations and trophic flow. Science Asia 32:1-10.

Beardall J, Allen A, Bragg J, Finkel ZV, Flynn KJ, Quigg A, Rees TAV, Richardson AJ and J. A. Raven JA. 2009. Allometry and stoichiometry of unicellular, colonial and multicellular phytoplankton. New Phytologist. 181: 295-309.

5. Studies on the formation of blooms by potentially toxic cyanobacteria and algae

We have a general interest in environmental factors that control growth and bloom formation of algae and cyanobacteria and can offer a range of projects in this area. One such example is given below.

Characterization of changes in developing and germinating akinetes, dormant cells of filamentous cyanobacteria (with Dr Assaf Sukenik, Kinneret Limnological Laboratory)

Akinetes are specialized cells produced by certain genera of filamentous, heterocystous cyanobacteria, as a means of withstanding unfavorable conditions. Akinetes may remain as dormant cells for a long time and then germinate as favorable conditions resume. In many cases the germinating akinetes provide the inoculum for the next season’s population and this may give rise to extensive blooms. The formation of akinetes is associated with changes in many cellular properties including a substantial reduction in the photosynthetic activity and alterations in the composition of the photosynthetic machinery. Such changes can be detected by gel electrophoresis and Western blots of proteins associated with the photosynthetic apparatus and by spectral analyses of the cultures by analyzing their room temperature and low temperature (77K) fluorescence properties. More detailed studies of differentiation and germination processes of akinetes are proposed by implementing a Laser Confocal Scanning Microscope (LCSM) available at Monash Micro Imaging (MMI) unit. This approach is expected to show variations among cells of an individual filament and to segregate the mature akinete population as well as the germinating akinetes.

6. Impacts of different nitrogen sources on growth of coccolithophores

Coccolithophores are an extremely important group of marine microalgae. They form huge blooms in the world’s oceans and are responsible for considerable drawdown on carbon both as organic material and as inorganic calcium carbonate scales that cover the cell surface. Accordingly they are extremely important in terms of the global carbon cycle.

Recent work has suggested that large parts of the world’s oceans will become more stratified as a consequence of global warming. This in turn will make the surface waters, where coccolithophorids thrive, more nutrient limited and considerable attention has been paid to the way these organisms adapt to low inorganic nutrient (especially N) levels. However, recent work has suggested that at last one significant coccolithophorid species, Emiliania huxleyi, can utilize organic nitrogen sources such as amino acids as well as inorganic forms such as nitrate and ammonia.

This project would examine the capacity of a range of distinct Southern Hemisphere isolates of E. huxleyi and other coccolithophores to grow and calcify using a range of nitrogen sources. This information will be extremely useful in our attempts to model the impacts of global change on oceanic productivity and the potential of E.hux strains to form blooms with different nitrogen sources and levels under climate change scenarios.

See:

Suzanne L. Strom S.L and   Bright KJ (2009) Inter-strain differences in nitrogen use by the coccolithophore Emiliania huxleyi, and consequences for predation by a planktonic ciliate. Harmful Algae 8 (2009) 811–816

7. Algal Biotechnology

The Beardall lab has links with the algal biotechnology arm of the biodiesel company Energetix.

For appropriately motivated students a number of projects are available that would be centred on the use of microalgae as a source of material for biodiesel and CO₂ bioremediation. Students might be expected to spend some time at the company’s laboratory at Laverton, as well as at Monash.

8. Are epiphytic algae a net source or sink of nitrogen in wetlands?

Co supervisors: Dr. Mike Grace, Dr Perran Cook (Water Studies Centre, School of Chemistry)

This project is best suited to a mid-year intake

Eutrophication is caused by excess nitrogen and phosphorus entering our waterways and is a major threat to aquatic ecosystems, causing excess algal growth which ultimately leads to a loss of amenity and ecological integrity. Denitrification is a crucial nitrogen cycling pathway because it removes bioavailable nitrogen from aquatic ecosystems and is thus an ecologically important process because it can remove excess nitrogen from anthropogenic sources. Denitrification is an obligately anaerobic process and to date, most studies of denitrification have focused on the sediment. Recent measurements have shown that algal growths colonizing hard substrates also have high denitrification rates. Paradoxically, epiphytic algae may also be significant source of nitrogen through the process of N2 fixation if cyanobacteria are present. This project will investigate the relative important of these two processes in a selection of water treatment wetlands around Melbourne.

 

Beardall Lab

More details of our research interests are given at my lab's website:
http://www.biolsci.monash.edu.au/staff/beardall/index.html