Programmed cell death improves sustainability of phycocyanin production from cyanobacteria

Abstract

AbstractPhycocyanin is a blue pigment produced by cyanobacteria and is a valuable compound for food and cosmetic industries. At present, phycocyanin is manufactured with expensive and resource-heavy biotechnology, impeding its widespread use as a blue dye substitute. Here we show that cells of an alkaliphilic cyanobacterium lyse spontaneously in dark incubations mimicking natural soda lake environments, releasing concentrated phycocyanin. Proteogenomics showed that lysis likely resulted from a programmed response triggered by a failure to maintain osmotic pressure in the wake of severe energy limitation. Protein expression data suggested that CRISPR-Cas and toxin antitoxin systems were potentially involved in cell death. Cells ofArthrospira platensis(Spirulina), currently used for phycocyanin production, lyse and release their pigments in the same manner. We propose this natural form of programmed cell death could reduce the costs and resources needed to produce phycocyanin, and eventually provide a new pathway for controlling harmful algal blooms.One-Sentence SummaryFailure to maintain osmotic balance in the dark forces blue-green algae to share their bounty with the world.