A5040581317- Microbial Community Ecology and Physiology
- Marine and coastal ecosystems
- Marine Biology and Ecology Research
- Atmospheric chemistry and aerosols
- Alcoholism and Thiamine Deficiency
- Folate and B Vitamins Research
- Protist diversity and phylogeny
- Metabolism and Genetic Disorders
- Atmospheric aerosols and clouds
- Climate change and permafrost
- Aquatic Ecosystems and Phytoplankton Dynamics
- Cryospheric studies and observations
- Wastewater Treatment and Nitrogen Removal
- Ocean Acidification Effects and Responses
- Icing and De-icing Technologies
- Isotope Analysis in Ecology
- Marine and coastal plant biology
- Microbial Metabolic Engineering and Bioproduction
- Water Quality and Pollution Assessment
- Genomics and Phylogenetic Studies
- Amino Acid Enzymes and Metabolism
- Arctic and Antarctic ice dynamics
- Diatoms and Algae Research
- Water Quality Monitoring Technologies
- Water Quality Monitoring and Analysis
North Carolina State University
2018-2025
North Central State College
2018-2024
University of Copenhagen
2016-2018
University of California, San Diego
2012-2016
Scripps Institution of Oceanography
2011-2016
University of California, Santa Cruz
2008-2014
Abstract Many diatoms that inhabit low-nutrient waters of the open ocean live in close association with cyanobacteria. Some these associations are believed to be mutualistic, where N2-fixing cyanobacterial symbionts provide N for diatoms. Rates N2 fixation by symbiotic cyanobacteria and transfer their diatom partners were measured using a high-resolution nanometer scale secondary ion mass spectrometry approach natural populations. Cell-specific rates (1.15–71.5 fmol per cell h−1) similar...
Summary The abundances of six N 2 ‐fixing cyanobacterial phylotypes were profiled at 22 stations across the tropical Atlantic Ocean during June 2006, and used to model contribution diazotrophs fixation. Diazotroph measured by targeting nifH gene Trichodesmium , unicellular groups A, B, C (UCYN‐A, UCYN‐B UCYN‐C), diatom‐cyanobiont symbioses Hemiaulus–Richelia Rhizosolenia–Richelia Chaetoceros–Calothrix . West east gradients in temperature, salinity nutrients [NO 3 ‐ + NO PO 4 3− Si(OH) ]...
We confirmed multiple picoeukaryotic algae, Ostreococcus, Micromonas, and Pelagomonas spp., as thiamine (vitamin B1) auxotrophs in laboratory experiments with axenic cultures. Examined strains have half saturation growth constants (Ks) for B1 between 1.26 6.22 pmol L−1, which is higher than reported seawater concentrations. Minimum cell quotas Ostreococcus Micromonas spp. are high (2.20 × 10−8–4.46 10−8 cell−1) relative to other auxotrophic phytoplankton, potentially making them rich prey...
Abstract Vitamin B1 (thiamin, B1) is an essential micronutrient for cells, yet intriguingly in aquatic systems most bacterioplankton are unable to synthesize it de novo (auxotrophy), requiring exogenous source. Cycling of this valuable metabolite has not been fully investigated and vitamers (B1-related compounds) have only begun be measured incorporated into the cycle. Here, we identify potential key producers consumers gain new insights dynamics cycling through measurements (HMP:...
Putative heterotrophic bacteria carrying out N2-fixation, so-called non-cyanobacterial diazotrophs (NCDs), are widely distributed in marine waters, but details of how the O2-inhibited N2-fixation process is promoted oxic water column remains largely ambiguous. In this study we carried two experiments with from a eutrophic temperate fjord to examine whether low-oxygen microenvironments within particulate organic matter could be loci suitable for by these bacteria. First, enriched natural...
Significance Virtually all organisms require vitamin B1, including bacterioplankton that impact nutrient cycling and productivity in aquatic systems Earth’s climate. Here, we show B1 auxotrophy, the need for exogenous or precursors survival, is widespread among wild bacterioplankton. Genetic analyses of revealed most are auxotrophs abundance several B1-related genotypes changes temporally at an estuarine monitoring station, suggesting B1/precursor availability influences succession....
Several cosmopolitan marine picoeukaryotic phytoplankton are B1 auxotrophs requiring exogenous vitamin or precursor to survive. From genomic evidence, representatives of (Ostreococcus and Micromonas spp.) were predicted use known thiazole pyrimidine precursors meet their demands, however, recent culture-based experiments could not confirm this assumption. We hypothesized these strains grow on alone, but required a thiazole-related other the well-known extensively tested...
Abstract The sources and concentrations of ice‐nucleating particles (INPs) over India are not well known. Here, INP in rainwater from Northern a dust sample the Thar Desert characterized. Rainwater ranged between 10 4 3 × 7 L −1 water, spanning temperatures −4 −28 °C. During monsoon season, were low approached those remote marine air mass. winter INPs active to −10 °C occasionally observed. An increase activity sometimes occurred after initial onset rain. freezing temperature samples at...
Picophytoplankton (PicoP) are increasingly recognized as significant contributors to primary productivity and phytoplankton biomass in coastal estuarine systems. Remarkably though, PicoP composition is unknown or not well-resolved several large estuaries including the semi-lagoonal Neuse River Estuary (NRE), a tributary of second largest estuary-system lower USA, Pamlico-Albemarle Sound. The NRE impacted by extreme weather events, recent increases precipitation flooding associated with...
Biological dinitrogen fixation (BNF) represents a major input of reduced nitrogen (N) to the oceans. Accurate direct measurements BNF rates are crucial for reliably determining biogeochemical significance diazotrophy at local and global scales. Traditionally, borosilicate glass fiber filters (GF/F, Whatman) with nominal pore size 0.7 µm used collect suspended particles by filtration after incubations added 15N2 tracer. We carried out experiments in Baltic Sea, Danish coastal waters, Pacific...
Oceanic habitats may select for different organisms, thereby tuning genomic capabilities to local environmental conditions. To understand the relationship between microbial assemblage composition, functional capability, and habitat, a random genome shotgun sequencing (metagenomic) survey was conducted with surface‐water assemblages (0.2–5‐µm size fraction) collected at seven locations along meridional transect from northern edge of South Pacific subtropical gyre southern North (16°S–13.5°N)....
Synechococcus is an abundant marine cyanobacterial genus composed of different populations that vary physiologically. narB gene sequences (encoding for nitrate reductase in cyanobacteria) obtained previously from isolates and the environment (e.g. North Pacific Gyre Station ALOHA, Hawaii or Monterey Bay, California) were used to develop quantitative PCR (qPCR) assays. These qPCR assays quantify specific phylogenetic clades across California Current System (CCS), a region dynamic zones...
B-vitamins are essential micronutrients for marine plankton. Additionally, we now know many plankton cannot synthesize de novo (from scratch) and thus reliant on external supplies. Details of B-vitamin exchange, whether ‘active’ or ‘passive’ (i.e. through cell secretion mortality), lacking as a result struggle to predict microbial physiology, community composition biogeochemistry. We argue that significant advances in understanding the impact exchange cycling structure biogeochemistry can be...
Almost all cells require thiamin, vitamin B1 (B1), which is synthesized via the coupling of thiazole and pyrimidine precursors. Here we demonstrate that 5-(2-hydroxyethyl)-4-methyl-1,3-thiazole-2-carboxylic acid (cHET) a useful in vivo precursor for representatives ubiquitous marine picoeukaryotic phytoplankton Escherichia coli - drawing attention to cHET as valuable exogenous micronutrient microorganisms with ecological, industrial, biomedical value. Comparative utilization experiments...
Abstract Marine dissolved organic matter (DOM) is a massive elemental pool on Earth and thought to consist of chemically complex mixture molecules. Part marine DOM fluorescent (FDOM) includes humic‐like compounds. The chemical composition of, biochemical pathways that yield, autochthonous FDOM in the ocean largely unknown. Inspired by medical research detailing formation colored dityrosine via peroxidase mediated reactions, we used fluorometry spectroscopy found exhibits fluorescence similar...
Microbial communities occupy diverse niches in nature, and community members routinely exchange a variety of nutrients among themselves. While large-scale metagenomic metabolomic studies shed some light on these exchanges, the contribution individual species molecular details specific interactions are difficult to track. In this study, we follow vitamin B1 (thiamin) its intermediates between microbes within synthetic cocultures Escherichia coli Vibrio anguillarum. Thiamin contains two...
Cyanobacteria are important primary producers, sources of secondary metabolites, and sentinels environmental change in aquatic ecosystems – including large estuaries. Here, we newly investigated cyanobacterial diversity within the Albemarle Pamlico Sound System (APES) using (16S rRNA) gene amplicon sequencing analyses. Substantial lineages lacking current isolates were recovered (46 genera, 17 potentially cyanotoxic), with oligohaline waters its tributaries being notable regional hotspot for...