Molyneaux Stephen J.

No Thumbnail Available
Last Name
Molyneaux
First Name
Stephen J.
ORCID

Filters

2002 - 2006 4
3 1
4
Reset filters

Settings

Search Results

Now showing 1 - 4 of 4
  • Preprint
    Autonomous Microbial Sampler (AMS), a device for the uncontaminated collection of multiple microbial samples from submarine hydrothermal vents and other aquatic environments
    ( 2006-01-11) Taylor, Craig D. ; Doherty, Kenneth W. ; Molyneaux, Stephen J. ; Morrison, Archie T. ; Billings, John D. ; Engstrom, Ivory B. ; Pfitsch, Don W. ; Honjo, Susumu
    An Autonomous Microbial Sampler (AMS) is described that will obtain uncontaminated and exogenous DNA-free microbial samples from most marine, fresh water and hydrothermal ecosystems. Sampling with the AMS may be conducted using manned submersibles, Remotely Operated Vehicles (ROVs), Autonomous Underwater Vehicles (AUVs), or when tethered to a hydrowire during hydrocast operations on research vessels. The modular device consists of a titanium nozzle for sampling in potentially hot environments (>350°C) and fluid-handling components for the collection of six independent filtered or unfiltered samples. An onboard microcomputer permits sampling to be controlled by the investigator, by external devices (e.g., AUV computer), or by internal programming. Temperature, volume pumped and other parameters are recorded during sampling. Complete protection of samples from microbial contamination was observed in tests simulating deployment of the AMS in coastal seawater, where the sampling nozzle was exposed to seawater containing 1x106 cells ml-1 of a red pigmented tracer organism, Serratia marinorubra. Field testing of the AMS at a hydrothermal vent field was successfully undertaken in 2000. Results of DNA destruction studies have revealed that exposure of samples of the Eukaryote Euglena and the bacterium S. marinorubra to 0.5 N sulfuric acid at 23°C for 1 hour was sufficient to remove Polymerase Chain Reaction (PCR) amplifiable DNA. Studies assessing the suitability of hydrogen peroxide as a sterilizing and DNA-destroying agent showed that 20 or 30% hydrogen peroxide sterilized samples of Serratia in 1 hr and destroyed the DNA of Serratia, in 3 hrs, but not 1 or 2 hrs. DNA AWAY™ killed Serratia and destroyed the DNA of both Serratia and the vent microbe (GB-D) of the genus Pyrococcus in 1 hour.
  • Article
    Sulfide ameliorates metal toxicity for deep-sea hydrothermal vent archaea
    (American Society for Microbiology, 2004-04) Edgcomb, Virginia P. ; Molyneaux, Stephen J. ; Saito, Mak A. ; Lloyd, Karen G. ; Boer, Simone ; Wirsen, Carl O. ; Atkins, Michael S. ; Teske, Andreas
    The chemical stress factors for microbial life at deep-sea hydrothermal vents include high concentrations of heavy metals and sulfide. Three hyperthermophilic vent archaea, the sulfur-reducing heterotrophs Thermococcus fumicolans and Pyrococcus strain GB-D and the chemolithoautotrophic methanogen Methanocaldococcus jannaschii, were tested for survival tolerance to heavy metals (Zn, Co, and Cu) and sulfide. The sulfide addition consistently ameliorated the high toxicity of free metal cations by the formation of dissolved metal-sulfide complexes as well as solid precipitates. Thus, chemical speciation of heavy metals with sulfide allows hydrothermal vent archaea to tolerate otherwise toxic metal concentrations in their natural environment.
  • Article
    Effects of dissolved sulfide, pH, and temperature on growth and survival of marine hyperthermophilic archaea
    (American Society for Microbiology, 2005-10) Lloyd, Karen G. ; Edgcomb, Virginia P. ; Molyneaux, Stephen J. ; Boer, Simone ; Wirsen, Carl O. ; Atkins, Michael S. ; Teske, Andreas
    The ability of metabolically diverse hyperthermophilic archaea to withstand high temperatures, low pHs, high sulfide concentrations, and the absence of carbon and energy sources was investigated. Close relatives of our study organisms, Methanocaldococcus jannaschii, Archaeoglobus profundus, Thermococcus fumicolans, and Pyrococcus sp. strain GB-D, are commonly found in hydrothermal vent chimney walls and hot sediments and possibly deeper in the subsurface, where highly dynamic hydrothermal flow patterns and steep chemical and temperature gradients provide an ever-changing mosaic of microhabitats. These organisms (with the possible exception of Pyrococcus strain GB-D) tolerated greater extremes of low pH, high sulfide concentration, and high temperature when actively growing and metabolizing than when starved of carbon sources and electron donors/acceptors. Therefore these organisms must be actively metabolizing in the hydrothermal vent chimneys, sediments, and subsurface in order to withstand at least 24 h of exposure to extremes of pH, sulfide, and temperature that occur in these environments.
  • Article
    Characterization of an autotrophic sulfide-oxidizing marine Arcobacter sp. that produces filamentous sulfur
    (American Society for Microbiology, 2002-01) Wirsen, Carl O. ; Sievert, Stefan M. ; Cavanaugh, Colleen M. ; Molyneaux, Stephen J. ; Ahmad, Azeem ; Taylor, L. T. ; DeLong, Edward F. ; Taylor, Craig D.
    A coastal marine sulfide-oxidizing autotrophic bacterium produces hydrophilic filamentous sulfur as a novel metabolic end product. Phylogenetic analysis placed the organism in the genus Arcobacter in the epsilon subdivision of the Proteobacteria. This motile vibrioid organism can be considered difficult to grow, preferring to grow under microaerophilic conditions in flowing systems in which a sulfide-oxygen gradient has been established. Purified cell cultures were maintained by using this approach. Essentially all 4',6-diamidino-2-phenylindole dihydrochloride-stained cells in a flowing reactor system hybridized with Arcobacter-specific probes as well as with a probe specific for the sequence obtained from reactor-grown cells. The proposed provisional name for the coastal isolate is "Candidatus Arcobacter sulfidicus." For cells cultured in a flowing reactor system, the sulfide optimum was higher than and the CO2 fixation activity was as high as or higher than those reported for other sulfur oxidizers, such as Thiomicrospira spp. Cells associated with filamentous sulfur material demonstrated nitrogen fixation capability. No ribulose 1,5-bisphosphate carboxylase/oxygenase could be detected on the basis of radioisotopic activity or by Western blotting techniques, suggesting an alternative pathway of CO2 fixation. The process of microbial filamentous sulfur formation has been documented in a number of marine environments where both sulfide and oxygen are available. Filamentous sulfur formation by "Candidatus Arcobacter sulfidicus" or similar strains may be an ecologically important process, contributing significantly to primary production in such environments.