Project title: Understanding bacterial-mediated aggregation of microalgae in the environment and for biotechnology
Supervisors: Prof. Justin Seymour and Dr. Bojan Tamburic
Evidence for the highly-complex and intimate association between microalgae and bacteria suggests that interactions between these two microorganisms is critical to several ecological and biotechnological processes. The widespread occurrence of microalgal-bacterial aggregation in the natural environment has driven detailed observational research into the changes in bacterial community composition within an ecological context. In natural aquatic ecosystems, these interactions have important implications for primary productivity, the control of harmful algal blooms and global carbon cycling.
It is widely recognised that microalgae-bacteria interactions are critical to numerous ecological processes. As such, incorporating existing knowledge about bacterial-derived aggregation of microalgae in the natural environment into laboratory settings may bridge the gap between ecology and biotechnology. The incorporation of elements of microalgae-bacteria interactions into mass cultivation of microalgae has been proposed as a way to improve yields and reduce costs.
At this time, the mechanisms driving bacterial-mediated microalgal aggregation are poorly understood. With a new suite of genomic and biochemical tools now available, an open challenge is to elucidate species-specific interactions and their underlying mechanisms within the context of bacterial-mediated aggregation of microalgae. Therefore, integrating both in vitro and in situ studies will further increase our understanding of the microalgae-bacteria interactions at the microscale and at the global scale.
The aim of this study is to first identify bacterial species that can aggregate the biotechnologically relevant microalga Nannochloropsis oculata, and the ecologically important microalga Thalassiosira weissflogii. To also compare the bioflocculation capacity of each bacterium and determine appropriate conditions for efficient bioflocculation of both microalgae species.
This study will also aim to investigate the underlying mechanisms driving bacterial-mediated microalgal aggregation in laboratory-based experiments and subsequently screen for their presence during natural algal bloom-associated aggregation events.
The knowledge gathered by addressing these aims is required to better increase and refine our understanding of the role of bacteria in aggregate formation and sinking. This information is vital to understanding how microalgae-bacteria interactions in the ocean impact larger biogeochemical processes. Integrating knowledge of ecologically relevant aggregation processes with knowledge gained from laboratory experiments will potentially inform microalgal harvesting and production processes. The incorporation of microalgae-bacteria interactions in aggregation processes for biotechnological applications is of interest, as it could be an important strategy to address this major bottleneck in microalgae production.
Tran, N. A. T., Seymour, J. R., Siboni, N., Evenhuis, C. R., Tamburic, B (2017) Photosynthetic carbon uptake induces autoflocculation of the marine microalga Nannochloropsis oculata. Algal Research, 26:302–311.
Tran, N. A. T., Padula, M. P., Evenhuis, C. R., Commault, A. S., Ralph, P. J., & Tamburic, B. (2016). Proteomic and biophysical analyses reveal a metabolic shift in nitrogen deprived Nannochloropsis oculata. Algal Research, 19: 1–11.
Tamburic, B., Szabó, M., Tran, N. A. T., Larkum, A. W. D., Suggett, D. J., & Ralph, P. J. (2014). Action spectra of oxygen production and chlorophyll a fluorescence in the green micro alga Nannochloropsis oculata. Bioresource Technology, 169: 320–327.