Abstract
Cyanobacteria encompass a diverse group of photoautotrophic bacteria with important roles in nature and biotechnology. Here we characterized Candidatus "Phormidium alkaliphilum," an abundant member in alkaline soda lake microbial communities globally. The complete, circular whole-genome sequence of Ca. "P. alkaliphilum" was obtained using combined Nanopore and Illumina sequencing of a Ca. "P. alkaliphilum" consortium. Strain-level diversity of Ca. "P. alkaliphilum" was shown to contribute to photobioreactor robustness under different operational conditions. Comparative genomics of closely related species showed that adaptation to high pH was not attributed to specific genes. Proteomics at high and low pH showed only minimal changes in gene expression, but higher productivity in high pH. Diverse photosystem antennae proteins, and high-affinity terminal oxidase, compared with other soda lake cyanobacteria, appear to contribute to the success of Ca. "P. alkaliphilum" in photobioreactors and biotechnology applications.