Isolation and biogeography of the oligotrophic ocean diazotroph, Crocosphaera waterburyi nov. sp.

Marine N2-fixing cyanobacteria, including the unicellular genus Crocosphaera, are considered keystone species in marine food webs. Crocosphaera are globally distributed and provide new sources of nitrogen and carbon, which fuel oligotrophic microbial communities and upper trophic levels. Despite their ecosystem importance, only one pelagic, oligotrophic, phycoerythrin-rich species, Crocosphaera watsonii, has ever been identified and characterized as widespread.

Spatial and Temporal Resolution of Cyanobacterial Bloom Chemistry Reveals an Open-Ocean as a Talented Producer of Specialized Metabolites.

While the ecological role that sp. play in nitrogen fixation has been widely studied, little information is available on potential specialized metabolites that are associated with blooms and standing stock colonies. While a collection of biological material from a bloom event from North Padre Island, Texas, in 2014 indicated that this species was a prolific producer of chlorinated specialized metabolites, additional spatial and temporal resolution was needed.

Dual thermal ecotypes coexist within a nearly genetically identical population of the unicellular marine cyanobacterium .

The extent and ecological significance of intraspecific functional diversity within marine microbial populations is still poorly understood, and it remains unclear if such strain-level microdiversity will affect fitness and persistence in a rapidly changing ocean environment. In this study, we cultured 11 sympatric strains of the ubiquitous marine picocyanobacterium isolated from a Narragansett Bay (RI) phytoplankton community thermal selection experiment. Thermal performance curves revealed selection at cool and warm temperatures had subdivided the initial population into thermotypes with pronounced differences in maximum growth temperatures.

Metagenome-Assembled Genomes from Photo-Oxidized and Nonoxidized Oil-Degrading Marine Microcosms.

We performed deep metagenomic sequencing on hydrocarbon-degrading marine microcosms designed to experimentally determine the effect of photo-oxidation on oil biodegradation dynamics. Assembly, binning, and dereplication yielded 73 unique metagenome-assembled genomes (MAGs) from 6 phyla, of which 61 are predicted to be over 90% complete.

Importance of mobile genetic element immunity in numerically abundant Trichodesmium clades.

The colony-forming cyanobacteria Trichodesmium spp. are considered one of the most important nitrogen-fixing genera in the warm, low nutrient ocean. Despite this central biogeochemical role, many questions about their evolution, physiology, and trophic interactions remain unanswered.

Metagenome-Assembled Genome of an Alphaproteobacterium Isolated from an HetDA Enrichment from the North Pacific Subtropical Gyre.

Here, we present HetDA_MAG_SS10, a metagenome-assembled genome (MAG) from an enrichment of a heterocystous diazotroph originally living in association with spp. obtained near Station ALOHA in the North Pacific Ocean. HetDA_MAG_SS10, an alphaproteobacterium in the order , is proposed to be photoheterotrophic via rhodopsin and has the potential for dimethylsulfoniopropionate (DMSP) demethylation.

Metagenome-Assembled Genome HetDA_MAG_MH13 of the Family , from a Marine N2-fixing Cyanobacterial Enrichment Culture.

Here, we present a draft genome in the order and family . This draft genome comes from an enrichment of a heterocystous, cyanobacterial diazotroph (HetDA) that was originally living in association with species. This organism is proposed to be an anoxygenic phototroph capable of dissimilatory nitrate reduction to ammonia (DNRA).

Metagenome-Assembled Genome of a Novel Epibiont of a Heterotrophic Diazotroph.

Here, we describe the metagenome-assembled genome (MAG) HetDA_MAG_SS2, in the family . It was found in association with a HetDA cyanobiont isolated from a Station ALOHA colony. Annotation suggests that HetDA_MAG_SS2 is a chemoorganoheterotroph with the potential for lithoheterotrophy, containing genes for aerobic respiration, mixed acid fermentation, dissimilatory nitrate reduction to ammonium, and sulfide oxidation.

Genome Sequence of the Euphotic Hawaiian Gammaproteobacterium HetDA_MAG_MS8, in the Order , Family , Genus .

We present a metagenome-assembled genome (MAG), HetDA_MAG_MS8, that was determined to be unique via relative evolutionary divergence (RED) scores and average nucleotide identity (ANI) values. HetDA_MAG_MS8 is in the order , genus , and was assembled from a heterocytous cyanobiont enrichment from the Hawaii Ocean Time Series. HetDA_MAG_MS8 is predicted to be a facultative, aerobic, anoxygenic photolithoheterotroph that has the potential for sulfide oxidation and dimethylsulfoniopropionate (DMSP) synthesis.

Metagenome-Assembled Genome of a Bacterium, HetDA_MAG_MS6, Isolated from a Consortium from Station ALOHA.

Here, we describe the metagenome-assembled genome (MAG) HetDA_MAG_MS6. HetDA_MAG_MS6 was obtained from an enrichment of the heterocystous diazotroph HetDA, which was isolated near Station ALOHA. The MAG was placed in the family and is predicted to be a chemoorganoheterotroph with the potential for ammonia uptake, phosphonate transport, and sulfolipid biosynthesis.

Genome Sequence of a Heterocystous Diazotroph Isolated from a Consortium from the North Pacific Subtropical Gyre.

Diazotrophic cyanobacteria play a vital role in the nitrogen influx of the global marine ecosystem. In July 2010, colonies of spp. were picked near Station ALOHA in the oligotrophic North Pacific Subtropical Gyre, and a novel heterocystous diazotroph (strain HetDA_MAG_MS3) belonging to the genus was found living in close association; it was cultured and sequenced.

Microbial functional diversity across biogeochemical provinces in the central Pacific Ocean.

Enzymes catalyze key reactions within Earth's life-sustaining biogeochemical cycles. Here, we use metaproteomics to examine the enzymatic capabilities of the microbial community (0.2 to 3 µm) along a 5,000-km-long, 1-km-deep transect in the central Pacific Ocean.

Molecular mechanisms underlying iron and phosphorus co-limitation responses in the nitrogen-fixing cyanobacterium Crocosphaera.

In the nitrogen-limited subtropical gyres, diazotrophic cyanobacteria, including Crocosphaera, provide an essential ecosystem service by converting dinitrogen (N) gas into ammonia to support primary production in these oligotrophic regimes. Natural gradients of phosphorus (P) and iron (Fe) availability in the low-latitude oceans constrain the biogeography and activity of diazotrophs with important implications for marine biogeochemical cycling. Much remains unknown regarding Crocosphaera's physiological and molecular responses to multiple nutrient limitations.

Genome Sequence of sp. Strain LA31, Isolated from a Temperate Estuary.

Cluster 5 species are widely acknowledged for their broad distribution and biogeochemical importance. In particular, subcluster 5.2 strains inhabit freshwater, estuarine, and marine environments but are understudied, compared to other subclusters.

Dynamic diel proteome and daytime nitrogenase activity supports buoyancy in the cyanobacterium Trichodesmium.

Cyanobacteria of the genus Trichodesmium provide about 80 Tg of fixed nitrogen to the surface ocean per year and contribute to marine biogeochemistry, including the sequestration of carbon dioxide. Trichodesmium fixes nitrogen in the daylight, despite the incompatibility of the nitrogenase enzyme with oxygen produced during photosynthesis. While the mechanisms protecting nitrogenase remain unclear, all proposed strategies require considerable resource investment.

Why Environmental Biomarkers Work: Transcriptome-Proteome Correlations and Modeling of Multistressor Experiments in the Marine Bacterium .

Ocean microbial communities are important contributors to the global biogeochemical reactions that sustain life on Earth. The factors controlling these communities are being increasingly explored using metatranscriptomic and metaproteomic environmental biomarkers. Using published proteomes and transcriptomes from the abundant colony-forming cyanobacterium (strain IMS101) grown under varying Fe and/or P limitation in low and high CO, we observed robust correlations of stress-induced proteins and RNAs (i.

Alphaproteobacteria facilitate Trichodesmium community trimethylamine utilization.

In the surface waters of the warm oligotrophic ocean, filaments and aggregated colonies of the nitrogen (N)-fixing cyanobacterium Trichodesmium create microscale nutrient-rich oases. These hotspots fuel primary productivity and harbour a diverse consortium of heterotrophs. Interactions with associated microbiota can affect the physiology of Trichodesmium, often in ways that have been predicted to support its growth.

Mechanisms and heterogeneity of in situ mineral processing by the marine nitrogen fixer Trichodesmium revealed by single-colony metaproteomics.

The keystone marine nitrogen fixer Trichodesmium thrives in high-dust environments. While laboratory investigations have observed that Trichodesmium colonies can access the essential nutrient iron from dust particles, less clear are the biochemical strategies underlying particle-colony interactions in nature. Here we demonstrate that Trichodesmium colonies engage with mineral particles in the wild with distinct molecular responses.

DMSP synthesis genes distinguish two types of DMSP producer phenotypes.

Dimethylsulfoniopropionate (DMSP) is an important organic carbon and sulfur source in the surface ocean that fuels microbial activity and significantly impacts Earth's climate. After three decades of research, the cellular role(s) of DMSP and environmental drivers of production remain enigmatic. Recent work suggests that cellular DMSP concentrations, and changes in these concentrations in response to environmental stressors, define two major groups of DMSP producers: high DMSP producers that contain ≥ 50 mM intracellular DMSP and low DMSP producers that contain < 50 mM.

Metagenome-Assembled Genome Sequence of Aphanizomenon flos-aquae Strain Clear-A1, Assembled from an Enrichment Culture.

is a significant harmful algal bloom-forming cyanobacterial species. Here, we report the draft genome for a strain of (Clear-A1) from a harmful algal bloom enrichment culture. This metagenome-assembled genome (MAG) sequence comprises 4,452,466 bp in 60 contigs with a GC content of 37.

Metagenome-Assembled Genome Sequence of Dolichospermum circinale Strain Clear-D4, Assembled from a Harmful Cyanobacterial Bloom Enrichment Culture.

(formerly ) is a significant harmful algal bloom species. We report the draft metagenome-assembled genome (MAG) for a strain of (Clear-D4) obtained from an enrichment culture. The genome sequence comprises 5,029,933 bp in 560 contigs with a GC content of 37%.

Metagenome-Assembled Genome Sequence of sp. Strain Clear-D1, Assembled from a Cyanobacterial Enrichment Culture.

We report the metagenome-assembled genome sequence of a sp. binned from a cyanobacterial enrichment culture. The genome contains 39 contigs comprising 2.

Metagenome-Assembled Genome Sequence of Bacterium Strain Clear-D3, Assembled from a Consortium from Clear Lake, California.

Here, we report the metagenome-assembled genome sequence of a bacterium strain, Clear-D3, that was reconstructed from a cyanobacterial enrichment from a eutrophic lake. The draft genome sequence shows evidence of an anoxygenic photoautotrophic lifestyle. Other potential capabilities include aerobic heterotrophy, flagellar motility, chemotaxis, and utilization of complex C-P compounds.

Metagenome-Assembled Genome Sequence of Bacterium Strain Clear-D13, Assembled from a Harmful Algal Bloom Enrichment Culture.

Metagenomic sequencing of a enrichment culture resulted in the assembly of several cocultured metagenome-assembled genomes (MAGs). One MAG was affiliated with the class and included 5,724,991 bp in 127 contigs with a GC content of 48.4%.

Long-Term m5C Methylome Dynamics Parallel Phenotypic Adaptation in the Cyanobacterium Trichodesmium.

A major challenge in modern biology is understanding how the effects of short-term biological responses influence long-term evolutionary adaptation, defined as a genetically determined increase in fitness to novel environments. This is particularly important in globally important microbes experiencing rapid global change, due to their influence on food webs, biogeochemical cycles, and climate. Epigenetic modifications like methylation have been demonstrated to influence short-term plastic responses, which ultimately impact long-term adaptive responses to environmental change.