Stoichiometrically balanced nutrient management using a newly designed nutrient medium for large scale cultivation of Cyanobacterium aponinum

Abstract

Cyanobacteria have tremendous potential to produce bioactive molecules, which makes them a highly lucrative organism for use in industrial applications. In the present study, the first commercial nutrient medium for Cyanobacterium aponinum is developed and a process for large scale cultivation of cyanobacteria is established by combining economical medium, pre-emptive nutrient feeding strategy, and semi-continuous mode (SCM) of cultivation. The parameters measured were growth in terms of OD750 biomass, total nitrogen, nitrate, and phosphorous. Results indicated 13% more biomass yield in urea-phosphoric acid medium (UPA), in comparison to blue-green medium (BG-11). Biomass concentration was 5.3 and 4.7 g L−1 with UPA and BG-11 media, respectively. Urea was found to be a preferred nitrogen source for C. aponinum. Nutrient-dosing studies with UPA medium in SCM of operation resulted in an average daily biomass productivity of ~ 0.44 g L−1 day−1, which is significantly higher than those reported in previous studies. Here, the stoichiometric requirement of nitrogen and phosphorous was found to be 31 mg L−1 and 4.5 mg L−1, respectively. Stoichiometric nutrient addition in SCM resulted in a reduction in nutrient loss in blow down. In addition, the outdoor scale-up studies in flat panel photobioreactors further established the efficacy of UPA medium. Cost analysis of media revealed that UPA medium is 4.4 times less expensive than BG-11 and hence is a suitable and economical medium for large scale cultivation of C. aponinum. Further, this nutrient feeding strategy has wider applications which can be extended to other algal strains and cultivation systems.