Outdoor continuous cultivation of self-settling marine cyanobacterium chroococcidiopsis sp.

Abstract

Spontaneous settling of certain aggregating microalgae or cyanobacteria could potentially alleviate the energy requirement in biomass harvesting. A locally isolated floc-forming marine cyanobacteria, Chroococcidiopsis sp., was initially grown indoor to study its self-settling efficiency; 97% of the biomass settled spontaneously in 1 h. Later, the strain was grown in outdoor raceway tanks (1 square meter) for 70 d. Every alternative day, 50% of the culture was harvested by self-settling, and the supernatant was recycled back to the tank. Average biomass productivities for the strain was 16.08 g/m2/d. The biomass had an average 2.26% water extractable phycobiliproteins that comprised of both phycocyanin (11.4 mg/g) and phycoerythrin (10.6 mg/g). Since Chroococcidiopsis sp. biomass can be harvested very efficiently, it would reduce the energy and cost of biomass production which are deemed necessary for microalgal animal feed and biofuel applications. Furthermore, its ability to produce high-value pigments will also make it economically very attractive from biorefinery approach. Copyright 2018, Mary Ann Liebert, Inc. 2018.