The Hidden Quantum Groups Symmetry of Super-renormalizable Gravity

In this paper we consider the relation between the super-renormalizable theories of quantum gravity (SRQG) studied in [arXiv:1110.5249v2, arXiv:1202.0008] and an underlying non-commutativity of spacetime. For one particular super-renormalizable theory we show that at linear level (quadratic in the Lagrangian) the propagator of the theory is the same we obtain starting from a theory of gravity endowed with {\theta}-Poincar\'e quantum groups of symmetry. Such a theory is over the so called {\theta}-Minkowski non-commuative spacetime. We shed new light on this link and show that among the theories considered in [arXiv:1110.5249v2, arXiv:1202.0008], there exist only one non-local and Lorentz invariant super-renormalizable theory of quantum gravity that can be described in terms of a quantum group symmetry structure. We also emphasize contact with pre-existent works in the literature and discuss preservation of the equivalence principle in our framework.Comment: 10 page

High-flux isobutanol production using engineered Escherichia coli: a bioreactor study with in situ product removal

Promising approaches to produce higher alcohols, e.g., isobutanol, using Escherichia coli have been developed with successful results. Here, we translated the isobutanol process from shake flasks to a 1-L bioreactor in order to characterize three E. coli strains. With in situ isobutanol removal from the bioreactor using gas stripping, the engineered E. coli strain (JCL260) produced more than 50 g/L in 72 h. In addition, the isobutanol production by the parental strain (JCL16) and the high isobutanol-tolerant mutant (SA481) were compared with JCL260. Interestingly, we found that the isobutanol-tolerant strain in fact produced worse than either JCL16 or JCL260. This result suggests that in situ product removal can properly overcome isobutanol toxicity in E. coli cultures. The isobutanol productivity was approximately twofold and the titer was 9% higher than n-butanol produced by Clostridium in a similar integrated system

Dioxygen Activation by Laccases: Green Chemistry for Fine Chemical Synthesis

Laccases are enzymes with attractive features for the synthesis of fine chemicals. The friendly reaction conditions of laccases and their high conversion and selectivity make them particularly suitable for green methods of synthesis. In addition, laccases are enzymes with broad substrate variability, ease of production, and no need of cofactors or aggressive oxidizing agents. Among molecules oxidized by laccases are polycyclic aromatic hydrocarbons, azo dyes, pesticides, phenols, and pharmaceuticals. This article reviews the laccase-mediated oxidation of fine chemicals for the production of biologically active compounds. The main aspects of the enzymatic oxidation are summarized; potentials and limitations are identified and proposals to develop more robust catalysts are analyzed

Los metales pesados en la historia de la humanidad, los efectos de la contaminación por metales pesados y los procesos biotecnológicos para su eliminación: el caso de Bacillus como bioherramienta para la recuperación de suelos

El término “metales pesados” se refiere al grupo de metales con número atómico superior a 20 y caracterizados por una densidad atómica mayor a 5 g·cm-3. Los metales pesados son elementos naturales de la corteza terrestre, y su distribución es dada por fuentes geogénicas. Los metales pesados son de suma importancia para el mundo moderno, y requeridos en grandes cantidades por la sociedad actual; sin embargo, se caracterizan por sus efectos tóxicos, y son peligrosos porque tienden a bioacumularse, lo que significa un aumento en la concentración de éstos en los organismos. La contaminación del ambiente por metales pesados involucra actividades antropogénicas como la agricultura, minería, fundiciones, plantas de energía y diversas industrias (petroquímica, textil o de componentes electrónicos). Esta problemática se ha intentado resolver por medio de tecnologías que no han logrado el objetivo deseado. La aplicación de herramientas biotecnológicas abre una gran posibilidad de encontrar soluciones plausibles a problemas de contaminación. El género Bacillus es un grupo bacteriano de relevancia en diferentes áreas como la medicina, la agricultura y la industria; y en el área biotecnológica se ha utilizado para la biorremediación. Diferentes estudios han mostrado el gran potencial de este grupo microbiano para resolver, de una manera amigable para el ambiente y efectiva, los problemas de contaminación del ambiente por metales pesados. En la presente revisión se aborda la temática de los metales pesados en la historia de la humanidad, los efectos de la contaminación por metales pesados y los procesos biotecnológicos para su eliminación; considerando el caso de Bacillus como bioherramienta para la recuperación de suelos contaminados con metales pesados

The importance of antimicrobial compounds produced by beneficial bacteria on the biocontrol of phytopathogens

Bacteria produce antimicrobial compounds to compete for nutrients and space in a particular habitat. Antagonistic interactions can be evaluated by several methodologies including the double-layer agar and simultaneous inhibition assays. Among the well-known inhibitory substances produced by bacteria are the broad-spectrum antibiotics, organic acids, siderophores, antifungal, and bacteriocins. The most studied bacterial genera able to produce these inhibitory substances are Enterococcus, Lactococcus, Streptomyces, Bacillus, Pseudomonas, Klebsiella, Escherichia, and Burkholderia. Some beneficial bacteria can promote plant growth and degrade toxic compounds in the environment representing an attractive solution to diverse issues in agriculture and soil pollution, particularly in fields with damaged soils where pesticides and fertilizers have been indiscriminately used. Beneficial bacteria may increase plant health by inhibiting pathogenic microorganisms; some examples include Gluconacetobacter diazotrophicus, Azospirullum brasilense, Pseudomonas fluorescens, Pseudomonas protegens, and Burkholderia tropica. However, most studies showing the antagonistic potential of these bacteria have been performed in vitro, and just a few of them have been evaluated in association with plants. Several inhibitory substances involved in pathogen antagonism have not been elucidated yet; in fact, we know only 1 % of the bacterial diversity in a natural environment leading us to assume that many other inhibitory substances remain unexplored. In this review, we will describe the characteristics of some antimicrobial compounds produced by beneficial bacteria, the principal methodologies performed to evaluate their production, modes of action, and their importance for biotechnological purposes

Inoculante de segunda generación para incrementar el crecimiento y salud de plantas de jardín

Las bacterias promotoras del crecimiento de plantas han sido extensamente estudiadas y recientemente se han diseñado formulaciones multiespecies de segunda generación. Una de las formulaciones se denomina INOCREP y está compuesta por 6 especies bacterianas benéficas. INOCREP estimula el crecimiento de plantas mucho mejor que los monoinoculantes y se ha explorado su función en diversas plantas de interés agrícola. Una formulación derivada de INOCREP que está diluida 10 veces respecto a la formulación original, se ha propuesto como una formulación para jardín; esta se ha explorado en diversas plantas bajo condición de maceta, permitiendo a las plantas un buen desarrollo. Existen tres formas para inocular las bacterias de la formulación multiespecies en jardines: a nivel de semilla, a nivel de plántula y a nivel de plantas desarrollas. En este trabajo se muestra un panorama del estado del arte de la formulación INOCREP y su derivado de jardín

Structural characterization of scorpion peptides and their bactericidal activity against clinical isolates of multidrug-resistant bacteria.

Scorpion venom peptides represent a novel source of antimicrobial peptides (AMPs) with broad-spectrum activity. In this study, we determined the minimum bactericidal concentration (MBC) of three scorpion AMPs, Uy234, Uy17, and Uy192, which are found in the venomous glands of the Urodacus yaschenkoi scorpion, against the clinical isolates of multidrug-resistant (MDR) bacteria. In addition, we tested the activity of a consensus AMP designed in our laboratory based on some previously reported IsCT-type (cytotoxic linear peptide) AMPs with the aim of obtaining higher antimicrobial activity. All peptides tested showed high antimicrobial activity against MDR clinical isolates, with the highest activity against β-hemolytic Streptococcus strains. The hemolytic activity was determined against human red blood cells and was significantly lower than that of previously reported AMPs. The α-helical structure of the four AMPs was confirmed by circular dichroism (CD). These results suggest that the four peptides can be valuable tools for the design and development of AMPs for use in the inhibition of MDR pathogenic bacteria. A clear index of synergism and additivity was found for the combination of QnCs-BUAP + Uy234, which makes these peptides the most promising candidates against pathogenic bacteria

Growth inhibition of pathogenic microorganisms by Pseudomonas protegens EMM-1 and partial characterization of inhibitory substances.

The bacterial strain, EMM-1, was isolated from the rhizosphere of red maize ("Rojo Criollo") and identified as Pseudomonas protegens EMM-1 based on phylogenetic analysis of 16S rDNA, rpoB, rpoD, and gyrB gene sequences. We uncovered genes involved in the production of antimicrobial compounds like 2,4-diacetylphloroglucinol (2,4-DAPG), pyoluteorin, and lectin-like bacteriocins. These antimicrobial compounds are also produced by other fluorescent pseudomonads alike P. protegens. Double-layer agar assay showed that P. protegens EMM-1 inhibited the growth of several multidrug-resistant (MDR) bacteria, especially clinical isolates of the genera Klebsiella and β-hemolytic Streptococcus. This strain also displayed inhibitory effects against diverse fungi, such as Aspergillus, Botrytis, and Fusarium. Besides, a crude extract of inhibitory substances secreted into agar was obtained after the cold-leaching process, and physicochemical characterization was performed. The partially purified inhibitory substances produced by P. protegens EMM-1 inhibited the growth of Streptococcus sp. and Microbacterium sp., but no inhibitory effect was noted for other bacterial or fungal strains. The molecular weight determined after ultrafiltration was between 3 and 10 kDa. The inhibitory activity was thermally stable up to 60°C (but completely lost at 100°C), and the inhibitory activity remained active in a wide pH range (from 3 to 9). After treatment with a protease from Bacillus licheniformis, the inhibitory activity was decreased by 90%, suggesting the presence of proteic natural compounds. All these findings suggested that P. protegens EMM-1 is a potential source of antimicrobials to be used against pathogens for humans and plants