La quema del tamo de arroz a campo abierto es una de las mayores fuentes de contaminacion agricola, es por esto que el retorno de los residuos vegetales al suelo ha sido propuesto como una alternativa de manejo eficiente de los residuos pos-cosecha. Sin embargo, es poco conocido el impacto que tiene sobre los microorganismos edaficos involucrados en la disponibilidad y ciclaje de nutrientes. Por lo anterior, se planteo un experimento en campo para evaluar los cambios generados sobre la comunidad microbiana vinculada al ciclo del nitrogeno por la aplicacion de 4 tratamientos diferentes de manejo del tamo de arroz: (Cob+mo) cobertura del terreno con tamo de arroz inoculado con un consorcio microbiano de degradacion, (Inc+mo) tamo de arroz inoculado con el consorcio microbiano e incorporado, (Quema) quema del tamo y (Cob) cobertura del terreno con tamo de arroz sin inocular. Se realizaron 4 muestreos de suelo de soporte y suelo rizosferico antes y durante el ciclo de cultivo. Se evaluo la diversidad, estructura y composicion de la comunidad bacteriana a traves del analisis del gen 16S rRNA y se determino la actividad de las enzimas nitrogenasa, proteasa y ureasa vinculadas con el ingreso de nitrogeno al sistema edafico. Al final del ciclo de cultivo, los mapas de calor basados en la composicion y abundancia de especies, mostraron que las comunidades microbianas de los tratamientos alternos a la quema son mas similares entre si, indicando que la adicion de materia organica influencia la comunidad edafica microbiana. La actividad de las enzimas proteasa y ureasa se vio afectada por la aplicacion del consorcio de degradacion y la forma de retorno del tamo de arroz al suelo respectivamente. 
 
 
Palabras clave: (Incorporacion, cobertura, tamo de arroz, actividad enzimatica, 16S rRNA).

Evaluación de la diversidad taxonómica y funcional de la comunidad microbiana relacionada con el ciclo del nitrógeno en suelos de cultivo de arroz con diferentes manejos del tamo

Fig.4. Neutralization by donor and pooled subtype C plasma. (A) Neutralization profile of plasma-derived donor (green) and recipient (blue) Env pseudotypes from transmission pair 135 by donor plasma. Virus infectivity, as a percentage of the control, is plotted along the vertical axis. The reciprocal of the plasma dilution is graphed along the horizontal axis on a log 10 scale. Each curve represents the sensitivity to neutralization of an individual Env pseudotype. (B) The distribution of neutralization sensitivity for donor (green) and recipient (blue) Env pseudotypes for five transmission pairs, with IC 50 values for donor plasma (rounded to the nearest two-digit value) plotted on the horizontal axis. The fraction of Env pseudotypes with a given IC 50 is indicated on the vertical axis. (C) Linear regression analysis of neutralization by donor (horizontal axis) and pooled (vertical axis) plasma for donor (green) and recipient (blue) Env pseudotypes (R-squared value 0.23; P value 0.00002; slope 0.31, standard error 0.07). The number of Env pseudotypes evaluated was 106 (5 donor and 7 recipient), 109 (8 donor and 3 recipient), 135 (14 donor and 5 recipient), 55 (12donor and 8 recipient), and 53 (6 donor and 3 recipient). R EPORTS

A MicroRNA as a Translational Repressor of APETALA2 in Arabidopsis Flower Development

Nanomedicine and advanced technologies for burns: Preventing infection and facilitating wound healing.

Alarming data about increasing resistance to conventional antibiotics are reported, while at the same time the development of new antibiotics is stagnating. Skin and soft tissue infections (SSTIs) are mainly caused by the so called ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) which belong to the most recalcitrant bacteria and are resistant to almost all common antibiotics. S. aureus and P. aeruginosa are the most frequent pathogens isolated from chronic wounds and increasing resistance to topical antibiotics has become a major issue. Therefore, new treatment options are urgently needed. In recent years, research focused on the development of synthetic antimicrobial peptides (AMPs) with lower toxicity and improved activity compared to their endogenous counterparts. AMPs appear to be promising therapeutic options for the treatment of SSTIs and wounds as they show a broad spectrum of antimicrobial activity, low resistance rates and display pivotal immunomodulatory as well as wound healing promoting activities such as induction of cell migration and proliferation and angiogenesis. In this review, we evaluate the potential of AMPs for the treatment of bacterial SSTIs and wounds and provide an overview of the mechanisms of actions of AMPs that contribute to combat skin infections and to improve wound healing. Bacteria growing in biofilms are more resistant to conventional antibiotics than their planktonic counterparts due to limited biofilm penetration and distinct metabolic and physiological functions, and often result in chronification of infections and wounds. Thus, we further discuss the feasibility of AMPs as anti-biofilm agents. Finally, we highlight perspectives for future therapies and which issues remain to bring AMPs successfully to the market.

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Antimicrobial Peptides and Their Therapeutic Potential for Bacterial Skin Infections and Wounds.

Overuse of conventional antibiotics as well as the slow pace of new antibiotic drug development leads to antimicrobial resistance (AMR). Because infections with multi‐drug resistant (MDR) pathogens have become a public health issue, the need for a novel class of antibiotics is urgent. Recently, antimicrobial peptides (AMPs) have emerged as a promising platform to fight against MDR bacteria ensuring broad‐spectrum antimicrobial activity and relatively low resistance emergence. Currently, a number of AMPs are undergoing clinical and preclinical trials against various infectious diseases. This review lists the 36 AMPs (27 clinical and 9 preclinical) with brief information about their origin, structure, mechanism, and development status. From the examples of AMPs under clinical investigation, we categorized several improvement strategies and highlighted directions for the future design of AMPs.

Antimicrobial peptides under clinical investigation

Methicillin-resistant Staphylococcus aureus (MRSA) infections present a serious challenge because of the emergence of resistance to numerous conventional antibiotics. Due to their unique mode of action, antimicrobial peptides are novel alternatives to traditional antibiotics for tackling the issue of bacterial multidrug resistance. Herein, we investigated the antibacterial activity of two short novel peptides (WR12, a 12 residue peptide composed exclusively of arginine and tryptophan, and D-IK8, an eight residue β-sheet peptide) against multidrug resistant staphylococci. In vitro, both peptides exhibited good antibacterial activity against MRSA, vancomycin-resistant S. aureus, linezolid-resistant S. aureus, and methicillin-resistant S. epidermidis. WR12 and D-IK8 were able to eradicate persisters, MRSA in stationary growth phase, and showed significant clearance of intracellular MRSA in comparison to both vancomycin and linezolid. In vivo, topical WR12 and D-IK8 significantly reduced both the bacterial load and the levels of the pro-inflammatory cytokines including tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in MRSA-infected skin lesions. Moreover, both peptides disrupted established in vitro biofilms of S. aureus and S. epidermidis significantly more so than traditional antimicrobials tested. Taken together, these results support the potential of WR12 and D-IK8 to be used as a topical antimicrobial agent for the treatment of staphylococcal skin infections.

Evaluation of short synthetic antimicrobial peptides for treatment of drug-resistant and intracellular Staphylococcus aureus

Globally, plant viral infection is one of the most difficult challenges of food security, where considerable losses in crop production occur. Nanoparticles are an effective control agent against numerous plant pathogens. However, there is limited knowledge concerning their effects against viral infection. In the present study, the green synthesis of zinc oxide nanoparticles (ZnO NPs) using aqueous leaf extract of Mentha spicata was achieved. X-ray diffraction patterns confirmed the crystalline nature of the prepared ZnO NPs. Dynamic light scattering and scanning electron microscopy analyses revealed that the resultant ZnO NPs were spherical in shape with a particle size ranged from 11 to 88 nm. Fourier transmission infrared spectroscopy detected different functional groups, capping and stability agents, and showed Zn-O bond within wavenumber of 487 cm−1. Under greenhouse conditions, the antiviral activity of biological synthesized ZnO NPs (100 µg/mL) against Tobacco mosaic virus (TMV) was evaluated. The double foliar application of the prepared ZnO NPs, 24 h before and 24 h after TMV-inoculation, was the most effective treatment that showed a 90.21% reduction of viral accumulation level and disease severity. Additionally, the transcriptional levels of PAL, PR-1 (salicylic acid marker gene), CHS, and POD genes were induced and up-regulated in all ZnO NPs treated plants. Notably, the results exhibited that aqueous extract of Mentha spicata was an effective reducing agent for the green synthesis of ZnO NPs, which showed significant antiviral activity. Finally, the detected protective and curative activity of ZnO NPs against TMV can encourage us to recommend its application for plant viral disease management. To our knowledge, this is the first study describing the antiviral activity of the green synthesized ZnO NPs.

Green Synthesized ZnO Nanoparticles Mediated by Mentha Spicata Extract Induce Plant Systemic Resistance against Tobacco Mosaic Virus

The Rhizobia are collectively comprised of gram negative soil bacteria that have the ability to form symbiotic nitrogen-fixing root and/or stem nodules in association with leguminous plants. The taxonomy of these bacteria is continually in a state of flux, in large part due to rapid development of refined molecular biology techniques. The isolation and characterization of new, and often different, legumes-nodulating bacteria on a variety of plant hosts has resulted in the naming of many new rhizobial species. Here we update the taxonomy of the legume-nodulating bacteria and describe newly identified rhizobia capable of nodulating edible legumes and legume trees. In 1990, there was only one bacterial species that was known to nodulate common bean worldwide (Rhizobium leguminosarum sv. phaseoli), one species that nodulated faba bean (Rhizobium leguminosarum sv. viciae), and two species that nodulated soybean (Bradyrhizobium japonicum and Rhizobium fredii). Today, nearly 14, 11, 6, 5, 5, 4, 3 and 2 species have been defined that are capable of nodulating common bean, soybean, cowpea, chickpea, peanut, lentils, faba bean and pea, respectively. The recent use of whole genome based taxonomy (genomotaxonomy) will surely change how we define this important group of bacteria. The identification of several rhizobial species that are able to nodulate and fix nitrogen with edible legumes may enhance the production of these crops and can compensate for worldwide deficiencies in human nutritional needs in the future.

Recent changes to the classification of symbiotic, nitrogen-fixing, legume-associating bacteria: a review

Multidrug-resistant enterococcal pathogens, especially vancomycin-resistant enterococci (VRE), are among the pathogens that require new antibiotic innovation. The colonization of the gut represents a major pathway by which VRE can cause infection and spread to other patients. In the current study, auranofin (FDA-approved rheumatoid arthritis drug) is evaluated for its potential use as a decolonizing agent for VRE. Auranofin was found to exert potent antimicrobial activity against a wide range of enterococcal clinical isolates with a minimum inhibitory concentration of 1 μg/mL. No resistant mutants could be developed against auranofin over the course of 14 passages. Auranofin was also found to exert potent anti-biofilm activity against VRE. Auranofin was superior to linezolid, the drug of choice for VRE infection treatment, in the in vivo mouse model. Auranofin significantly reduced the VRE burden in feces, cecum, and ileum contents after 8 days of treatment. Accordingly, this study provides valuable evidence that auranofin has significant promise as a novel gastrointestinal decolonizing agent for VRE.

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Ahmed Abdelkhalek

Papers

Evaluation of short synthetic antimicrobial peptides for treatment of drug-resistant and intracellular Staphylococcus aureus

Green Synthesized ZnO Nanoparticles Mediated by Mentha Spicata Extract Induce Plant Systemic Resistance against Tobacco Mosaic Virus

Recent changes to the classification of symbiotic, nitrogen-fixing, legume-associating bacteria: a review

Repurposing auranofin as an intestinal decolonizing agent for vancomycin-resistant enterococci.

Antiviral, antifungal, and insecticidal activities of Eucalyptus bark extract: HPLC analysis of polyphenolic compounds.