The Growth of Algae on Bacteria and its Potential for Industrial Application

Abstract

Algae have diverse nutrition strategies to grow, including utilizing light through phototrophy, taking up dissolved substances through osmotrophy, and ingesting bacteria through phagotrophy. Compared to the many reports on the phototrophic and osmotrophic growths, the phagotrophic growth of algae is much less studied and its potential for industrial application has not been explored. In this research, the growth of the algae species Ochromonas danica on bacteria was investigated, and the potential of the phagotrophic growth for industrial application was discussed. Results show that O. danica was able to grow rapidly on bacteria without light or supplementation of any dissolved substances. The doubling time was 3.5-3.9 h, and the algal biomass yield from bacteria was 41-45%. The produced O. danica cells were rich in lipids, about 35-46% of their dry matter. The phagotrophic growth of algae can be potentially utilized for the treatment of bacteria-rich waste such as waste sludge. With fast bacterial digestion capability, waste sludge digestion rate was largely enhanced. Furthermore, significant amount of organic matter can be converted into lipid-rich algal biomass. The phagotrophic growth can also be exploited to reclaim organic matter from wastewater through a two-stage process, in which bacteria were first grown on wastewater organic matter and then the bacteria were fed to algae for growth. The findings of this research demonstrates great potential of the phagotrophic growth for lipid production and waste treatment.

Keywords: Phagotrophic algae, lipid production, Resource recovery, waste sludge treatment, Wastewater treatment