A programmed response precedes cell lysis and death in a mat-forming cyanobacterium

Abstract

Phycocyanin is a natural 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. This response explains the high turnover rates of cyanobacterial cells observed in soda lakes. Cells of Arthrospira platensis (Spirulina), currently used worldwide 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, enabling displacement of current artificial blue colourants associated with adverse health effects.

Viral diversity and dynamics and CRISPR-Cas-mediated immunity in a robust alkaliphilic cyanobacterial consortium

“…Eleven metagenomic data sets were used for this study as described in Table S1. These included four metagenomes from the soda lakes (Good Enough Lake [GLM], Deer Lake [DLM], Probe Lake [PLM], and Last Chance [LCM]) ( 26 ), six metagenomes of the laboratory photobioreactor cultures (Year 0, Year 1, and Year 2) ( 23 , 24 , 39 ), and one complete genome of Candidatus Phormidium alkaliphilum ( 23 ). In all analyses, the Year 1 metagenomic assembly was used as a reference point to compare other data sets to.…”

“…The soda lake metagenomes are available at GLM: SAMN10093824 , DLM: SAMN10093822 , PLM: SAMN10093823 , and LCM: SAMN10093821 ( 26 ). The Photobioreactor metagenomes are available at SAMN37413825 , SAMN17969417 , SAMN17969418 , SAMN17969419 , SAMN17969420 , SAMN17264972 ( 39 ). The complete genome of Candidatus Phormidium alkaliphilium is available at SAMN17928605 ( 23 ).…”