Photosynthetic picoeukaryotes are significant contributors to marine primary productivity. Associations between marine bacterioplankton and picoeukaryotes frequently occur and can have large biogeochemical impacts. We used flow cytometry to sort cells from seawater to identify non-eukaryotic phylotypes that are associated with photosynthetic picoeukaryotes. Samples were collected at the Santa C...

The conservation of the phosphoanhydride-energy of inorganic pyrophosphate (PP) in microbial metabolism requires a stringent metabolic control of the intracellular pyrophosphatases (PPases, EC 3.6.1.1). In this article, the rate of intracellular PP-liberation during biosynthesis of cellular constituents is calculated from the specific growth rate and the macromolecular composition of the respec...

Photosynthetic acclimation under elevated carbon dioxide (CO(2)) and/or ozone (O(3)) has been the topic of discussion in many papers recently. We examined whether or not aspen plants grown under elevated CO(2) and/or O(3) will acclimate after 11 years of exposure at the Aspen Face site in Rhinelander, WI, USA. We studied diurnal patterns of instantaneous photosynthetic measurements as well as A...

The natural light environment is important to many prokaryotes. Most obviously, phototrophic prokaryotes need to acclimate their photosynthetic apparatus to the prevailing light conditions, and such acclimation is frequently complemented by motility to enable cells to relocate in search of more favorable illumination conditions. Non-phototrophic prokaryotes may also seek to avoid light at damag...

Strong exciton-photon coupling is the result of a reversible exchange of energy between an excited state and a confined optical field. This results in the formation of polariton states that have energies different from the exciton and photon. We demonstrate strong exciton-photon coupling between light-harvesting complexes and a confined optical mode within a metallic optical microcavity. The en...

The earliest primary photochemical reaction of green plant photosynthesis has, thus far, remained unexplored as reaction center chlorophyll a (Chl a) complexes have not yet been isolated [l] . In contrast, primary photochemical steps have been successfully studied, with picosecond (ps) absorption spectroscopy [2,3] in isolated bacteriochlorophyll (B Chl)-reaction center complexes from photosynt...

Chlorosomes are large light-harvesting complexes found in three phyla of anoxygenic photosynthetic bacteria. Chlorosomes are primarily composed of self-assembling pigment aggregates. In addition to the main pigment, bacteriochlorophyll c, d, or e, chlorosomes also contain variable amounts of carotenoids. Here, we use X-ray scattering and electron cryomicroscopy, complemented with absorption spe...

A strain of the aerobic anoxygenic photosynthetic bacteria was isolated from a deep-ocean hydrothermal vent plume environment. The in vivo absorption spectra of cells indicate the presence of bacteriochlorophyll a incorporated into light-harvesting complex I and a reaction center. The general morphological and physiological characteristics of this new isolate are described.

Extracts of representative bacterial strains from the various families of photosynthetic prokaryotes are demonstrated to possess significant levels of sulfite reductase [EC 1.8.99.1; hydrogen-sulfide: (acceptor)oxidoreductase] activity with reduced methyl viologen as electron donor, but not NADPH(2). The enzyme is localized primarily in the soluble fraction of the extracts, in contrast to adeny...

Photosynthetic tissues are organized functionally into aggregates of light harvesting pigments (mainly chlorophylls, carotenoids, and phycobilins) associated with photochemical reaction centers (1, 2). The pigments absorb light and deliver the energy to the reaction centers, where an oxido-reductive photochemistry ensues. The primary photoproducts, oxidizing and reducing entities, serve as star...