(627c) A Novel Symbiotic Biofilm for Algae Growth and Harvesting

Authors: 
Rajendran, A., University of Minnesota
Hu, B., University of Minnesota
Reis, C. E. R., University of Minnesota
Zhang, Y., University of Minnesota
Lin, H., University of Minnesota
Zhang, X., University of Minnesota

Microalgae has the potential to become a substantial driver in the development of a bio-based economy, and has been considered as a promising source for biofuel and bioenergy production, bio-remediation and other high-value bioactive compounds or combination of above. Large-scale applications of microalgae biotechnology is hampered by the current energy-intensive or non-ecofriendly chemical harvest technology; along with the nutrient and water requirements. In this work, we attempt to develop a lichen-type symbiotic biofilm using algae and fungal cultures and also address the cultivation barriers using a synthetic community which will possibly transform the algae cultivation in the future for various applications. Cultures with algae and fungi could be the ideal strain combination for symbiotic biofilm because these two strains don’t compete for the same respiratory gases whereas they complement each other; algae is photoautotropic; and the fungi can utilize wide range of substrates with the history of having wide range of symbiotic functions in the biota.

The lichen-type biofilm formation was studied with various fungal strains and model algae strain C. vulgaris and the factors affecting the process including effect of different matrix for attachment, initial glucose concentration, and biomass distribution at different time interval. The possibility of co-existence of Chlorella vulgaris with various fungal cultures was tested to identify the best strain combination for high algae harvest efficiency. The effect of different matrix type (woven stainless steel mesh, coiled metal matrix, cotton mesh, and cotton-polypropylene composite mesh) and initial glucose concentration (0-10 g/L) on biofilm formation and algae attachment; and kinetics of the process with respect to the algae-fungi cell distribution and total biomass production was estimated. The algae attachment efficiency of 99.0 % and above was achieved in a polymer-cotton composite matrix with low glucose concentration of 2 g L-1 in the growth medium for initiating the fungal growth and agitation intensity of 150 rpm at 27 °C. The ultra-clear water in the flask after removing the biofilm can be used for next batch of algae-fungi culture without any pretreatment or processing with nutrient addition. The existing technologies are economically feasible only to algae production for high-value products as there is a significant cost involved in algae harvest and dewatering. Whereas, the novel microalgae cultivation platform technology is completely different from all the traditional methods and avoids the conventional complex harvesting and processing procedures and propounds the scope for an energy efficient, eco-friendly and cost-effective “lichen” type biofilm, exploring new avenues in the bio-production industry with many potential applications.