Scholarly Work - Center for Biofilm Engineering
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Item Transition of biogenic coal-to-methane conversion from the laboratory to the field: a review of important parameters and studies(2018-01) Davis, Katherine J.; Gerlach, RobinCoalbed methane (CBM) is an important unconventional natural gas resource in the U.S. and around the world. Many of the CBM containing coal formations are home to microbial communities producing the gas by converting coal to methane. Biogenically produced CBM provides an opportunity for developing technologies to enhance the microbial processes and increase the recoverable gas. To transfer strategies for biogenic CBM enhancement from small-scale laboratory studies to large-scale commercial applications in subsurface coal beds, there are several factors that should be considered to facilitate this transfer. Coal rank, chemistry and structure, formation water chemistry, as well as microbial communities can vary widely among coal formations, and matching these components in laboratory studies to each other and the coal bed of interest should be considered. More work is required to understand the effects of gas sorption, pressure, and water movement through coal formations on biogenic gas production. Additionally, methods for applying methane enhancement strategies in situ must be further investigated to develop commercial applications of enhanced microbial coalbed methane production.Item Evaluation of Biofilm Induced Urinary Infection Stone Formation in a Novel Laboratory Model System(2018-01) Hobbs, Trace; Schultz, Logan N.; Lauchnor, Ellen G.; Gerlach, Robin; Lange, D.Purpose Infection stones, which comprise approximately 15% of all urinary tract stones, are induced by infection with urease-positive pathogens. The bacteria in the stone matrix present significant treatment impediments compared to metabolic kidney stones. While much is known about how urinary composition regulates metabolic stone formation, there is a general lack of knowledge of which urinary factors regulate the rate of infection stone formation. Unfortunately more in-depth research into infection stones is limited by the lack of suitable models for real-time study of bacterial biofilm formation and stone formation under varying conditions. Materials and Methods We developed an in vitro model to study infection stone formation. The model closely represents the processes that occur in vivo, including the observed migration of ureolytic bacteria (our culture of Proteus mirabilis) from the bladder to the kidneys, followed by biofilm and stone formation in the kidney. We used scanning electron and confocal laser microscopy, x-ray diffraction, biological counts and dissolved chemical analyses to evaluate the model system. Results Crystals that formed in the system resembled clinically removed struvite stones in structure and composition. Results showed that the degree of ureolysis required to significantly change urine pH was minimal, bacterial communities inhabited the ureter, and upstream colonization and struvite formation required lag time. Conclusions These results have implications for the detection and treatment of struvite stones. Currently this model is being used to study specific urinary factors that regulate struvite formation to identify treatment options, which combined with antibiotics would improve treatment of these stones and decrease recurrence.Item Dissimilatory iron-reducing bacteria can influence the reduction of carbon tetrachloride by iron metal(2000-06) Gerlach, Robin; Cunningham, Alfred B.; Caccavo, FrankLittle is known about the long-term performance of zerovalent iron (Fe0) subsurface barriers. Groundwater exposure includes corrosion processes that can passivate the Fe0 surface and decrease barrier reaction rates. We present evidence that dissimilatory iron-reducing bacteria (DIRB) can stimulate the rate of carbon tetrachloride (CT) transformation in the presence of corroded iron. The DIRB, Shewanella alga BrY, adhered to the corroded Fe surfaces that showed little or no capacity to transform CT. The addition of BrY to these systems with decreased CT transformation rates resulted in increased ferrous iron concentrations and increased CT transformation to chloroform (CF). The results suggest that DIRB can have an influence on the long-term performance of Fe0 barriers.Item Bacterial transport issues related to subsurface biobarriers(1999) Sharp, Robert R.; Gerlach, Robin; Cunningham, Alfred B.Item Chromium elimination with microbially reduced iron: redox-reactive biobarriers(1999) Gerlach, Robin; Cunningham, Alfred B.; Caccavo, FrankItem Type and amount of organic amendments affect enhanced biogenic methane production from coal and microbial community structure(2018-01) Davis, Katherine J.; Shipeng, Lu; Barnhart, Elliott P.; Parker, Albert E.; Fields, Matthew W.; Gerlach, RobinSlow rates of coal-to-methane conversion limit biogenic methane production from coalbeds. This study demonstrates that rates of coal-to-methane conversion can be increased by the addition of small amounts of organic amendments. Algae, cyanobacteria, yeast cells, and granulated yeast extract were tested at two concentrations (0.1 and 0.5 g/L), and similar increases in total methane produced and methane production rates were observed for all amendments at a given concentration. In 0.1 g/L amended systems, the amount of carbon converted to methane minus the amount produced in coal only systems exceeded the amount of carbon added in the form of amendment, suggesting enhanced coal-to-methane conversion through amendment addition. The amount of methane produced in the 0.5 g/L amended systems did not exceed the amount of carbon added. While the archaeal communities did not vary significantly, the bacterial populations appeared to be strongly influenced by the presence of coal when 0.1 g/L of amendment was added; at an amendment concentration of 0.5 g/L the bacterial community composition appeared to be affected most strongly by the amendment type. Overall, the results suggest that small amounts of amendment are not only sufficient but possibly advantageous if faster in situ coal-to-methane production is to be promoted.Item Biogeochemical elimination of chromium (VI) contaminated water(2002-01) Nyman, Jennifer L.; Caccavo, Frank; Cunningham, Alfred B.; Gerlach, RobinFerrous iron [Fe(II)] reductively transforms heavy metals in contaminated groundwater, and the bacterial reduction of indigenous ferric iron [Fe(II)] has been proposed as a means of establishing redox reactive barriers in the subsurface. The reduction of Fe(III) to Fe(II) can be accomplished by stimulation of microbially produced Fe(II) can chemically react with contaminants such as Cr(VI) to form insoluble Cr(III) precipitates. The DMRB Shewanella algae BrY reduced highly soluble Cr(VI) to insoluble Cr(III). Once the chemical Cr(VI) reduction capacity of the Fe(II)/Fe(III) couple in the experimental systems was exhausted, the addition of S. algae BrY allowed for the repeated reduction of Fe(III) to Fe(II), which again reduced Cr(VI) to Cr(III). The research presented herein indicates that a biological process using DMRB allows the establishment of biogeochemical cycle that facilitates chromium production. Such a system could provide a means for establishing and maintaining remedial redox reactive zones on Fe(III)- bearing subsurface environments.Item Anomalous fluid transport in porous media induced by biofilm growth(2004-11) Seymour, Joseph D.; Gage, Justin P.; Codd, Sarah L.; Gerlach, RobinMagnetic resonance measurements of the transition from normal to anomalous hydrodynamic dispersion in porous media due to biological activity are presented. Fractional advection-diffusion equations are shown to provide models for the measured impact of biofilm growth on porous media transport dynamics.Item Biofilms in porous media(2000) Bouwer, Edward J.; Rijnaarts, Huub H. M.; Cunningham, Alfred B.; Gerlach, RobinItem Use of reversed-phase high-performance liquid chromatography-diode array detection for complete separation of 2,4,6-trinitrotoluene metabolites and EPA Method 8330 explosives: Influence of temperature and an ion-pair reagent(2004-01) Borch, Thomas; Gerlach, RobinExplosives such as 2,4,6-trinitrotoluene (TNT), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) are widely distributed environmental contaminants. Complete chromatographic separation is necessary in order to accurately determine and quantify explosives and their degradation products in environmental samples and in (bio)transformation studies. The present study describes a RP-HPLC method with diode array detection using a LC-8 guard column, a Supelcosil LC-8 chromatographic column, and a gradient elution system. This gradient method is capable of baseline separating the most commonly observed explosives and TNT transformation metabolites including 2,4,6-triaminotoluene (TAT) in a single run. The TNT metabolites separated were 2-hydroxylamino-4,6-dinitrotoluene, 4-hydroxylamino-2,6-dinitrotoluene, 2,4-dihydroxylamino-6-nitrotoluene, 4,4',6,6'-tetranitro-2,2'-azoxytoluene, 2,2',6,6'-tetranitro-4,4'-azoxytoluene, 4,4',6,6'-tetranitro-2,2'-azotoluene, 2,2',6,6'-tetranitro-4,4'-azotoluene, 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2,6-diamino-4-nitrotoluene, 2,4-diamino-6-nitrotoluene, and TAT. The same gradient method at a different column temperature can also be used to baseline separate the explosives targeted in the Environmental Protection Agency (EPA) Method 8330 with approximately 22% reduction in total run time and 48% decrease in solvent consumption compared to previously published methods. Good separation was also obtained when all TNT metabolites and EPA Method 8330 compounds (a total of 23 compounds) were analyzed together; only 2,6-DANT and HMX co-eluted in this case. The influence of temperature (35B55 C) and the use of an ion-pair reagent on the chromatographic resolution and retention were investigated. Temperature was identified as the key parameter for optimal baseline separation. Increased temperature resulted in shorter retention times and better peak resolution especially for the aminoaromatics investigated. The use of an ion-pair reagent (octanesulfonic acid) generally resulted in longer retention times for compounds containing amine functional groups, more baseline noise, and decreased peak resolution.