@conference_item {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/98365,
    title ="Calorimetric determination of microbial activity in low-\u200benergy environments",
    author = "Amend, Jan and Feyhl-Buska, Jayme",
    
    
    
    pages = "GEOC-0044",
    month = "April",
    year = "2019",
    
    
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20190830-092706647",
    note = "© 2019 American Chemical Society.",
    revision_no = "9",
    abstract = "Calorimetric measurements of heat flow and total heat prodn. can inform on the energetics of microbial activity.  Nanocalorimetry permits such investigations in environments (natural or lab.) where energy supplies are extremely limited and/or very few cells are metabolically active.  We will present nanocalorimetry data obtained during incubations of unamended formation fluids from the oceanic crust (∼300 m deep at the Juan de Fuca Ridge flank) and the continental subsurface (∼1500 m deep at the Sanford Underground Research Facility in South Dakota).  Enthalpic responses by the resident microbial communities to addn. of org. carbon, inorg. electron donors, and nutrients will also be discussed.  We further used nanocalorimetry on lab. expts. with model organisms to det. the energetics assocd. with carbon, electron donor, and nutrient limitations.  For example, with a sulfate reducing bacterium, we quantified the significant cost during the metabolic transition from ammonium assimilation to N_2 fixation.  In another set of expts., with an evolving population of E. coli mutants that express the GASP (growth advantage in stationary phase) phenotype, we recorded distinct heat events assocd. with the emergence of nascent mutant populations.",
}
@conference_item {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/42181,
    title ="High resolution profiling of sulfur and oxygen speciation in microbial mats: Implications for coupling of hydrogen peroxide with sulfur species",
    author = "Druschel, Greg K. and Kafantaris, Fotios",
    
    
    
    pages = "GEOC-38",
    month = "April",
    year = "2013",
    
    
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20131101-092236803",
    note = "© 2013 American Chemical Society.",
    revision_no = "13",
    abstract = "Hydrogen sulfide is produced in microbial mats by sulfate reducing bacteria, and diffuses towards the surface\nuntil it is consumed. Cyanobacteria in these mats are able to produce oxygen photochem., and when\nsubjected to high UV light intensity, can also produce hydrogen peroxide. Microelectrodes have proven to have\nsufficient resoln. to resolve the sulfur and oxygen chem. in these mats, demonstrating the links between\nthese populations of bacteria in modern mats. In sulfur-dominated cyanobacterial mats in several settings, we\nhave obsd. both high hydrogen sulfide fluxes and the periodic prodn. of significant amts. of hydrogen peroxide\nat times of high UV stress using voltammetric Au-amalgam microelectrodes. We review the use of voltammetric\nand amperometric microelectrodes in approaching this chem., and how the relative rates of sulfur species\noxidn. with oxygen or peroxide may play a significant role in shaping the chem., isotopic, and biol. compn. of\nthese systems.",
}