Elucidating the picocyanobacteria salinity divide through ecogenomics of new freshwater isolates

作者：Pedro J. Cabello‐Yeves, Cristiana Callieri, Antonio Picazo, Lena Schallenberg, Paula Huber, Juan J. Roda‐Garcia, Maciej Bartosiewicz, О. И. Белых, И. В. Тихонова, Alberto Torcello-Requena, Paula Martin De Prado, Richard J. Puxty, Andrew Millard, Antonio Camacho, Francisco Rodríguez‐Valera, David J. Scanlan · 发表于：BMC Biology · 年份：2022 · DOI：10.1186/s12915-022-01379-z · 被引用次数：33 · 研究领域：Microbial Community Ecology and Physiology、Genomics and Phylogenetic Studies、Photosynthetic Processes and Mechanisms

BACKGROUND: Cyanobacteria are the major prokaryotic primary producers occupying a range of aquatic habitats worldwide that differ in levels of salinity, making them a group of interest to study one of the major unresolved conundrums in aquatic microbiology which is what distinguishes a marine microbe from a freshwater one? We address this question using ecogenomics of a group of picocyanobacteria (cluster 5) that have recently evolved to inhabit geographically disparate salinity niches. Our analysis is made possible by the sequencing of 58 new genomes from freshwater representatives of this group that are presented here, representing a 6-fold increase in the available genomic data. RESULTS: Overall, freshwater strains had larger genomes (≈2.9 Mb) and %GC content (≈64%) compared to brackish (2.69 Mb and 64%) and marine (2.5 Mb and 58.5%) isolates. Genomic novelties/differences across the salinity divide highlighted acidic proteomes and specific salt adaptation pathways in marine isolates (e.g., osmolytes/compatible solutes - glycine betaine/ggp/gpg/gmg clusters and glycerolipids glpK/glpA), while freshwater strains possessed distinct ion/potassium channels, permeases (aquaporin Z), fatty acid desaturases, and more neutral/basic proteomes. Sulfur, nitrogen, phosphorus, carbon (photosynthesis), or stress tolerance metabolism while showing distinct genomic footprints between habitats, e.g., different types of transporters, did not obviously translate into major functionality diff...