Publications by authors named "D J Repeta"

In seawater, most dissolved copper (Cu) is complexed by organic ligands, many of which are thought to be produced by phytoplankton. Although very little is known about the composition and structure of these ligands, they play an important role in determining the reactivity and bioavailability of Cu. In this study, , a marine diatom known to produce Cu ligands (CuLs), was grown in laboratory pure culture, and the CuLs were recovered from the growth media.

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Article Synopsis
  • Primary production in the sunlit ocean relies on nutrients like nitrate, phosphate, and iron, which are essential for phytoplankton to convert CO2 into biomass.
  • Microbial metabolism in the upper mesopelagic 'twilight zone' (200-500 m) is believed to be constrained by the availability of organic carbon.
  • The study reveals high concentrations of siderophores, indicating iron deficiency in both the surface and twilight zone of the eastern Pacific Ocean, suggesting that low iron availability may limit microbial metabolism across larger areas of the ocean, impacting carbon storage.
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The use of ultrafiltration to isolate high molecular weight dissolved organic matter (HMWDOM) from seawater is a fundamental tool in the environmental organic chemist's toolbox. Yet, important characteristics of HMWDOM relevant to its origin and cycling, such as its molecular weight distribution, remain poorly defined. We used diffusion-ordered NMR spectroscopy coupled with mixed-mode chromatography to separate and characterize two major components of marine HMWDOM: acylpolysaccharides (APS) and high molecular weight humic substances (HS).

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The terrestrial serpentinite-hosted ecosystem known as "The Cedars" is home to a diverse microbial community persisting under highly alkaline (pH ~ 12) and reducing (Eh < -550 mV) conditions. This extreme environment presents particular difficulties for microbial life, and efforts to isolate microorganisms from The Cedars over the past decade have remained challenging. Herein, we report the initial physiological assessment and/or full genomic characterization of three isolates: sp.

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We have isolated a chlorophyll--containing cyanobacterium from the intertidal field site at Moss Beach, on the coast of Central California, USA, where Manning and Strain (1943) originally discovered this far-red chlorophyll. Here, we present the cyanobacterium's environmental description, culturing procedure, pigment composition, ultrastructure, and full genome sequence. Among cultures of far-red cyanobacteria obtained from red algae from the same site, this strain was an epiphyte on a brown macroalgae.

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