Among the thousands of species that comprise marine bacterioplankton communities, most remain functionally obscure. One key cosmopolitan group in this understudied majority is the OM252 clade of
. ...Although frequently found in sequence data and even previously cultured, the diversity, metabolic potential, physiology, and distribution of this clade has not been thoroughly investigated. Here, we examined these features of OM252 bacterioplankton using a newly isolated strain and genomes from publicly available databases. We demonstrated that this group constitutes a globally distributed novel genus ("
Halomarinus"), sister to
, comprising two subclades and multiple distinct species. OM252 organisms have small genomes (median, 2.21 Mbp) and are predicted obligate aerobes capable of alternating between chemoorganoheterotrophic and chemolithotrophic growth using reduced sulfur compounds as electron donors. Subclade I genomes encode genes for the Calvin-Benson-Bassham cycle for carbon fixation. One representative strain of subclade I, LSUCC0096, had extensive halotolerance and a mesophilic temperature range for growth, with a maximum rate of 0.36 doublings/h at 35°C. Cells were curved rod/spirillum-shaped, ∼1.5 by 0.2 μm. Growth yield on thiosulfate as the sole electron donor under autotrophic conditions was roughly one-third that of heterotrophic growth, even though calculations indicated similar Gibbs energies for both catabolisms. These phenotypic data show that some "
Halomarinus" organisms can switch between serving as carbon sources or sinks and indicate the likely anabolic cost of lithoautotrophic growth. Our results thus provide new hypotheses about the roles of these organisms in global biogeochemical cycling of carbon and sulfur.
Marine microbial communities are teeming with understudied taxa due to the sheer numbers of species in any given sample of seawater. One group, the OM252 clade of
, has been identified in gene surveys from myriad locations, and one isolated organism has even been genome sequenced (HIMB30). However, further study of these organisms has not occurred. Using another isolated representative (strain LSUCC0096) and publicly available genome sequences from metagenomic and single-cell genomic data sets, we examined the diversity within the OM252 clade and the distribution of these taxa in the world's oceans, reconstructed the predicted metabolism of the group, and quantified growth dynamics in LSUCC0096. Our results generate new knowledge about the previously enigmatic OM252 clade and point toward the importance of facultative chemolithoautotrophy for supporting some clades of ostensibly "heterotrophic" taxa.
Neuroinflammation is a complex integration of the responses of all cells present within the CNS, including the neurons, macroglia, microglia and the infiltrating leukocytes. The initiating insult, ...environmental factors, genetic background and age/past experiences all combine to modulate the integrated response of this complex neuroinflammatory circuit. Here, we explore how these factors interact to lead to either neuroprotective versus neurotoxic inflammatory responses. We specifically focus on microglia and astrocytic regulation of autoreactive T cell responses.
Metagenomic sequencing of a
Dolichospermum circinale
enrichment culture resulted in the assembly of several cocultured metagenome-assembled genomes (MAGs). One MAG was affiliated with the class
...Kappabacteriales
and included 5,724,991 bp in 127 contigs, with a GC content of 48.4%.
ABSTRACT
Metagenomic sequencing of a
Dolichospermum circinale
enrichment culture resulted in the assembly of several cocultured metagenome-assembled genomes (MAGs). One MAG was affiliated with the class
Kapabacteriales
and included 5,724,991 bp in 127 contigs with a GC content of 48.4%.
Bacterial characterization is an important aspect of microbiology that includes experimentally determining growth rates, environmental conditions conducive to growth, and the types of energy sources ...microorganisms can use. Researchers use this information to help understand and predict an organism’s ecological distribution and environmental functions. Microbiology students generally conduct bacterial characterization experiments in their coursework; however, they are frequently restricted to model organisms without ecological relevance and already well-studied physiologies. We present a course-based undergraduate research experience (CURE) curriculum to involve students in characterization of previously untested, ecologically relevant aquatic free-living bacteria (bacterioplankton) cultures to identify the usable nutrient substrates, as well as the temperature and salinity ranges conducive to growth. Students use these results to connect their organism’s physiology to the isolation environment. This curriculum also exposes students to advanced microbiology methods such as flow cytometry for measuring cell concentrations, teaches them to use the programming language R for data plotting, and emphasizes scientific communication through writing, speaking, poster creation/presentation, and social media. This CURE is an attractive introduction to scientific research and was successfully tested with 187 students in three semesters at two different universities. Students generated reproducible growth data for multiple strains across these different deployments, demonstrating the utility of the curriculum for research support.
Here, we present the complete genome sequence of
Marinobacterium
sp. strain LSUCC0821, isolated from the coastal Gulf of Mexico with artificial seawater using high-throughput dilution-to-extinction ...(DTE) cultivation. The 2.36-Mbp circularized genome sequence has 2,231 predicted genes, a 91.5% coding density, and a GC content of 47.8%.
ABSTRACT
Here, we present the complete genome sequence of
Marinobacterium
sp. strain LSUCC0821, isolated from the coastal Gulf of Mexico with artificial seawater using high-throughput dilution-to-extinction (DTE) cultivation. The 2.36-Mbp circularized genome sequence has 2,231 predicted genes, a 91.5% coding density, and a GC content of 47.8%.
Here, we report the metagenome-assembled genome sequence of a
Rhodobacteraceae
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.
ABSTRACT
Here, we report the metagenome-assembled genome sequence of a
Rhodobacteraceae
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.
Dolichospermum circinale
(formerly
Anabaena circinale
) is a significant harmful algal bloom species. We report the draft metagenome-assembled genome (MAG) sequence for a strain of
D. circinale
...(Clear-D4) obtained from an enrichment culture. The genome sequence comprises 5,029,933 bp in 560 contigs with 37% GC content.
ABSTRACT
Dolichospermum circinale
(formerly
Anabaena circinale
) is a significant harmful algal bloom species. We report the draft metagenome-assembled genome (MAG) for a strain of
D. circinale
(Clear-D4) obtained from an enrichment culture. The genome sequence comprises 5,029,933 bp in 560 contigs with a GC content of 37%.
We report the metagenome-assembled genome sequence of a
Vulcanococcus
sp. binned from a cyanobacterial enrichment culture. The genome contains 39 contigs comprising 2.96 Mbp and is estimated as 100% ...complete, with a GC content of 63.9% and 3,261 predicted coding genes.
ABSTRACT
We report the metagenome-assembled genome sequence of a
Vulcanococcus
sp. binned from a cyanobacterial enrichment culture. The genome contains 39 contigs comprising 2.96 Mbp and is estimated as 100% complete, with a GC content of 63.9% and 3,261 predicted coding genes.
Aphanizomenon flos-aquae
is a significant harmful algal bloom forming cyanobacterial species. Here, we report the draft genome for a strain of
A. flos-aquae
(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 37.1%.
ABSTRACT
Aphanizomenon flos-aquae
is a significant harmful algal bloom-forming cyanobacterial species. Here, we report the draft genome for a strain of
A. flos-aquae
(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 37.1%.
Marine phytoplankton produce ∼10(9) tonnes of dimethylsulfoniopropionate (DMSP) per year(1,2), an estimated 10% of which is catabolized by bacteria through the DMSP cleavage pathway to the ...climatically active gas dimethyl sulfide(3,4). SAR11 Alphaproteobacteria (order Pelagibacterales), the most abundant chemo-organotrophic bacteria in the oceans, have been shown to assimilate DMSP into biomass, thereby supplying this cell's unusual requirement for reduced sulfur(5,6). Here, we report that Pelagibacter HTCC1062 produces the gas methanethiol, and that a second DMSP catabolic pathway, mediated by a cupin-like DMSP lyase, DddK, simultaneously shunts as much as 59% of DMSP uptake to dimethyl sulfide production. We propose a model in which the allocation of DMSP between these pathways is kinetically controlled to release increasing amounts of dimethyl sulfide as the supply of DMSP exceeds cellular sulfur demands for biosynthesis.
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