Effects of Co-culture on Improved Productivity and Bioresource for Microalgal Biomass Using the Floc-Forming Bacteria Melaminivora Jejuensis

Bacterial and algal floc formation was induced by inoculating three species of wastewater-derived bacteria ( , and ) into algal cultures ( ). Bacterial and algal flocs formed in algal cultures inoculated with and , and these flocs showed higher sedimentation rates than pure algal culture. The floc formed by (4988.46 ± 2589.81 μm) was 10-fold larger than the floc formed by (488.60 ± 226.22 μm), with a three-fold higher sedimentation rate ( , 91.08 ± 2.32% and , 32.55 ± 6.33%). Biomass and lipid productivity were improved with inoculation [biomass, 102.25 ± 0.35 mg/(L·day) and 57.80 ± 0.20 mg/(L·day)] compared with the productivity obtained under pure algal culture conditions [biomass, 78.00 ± 3.89 mg/(L·day) and lipids, 42.26 ± 2.11 mg/(L·day)]. Furthermore, the fatty acid composition of the biomass produced under pure algal culture conditions was mainly composed of C (43.67%) and C (45.99%), whereas the fatty acid composition of the biomass produced by was mainly C (31.80%), C (24.45%), C (20.23%), and C (16.11%). These results suggest the possibility of developing an efficient method for harvesting microalgae using and provide information on how to improve biomass productivity using floc-forming bacteria.