Pedro J. J. Alvarez

Bio: Pedro J. J. Alvarez is an academic researcher from Rice University. The author has contributed to research in topics: Bioremediation & Medicine. The author has an hindex of 89, co-authored 378 publications receiving 34837 citations. Previous affiliations of Pedro J. J. Alvarez include University of Minnesota & University of Michigan.

Implications of the Presence of Ethanol on Intrinsic Bioremediation of BTX Plumes in Brazil

Abstract: Intrinsic bioremediation, the use of indigenous microorganisms to degrade hazardous substances within aquifiers without engineered stimulation, shows great promise as a cost-effective approach to hydrocarbon plume management. This technique requires thorough site characterization and monitoring to verify that the natural attenuation processes continue to provide adequate risk protection. Significant progress has been made towards understanding the hydrogeochemical and microbiological factors that influence the feasibility of intrinsic bioremediation of fuel-contaminated aquifers in North America and Europe. Nevertheless, this experience should be extrapolated with care to contaminated sites in Brazil, where gasoline contains about 22% of ethanol. Preliminary laboratory studies show that ethanol can enhance the solubilization of BTX in water, and it might exert diauxic effects during BTX biodegradation. A better understanding of the biochemical, physical, and ecological effects of ethanol is needed to develop a rational basis for the selection, mathematical modeling, and monitoring of appropriate intrinsic bioremediation systems in Brazil. 29 refs., 3 figs.

Phthalate Esters Released from Plastics Promote Biofilm Formation and Chlorine Resistance.

Abstract: Phthalate esters (PAEs) are commonly released from plastic pipes in some water distribution systems. Here, we show that exposure to a low concentration (1-10 μg/L) of three PAEs (dimethyl phthalate (DMP), di-n-hexyl phthalate (DnHP), and di-(2-ethylhexyl) phthalate (DEHP)) promotes Pseudomonas biofilm formation and resistance to free chlorine. At PAE concentrations ranging from 1 to 5 μg/L, genes coding for quorum sensing, extracellular polymeric substances excretion, and oxidative stress resistance were upregulated by 2.7- to 16.8-fold, 2.1- to 18.9-fold, and 1.6- to 9.9-fold, respectively. Accordingly, more biofilm matrix was produced and the polysaccharide and eDNA contents increased by 30.3-82.3 and 10.3-39.3%, respectively, relative to the unexposed controls. Confocal laser scanning microscopy showed that PAE exposure stimulated biofilm densification (volumetric fraction increased from 27.1 to 38.0-50.6%), which would hinder disinfectant diffusion. Biofilm densification was verified by atomic force microscopy, which measured an increase of elastic modulus by 2.0- to 3.2-fold. PAE exposure also stimulated the antioxidative system, with cell-normalized superoxide dismutase, catalase, and glutathione activities increasing by 1.8- to 3.0-fold, 1.0- to 2.0-fold, and 1.2- to 1.6-fold, respectively. This likely protected cells against oxidative damage by chlorine. Overall, we demonstrate that biofilm exposure to environmentally relevant levels of PAEs can upregulate molecular processes and physiologic changes that promote biofilm densification and antioxidative system expression, which enhance biofilm resistance to disinfectants.

Increased resistance to oxysterol cytotoxicity in fibroblasts transfected with a lysosomally targeted Chromobacterium oxidase.

Abstract: Ketocholesterol (7KC) is a cytotoxic oxy- sterol that plays a role in many age-related degenerative diseases. 7KC formation and accumulation often occurs in the lysosome, which hinders enzymatic transformations that reduce its toxicity and increase the sensitivity to lysosomal membrane permeabilization. We assayed the potential to mitigate 7KC cytotoxicity and enhance cell viability by overexpressing 7KC-active enzymes in human fibroblasts. One of the enzymes tested, a cholesterol oxidase engineered for lysosomal targeting, significantly increased cell viability in the short term upon treatment with up to 50 mM 7KC relative to controls. These results suggest targeting the lysosome for optimal treatment of oxysterol-mediated cy- totoxicity, and support the use of introducing novel catalytic function into the lysosome for therapeutic and research applications. Biotechnol. Bioeng. 2012;109: 2409-2415.

Ammonium Enhances Food Waste Fermentation to High-Value Optically Active l-Lactic acid

Abstract: Fermentation of food waste to l-lactic acid (l-LA), a high value-added platform molecule, is a green approach for resource recovery. However, low yield and optical activity (OA) of l-LA are key lim...

Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?

Abstract: As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...

Advanced Oxidation Processes for Organic Contaminant Destruction Based on the Fenton Reaction and Related Chemistry

Abstract: Fenton chemistry encompasses reactions of hydrogen peroxide in the presence of iron to generate highly reactive species such as the hydroxyl radical and possibly others. In this review, the complex mechanisms of Fenton and Fenton-like reactions and the important factors influencing these reactions, from both a fundamental and practical perspective, in applications to water and soil treatment, are discussed. The review covers modified versions including the photoassisted Fenton reaction, use of chelated iron, electro-Fenton reactions, and Fenton reactions using heterogeneous catalysts. Sections are devoted to nonclassical pathways, by-products, kinetics and process modeling, experimental design methodology, soil and aquifer treatment, use of Fenton in combination with other advanced oxidation processes or biodegradation, economic comparison with other advanced oxidation processes, and case studies.