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1.
Appl Environ Microbiol ; 90(6): e0057024, 2024 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-38809046

RESUMO

The complex interactions between bacterioplankton and phytoplankton have prompted numerous studies that investigate phytoplankton microbiomes with the aim of characterizing beneficial or opportunistic taxa and elucidating core bacterial members. Oftentimes, this knowledge is garnered through 16S rRNA gene profiling of microbiomes from phytoplankton isolated across spatial and temporal scales, yet these studies do not offer insight into microbiome assembly and structuring. In this study, we aimed to identify taxa central to structuring and establishing the microbiome of the ubiquitous diatom Asterionellopsis glacialis. We introduced a diverse environmental bacterial community to A. glacialis in nutrient-rich or nutrient-poor media in a continuous dilution culture setup and profiled the bacterial community over 7 days. 16S rRNA amplicon sequencing showed that cyanobacteria (Coleofasciculaceae) and Rhodobacteraceae dominate the microbiome early on and maintain a persistent association throughout the experiment. Differential abundance, co-abundance networks, and differential association analyses revealed that specific members of the family Rhodobacteraceae, particularly Sulfitobacter amplicon sequence variants, become integral members in microbiome assembly. In the presence of the diatom, Sulfitobacter species and other Rhodobacteraceae developed positive associations with taxa that are typically in high abundance in marine ecosystems (Pelagibacter and Synechococcus), leading to restructuring of the microbiome compared to diatom-free controls. These positive associations developed predominantly under oligotrophic conditions, highlighting the importance of investigating phytoplankton microbiomes in as close to natural conditions as possible to avoid biases that develop under routine laboratory conditions. These findings offer further insight into phytoplankton-bacteria interactions and illustrate the importance of Rhodobacteraceae, not merely as phytoplankton symbionts but as key taxa involved in microbiome assembly. IMPORTANCE: Most, if not all, microeukaryotic organisms harbor an associated microbial community, termed the microbiome. The microscale interactions that occur between these partners have global-scale consequences, influencing marine primary productivity, carbon cycling, and harmful algal blooms to name but a few. Over the last decade, there has been a growing interest in the study of phytoplankton microbiomes, particularly within the context of bloom dynamics. However, long-standing questions remain regarding the process of phytoplankton microbiome assembly. The significance of our research is to tease apart the mechanism of microbiome assembly with a particular focus on identifying bacterial taxa, which may not merely be symbionts but architects of the phytoplankton microbiome. Our results strengthen the understanding of the ecological mechanisms that underpin phytoplankton-bacteria interactions in order to accurately predict marine ecosystem responses to environmental perturbations.


Assuntos
Diatomáceas , Microbiota , RNA Ribossômico 16S , Rhodobacteraceae , Diatomáceas/microbiologia , RNA Ribossômico 16S/genética , Rhodobacteraceae/genética , Rhodobacteraceae/classificação , Rhodobacteraceae/fisiologia , Rhodobacteraceae/isolamento & purificação , Fitoplâncton/microbiologia
2.
Proc Natl Acad Sci U S A ; 117(44): 27445-27455, 2020 11 03.
Artigo em Inglês | MEDLINE | ID: mdl-33067398

RESUMO

Unicellular eukaryotic phytoplankton, such as diatoms, rely on microbial communities for survival despite lacking specialized compartments to house microbiomes (e.g., animal gut). Microbial communities have been widely shown to benefit from diatom excretions that accumulate within the microenvironment surrounding phytoplankton cells, known as the phycosphere. However, mechanisms that enable diatoms and other unicellular eukaryotes to nurture specific microbiomes by fostering beneficial bacteria and repelling harmful ones are mostly unknown. We hypothesized that diatom exudates may tune microbial communities and employed an integrated multiomics approach using the ubiquitous diatom Asterionellopsis glacialis to reveal how it modulates its naturally associated bacteria. We show that A. glacialis reprograms its transcriptional and metabolic profiles in response to bacteria to secrete a suite of central metabolites and two unusual secondary metabolites, rosmarinic acid and azelaic acid. While central metabolites are utilized by potential bacterial symbionts and opportunists alike, rosmarinic acid promotes attachment of beneficial bacteria to the diatom and simultaneously suppresses the attachment of opportunists. Similarly, azelaic acid enhances growth of beneficial bacteria while simultaneously inhibiting growth of opportunistic ones. We further show that the bacterial response to azelaic acid is numerically rare but globally distributed in the world's oceans and taxonomically restricted to a handful of bacterial genera. Our results demonstrate the innate ability of an important unicellular eukaryotic group to modulate select bacteria in their microbial consortia, similar to higher eukaryotes, using unique secondary metabolites that regulate bacterial growth and behavior inversely across different bacterial populations.


Assuntos
Bactérias/crescimento & desenvolvimento , Diatomáceas/metabolismo , Microbiota/fisiologia , Fitoplâncton/metabolismo , Microbiologia da Água , Animais , Bactérias/genética , Cinamatos/metabolismo , Depsídeos/metabolismo , Diatomáceas/genética , Ácidos Dicarboxílicos/metabolismo , Perfilação da Expressão Gênica , Metabolômica , Metagenoma , Metagenômica , Oceanos e Mares , Fitoplâncton/genética , Metabolismo Secundário/fisiologia , Ácido Rosmarínico
3.
Environ Microbiol ; 22(11): 4761-4778, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32896070

RESUMO

Interactions between phytoplankton and bacteria play major roles in global biogeochemical cycles and oceanic nutrient fluxes. These interactions occur in the microenvironment surrounding phytoplankton cells, known as the phycosphere. Bacteria in the phycosphere use either chemotaxis or attachment to benefit from algal excretions. Both processes are regulated by quorum sensing (QS), a cell-cell signalling mechanism that uses small infochemicals to coordinate bacterial gene expression. However, the role of QS in regulating bacterial attachment in the phycosphere is not clear. Here, we isolated a Sulfitobacter pseudonitzschiae F5 and a Phaeobacter sp. F10 belonging to the marine Roseobacter group and an Alteromonas macleodii F12 belonging to Alteromonadaceae, from the microbial community of the ubiquitous diatom Asterionellopsis glacialis. We show that only the Roseobacter group isolates (diatom symbionts) can attach to diatom transparent exopolymeric particles. Despite all three bacteria possessing genes involved in motility, chemotaxis, and attachment, only S. pseudonitzschiae F5 and Phaeobacter sp. F10 possessed complete QS systems and could synthesize QS signals. Using UHPLC-MS/MS, we identified three QS molecules produced by both bacteria of which only 3-oxo-C16:1 -HSL strongly inhibited bacterial motility and stimulated attachment in the phycosphere. These findings suggest that QS signals enable colonization of the phycosphere by algal symbionts.


Assuntos
Aderência Bacteriana , Diatomáceas/microbiologia , Locomoção , Fitoplâncton/microbiologia , Percepção de Quorum/fisiologia , 4-Butirolactona/análogos & derivados , 4-Butirolactona/metabolismo , Bactérias/classificação , Bactérias/genética , Bactérias/metabolismo , Aderência Bacteriana/genética , Genes Bacterianos , Locomoção/genética , Microbiota , Oceanos e Mares , Percepção de Quorum/genética
4.
Cureus ; 16(6): e62242, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-39006616

RESUMO

Traumatic brain injury (TBI) consists of an external physical force that causes brain function impairment or pathology and globally affects 50 million people each year, with a cost of 400 billion US dollars. Clinical presentation of TBI can occur in many forms, and patients usually require prolonged hospital care and lifelong rehabilitation, which leads to an impact on the quality of life. For this narrative review, no particular method was used to extract data. With the aid of health descriptors and Medical Subject Heading (MeSH) terms, a search was thoroughly conducted in databases such as PubMed and Google Scholar. After the application of exclusion and inclusion criteria, a total of 146 articles were effectively used for this review. Results indicate that rehabilitation after TBI happens through neuroplasticity, which combines neural regeneration and functional reorganization. The role of technology, including artificial intelligence, virtual reality, robotics, computer interface, and neuromodulation, is to impact rehabilitation and life quality improvement significantly. Pharmacological intervention, however, did not result in any benefit when compared to standard care and still needs further research. It is possible to conclude that, given the high and diverse degree of disability associated with TBI, rehabilitation interventions should be precocious and tailored according to the individual's needs in order to achieve the best possible results. An interdisciplinary patient-centered care health team and well-oriented family members should be involved in every stage. Lastly, strategies must be adequate, well-planned, and communicated to patients and caregivers to attain higher functional outcomes.

5.
Cureus ; 16(6): e63489, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-39081430

RESUMO

E-cigarettes (ECs) deliver chemicals, including nicotine. They can cause respiratory distress, addiction, cardiovascular effects, and death. More research is needed, especially regarding their impact on the cardiovascular system (CVS) and during pregnancy. Our article aims to fill this gap by summarizing studies elaborating upon the current impact of ECs and the components thereof on the CVS. Acute respiratory distress outbreaks, nicotine addiction, CVS effects, and deaths have been occasionally reported within this cohort, although these events are not uncommon with neighboring age groups. Randomized control trials implying ECs have some contribution toward quitting smoking have been studied. To regulate EC distribution, the Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC) have created key checkpoints. Additionally, taxation, pricing, age restriction, and media campaigns could be modulated to significantly reduce illicit sales. Education to the users, distributors, and regulators about this product can also play an aiding role in promoting responsible EC use. Another strategy about licensing could be employed, which could incentivize genuine resellers. The effects on CVS and child-bearing by ECs are grim, which calls for strict regulation, awareness, and avoidance by the teetotaler public. They may help individuals stop smoking but not without harming themselves. Strict regulations are necessary to prevent non-judicious use of these devices.

6.
Elife ; 122024 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-38189382

RESUMO

Photosynthetic eukaryotes, such as microalgae and plants, foster fundamentally important relationships with their microbiome based on the reciprocal exchange of chemical currencies. Among these, the dicarboxylate metabolite azelaic acid (Aze) appears to play an important, but heterogeneous, role in modulating these microbiomes, as it is used as a carbon source for some heterotrophs but is toxic to others. However, the ability of Aze to promote or inhibit growth, as well as its uptake and assimilation mechanisms into bacterial cells are mostly unknown. Here, we use transcriptomics, transcriptional factor coexpression networks, uptake experiments, and metabolomics to unravel the uptake, catabolism, and toxicity of Aze on two microalgal-associated bacteria, Phycobacter and Alteromonas, whose growth is promoted or inhibited by Aze, respectively. We identify the first putative Aze transporter in bacteria, a 'C4-TRAP transporter', and show that Aze is assimilated through fatty acid degradation, with further catabolism occurring through the glyoxylate and butanoate metabolism pathways when used as a carbon source. Phycobacter took up Aze at an initial uptake rate of 3.8×10-9 nmol/cell/hr and utilized it as a carbon source in concentrations ranging from 10 µM to 1 mM, suggesting a broad range of acclimation to Aze availability. For growth-impeded bacteria, we infer that Aze inhibits the ribosome and/or protein synthesis and that a suite of efflux pumps is utilized to shuttle Aze outside the cytoplasm. We demonstrate that seawater amended with Aze becomes enriched in bacterial families that can catabolize Aze, which appears to be a different mechanism from that in soil, where modulation by the host plant is required. This study enhances our understanding of carbon cycling in the oceans and how microscale chemical interactions can structure marine microbial populations. In addition, our findings unravel the role of a key chemical currency in the modulation of eukaryote-microbiome interactions across diverse ecosystems.


Assuntos
Ácidos Dicarboxílicos , Ecossistema , Humanos , Transporte Biológico , Carbono
7.
Front Microbiol ; 12: 718297, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34447362

RESUMO

The multiple interactions of phytoplankton and bacterioplankton are central for our understanding of aquatic environments. A prominent example of those is the consistent association of diatoms with Alphaproteobacteria of the order Rhodobacterales. These photoheterotrophic bacteria have traditionally been described as generalists that scavenge dissolved organic matter. Many observations suggest that members of this clade are specialized in colonizing the microenvironment of diatom cells, known as the phycosphere. However, the molecular mechanisms that differentiate Rhodobacterales generalists and phycosphere colonizers are poorly understood. We investigated Rhodobacterales in the North Sea during the 2010-2012 spring blooms using a time series of 38 deeply sequenced metagenomes and 10 metaproteomes collected throughout these events. Rhodobacterales metagenome assembled genomes (MAGs) were recurrently abundant. They exhibited the highest gene enrichment and protein expression of small-molecule transporters, such as monosaccharides, thiamine and polyamine transporters, and anaplerotic pathways, such as ethylmalonyl and propanoyl-CoA metabolic pathways, all suggestive of a generalist lifestyle. Metaproteomes indicated that the species represented by these MAGs were the dominant suppliers of vitamin B12 during the blooms, concomitant with a significant enrichment of genes related to vitamin B12 biosynthesis suggestive of association with diatom phycospheres. A closer examination of putative generalists and colonizers showed that putative generalists had persistently higher relative abundance throughout the blooms and thus produced more than 80% of Rhodobacterales transport proteins, suggesting rapid growth. In contrast, putative phycosphere colonizers exhibited large fluctuation in relative abundance across the different blooms and correlated strongly with particular diatom species that were dominant during the blooms each year. The defining feature of putative phycosphere colonizers is the presence of the tight adherence (tad) gene cluster, which is responsible for the assembly of adhesive pili that presumably enable attachment to diatom hosts. In addition, putative phycosphere colonizers possessed higher prevalence of secondary metabolite biosynthetic gene clusters, particularly homoserine lactones, which can regulate bacterial attachment through quorum sensing. Altogether, these findings suggest that while many members of Rhodobacterales are competitive during diatom blooms, only a subset form close associations with diatoms by colonizing their phycospheres.

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