Growth Promoting Effects of a Bacterial Consortium on a Lipid Producing Algae Strain

Photosynthetic microalgae offer promising opportunities for biodiesel production due to their high growth rates and triacylglycerol (TAG) lipid synthesis. I am currently studying the growth characteristics of one such marine algae, a Chlorella strain C596. Previously, it was found that strain C596 is not axenic but contains a consortium of background bacteria. Upon removing the majority of these bacteria, the algae showed a reduced growth rate compared to its co-culture counterpart, indicating that the bacterial background could play a role in the increased growth rate of the co-cultured Chlorella strain C596. The goal of my project was to study the mechanisms by which this interaction is facilitating the increased growth rate of the Chlorella strain C596. The recovery of growth was measured in resuspensions of partially purified Chlorella strain C596 in media with the co-culture bacteria present, and in media containing only the bacterially- produced growth factors. Results of both experimental scenarios indicated that presence of growth factors alone could be sufficient to recover the maximal growth rates associated with the original culture, but that the reintroduction of the microbial community was necessary and sufficient for growth rate recovery. Lastly, as proper separation of the bacteria from the algae is a significant step in understanding the interactions between the two, a microfluidic H-Filter device was designed for potential separation of the algae from the bacteria.Dr. Beth Ahne