Scholarly Work - Center for Biofilm Engineering
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Item Struvite Stone Formation by Ureolytic Biofilms(2019) Espinosa-Ortiz, Erika J.; Gerlach, RobinThis chapter describes the role ureolytic biofilms (communities of microbes attached to surfaces) play in struvite stone formation in the urinary tract. The formation of struvite stones (MgNH4PO4·6H2O), commonly known as infection stones, is associated with urinary tract infections, particularly, with ureolytic microorganisms. Establishment of ureolytic biofilms in the urinary tract can result in increased microbial resistance to medical treatment and development of the necessary urine conditions to promote struvite (or other mineral) precipitation possibly leading to stone formation. Ureolytic microorganisms produce urease, an enzyme that breaks down urea (CO(NH2)2) generating ammonium (NH4+) and alkalizing urine, which changes urine chemistry to potentially promote struvite and other mineral precipitation. This chapter describes the series of steps involved in biofilm development and struvite precipitation leading to stone formation. Furthermore, this chapter presents an overview of controlled laboratory experiments and computer simulations currently used in different disciplines to study microbe-fluid-mineral interactions. We conclude that an interdisciplinary approach including the disciplines of engineering, mathematics, chemistry, microbiology and medicine will provide a more comprehensive understanding of the process of stone formation in the urinary tract and will ultimately allow for the development of improved management and prevention strategies for infection stones.Item Biofilms in porous media(2000) Bouwer, Edward J.; Rijnaarts, Huub H. M.; Cunningham, Alfred B.; Gerlach, RobinItem Influence of biofilms on porous media hydrodynamics(2010-08) Gerlach, Robin; Cunningham, Alfred B.Microbial biofilms form in natural and engineered systems and can significantly affect the hydrodynamics in porous media. Microbial biofilms develop through the attachment and growth of microorganisms, which encase themselves in self-produced extracellular polymeric substances (EPS). Microbial biofilms are, in general, more resistant to environmental stresses, such as mechanical stress, temperature, pH, and water potential fluctuations, than planktonic cells. Biofilm growth in porous media influences porosity, permeability, dispersion, diffusion, and mass transport of reactive and nonreactive solutes. Understanding and controlling biofilm formation in porous media will maximize the potential benefit and will minimize the detrimental effects of porous media biofilms. Subsurface remediation, enhanced oil recovery, and carbon sequestration are only a few examples of beneficial porous media biofilm applications.Item Pathways of 2,4,6-trinitrotoluene transformation by aerobic yeasts(2013-08) Ziganshin, Ayrat M.; Gerlach, RobinThe production and use of various highly persistent synthetic compounds lead to environmental pollution. Among such compounds, 2,4,6-trinitrotoluene (TNT) is the one which is commonly used as an explosive. Synthesis and wide use of TNT in ammunition have resulted in the contamination of soil, air, surface water, and groundwater. TNT and its nitro group reduction products are highly toxic, potentially mutagenic and persistent contaminants which can persist in the environment for a long time (Spain et al. 2000; Stenuit et al. 2005; Smets et al. 2007; Singh et al. 2012). The U.S. Environmental Protection Agency has classified TNT as one of the most dangerous pollutants in the biosphere. Hence, remediation of TNT-contaminated sites is urgently warranted at places of its production and use (Keith and Telliard 1979; Fiorella and Spain 1997).Human exposure to TNT or its nitro group reduction metabolites can lead to the development of diseases, such as aplastic anemia, cataracts, impaired liver function and the formation of tumors in the urinary tract (Hathaway 1985; Yinon 1990; Leung et al. 1995). Hence, it is inevitable to work out strategies targeting the degradation of TNT.Decontamination of sites contaminated with explosives, especially with TNT, is possible with application of various physical, chemical, and biological methods. The main advantages of bioremediation are environmental friendliness and involvement of low cost (Rodgers and Bunce 2001).Item Struvite stone formation by ureolytic biofilm infections(2016) Schultz, Logan N.; Connolly, James M.; Lauchnor, Ellen G.; Hobbs, Trace; Gerlach, RobinThis chapter describes how urinary tract infections can lead to stone formation. The most frequent type of infection stone is struvite (MgNH4PO4 · 6H2O), although it is common that struvite stones and infections are associated with other stone types, often forming large staghorn calculi. A complete understanding of struvite stone formation requires knowledge of the pathogen biology, including metabolic activity and motility, as well as a basic understanding of how minerals form.The pathogens responsible for struvite stones are those that break down urea into ammonium (NH4 +) and inorganic carbon. This reaction, known as ureolysis, increases the pH of urine and the concentration of NH4 +, thus increasing the saturation index of struvite. If supersaturation is reached, i.e. the ion activity product (IAP) is greater than the ion activity product at equilibrium (Ksp), struvite stone formation is possible.An important consideration with urinary tract infections is that pathogens often form attached communities, known as biofilms, which help them to survive physical and chemical stresses. Not only are biofilm-related infections more difficult to treat, but they can facilitate stone formation by creating gradients in chemical concentrations near surfaces. Modern laboratory bioreactors and computer models, described in this chapter, are improving our understanding of how and why infection stones such as struvite form. Current treatment options for infection stones can be painful or ineffective. As more is learned about the complex microbe-fluid-mineral interactions, less-invasive treatments and more-effective prevention strategies will be developed.Book title: The Role of Bacteria in Urology Lange D, Chew B, (Eds.): Springer, 2015; pp. 41–49.