Pseudomonas aeruginosa is a significant human pathogen, it possesses almost all of the known antimicrobial resistance mechanisms. Quorum sensing (QS) is an intercellular communication system that orchestrates bacterial virulence and its targeting is an effective approach to diminish its pathogenesis. Repurposing of drugs is an advantageous strategy, in this study we aimed to repurpose the anti-diabetic drugs sitagliptin, metformin and vildagliptin as anti-QS in P. aeruginosa. The effects of sub-inhibitory concentrations of the tested drugs on the expression of QS-encoding genes and QS-regulated virulence factors were assessed. The protective activity of tested drugs on P. aeruginosa pathogenesis was evaluated in vivo on mice. In silico analysis was performed to evaluate the interference capabilities of the tested drugs on QS-receptors. Although the three drugs reduced the expression of QS-encoding genes, only sitagliptin inhibited the P. aeruginosa virulence in vitro and protected mice from it. In contrast, metformin showed significant in vitro anti-QS activities but failed to protect mice from P. aeruginosa. Vildagliptin did not show any in vitro or in vivo efficacy. Sitagliptin is a promising anti-QS agent because of its chemical nature that hindered QS-receptors. Moreover, it gives an insight to consider their similar chemical structures as anti-QS agents or even design new chemically similar anti-QS pharmacophores.

Repurposing Anti-diabetic Drugs to Cripple Quorum Sensing in Pseudomonas aeruginosa.

由尖镰孢菌（FusariumoxysporumSchlecht．）引起的大豆枯萎病是危害大豆生产的主要土传病害。该菌在土壤和病残体上均可长期生存造成危害。快速准确地在发病初期植株和带病土壤中进行鉴定和检测对防治该病害至关重要。

尖镰孢菌（Fusarium oxysporum）的快速分子检测

Heavy metal accumulation in mesquite trees (Prosopis laevigata) growing in aluminum, titanium, chromium and zirconium-polluted soils of a semi-arid region in Mexico was investigated using wavelength dispersive X-ray fluorescence analysis. The results showed that P. laevigata trees can hyper accumulate up to 4100 mg/kg of Al, 14000 mg/kg of Fe, 1600 mg/kg of Ti, 2500 mg/kg of Zn, but not chromium, regarding high chromium concentrations found in soils (435 mg/kg). Since plant-associated microorganism can modulate phytoremediation efficiency, the biodiversity of P. laevigata associated bacteria was studied. Eighty-eight isolates from P. laevigata nodules were obtained; all isolates tolerated high concentrations of Al, Fe, Zn and Cr in vitro. The top-six chromium tolerant strains were identified by 16S rRNA sequence analysis as belonging to genus Bacillus. Bacillus sp. MH778713, close to Bacillus cereus group, showed to be the most resistant strain, tolerating up to 15000 mg/L Cr (VI) and 10000 mg/L of Al. Regarding the bioaccumulation traits, Bacillus sp. MH778713 accumulated up to 100 mg Cr(VI)/g of cells when it was exposed to 1474 mg/L of Cr VI. To assess Bacillus sp. MH778713 ability to assist Prosopis laevigata phytoremediation; twenty plants were inoculated or non-inoculated with Bacillus sp. MH778713 and grown in nitrogen-free Jensen's medium added with 0, 10 and 25 mg/L of Cr(VI). Only plants inoculated with Bacillus sp. grew in the presence of chromium showing the ability of this strain to assist chromium phytoremediation. P. laevigata and Bacillus spp. may be considered as good candidates for soil restoration of arid and semiarid sites contaminated with heavy metals.

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Chromium Hyper-Tolerant Bacillus sp. MH778713 Assists Phytoremediation of Heavy Metals by Mesquite Trees (Prosopis laevigata).

Alleviation of the toxicity of oily wastewater to canola plants by the N2-fixing, aromatic hydrocarbon biodegrading bacterium Stenotrophomonas maltophilia-SR1

The effect of EDTA and citric acid on biochemical processes and changes in phenolic compounds profile of okra (Abelmoschus esculentus L.) under mercury stress.

The ability of Bacillus subtilis, strain ALICA to produce three mycolytic enzymes (chitinase, β-1,3-glucanase, and protease), was carried out by the chemical standard methods. Bacillus subtilis ALICA was screened based on their antifungal activity in dual plate assay and cell-free culture filtrate (25%) against five different phytopathogenic fungi Alternaria alternata, Macrophomina sp., Colletotrichum gloeosporioides, Botrytis cinerea, and Sclerotium rolfesii. The B. subtilis ALICA detected positive for chitinase, β-1,3-glucanase and protease enzymes. Fungal growth inhibition by both strain ALICA and its cell-free culture filtrate ranged from 51.36% to 86.3% and 38.43% to 68.6%, respectively. Moreover, hyphal morphological changes like damage, broken, swelling, distortions abnormal morphology were observed. Genes expression of protease, β-1,3-glucanase, and lipopeptides (subtilosin and subtilisin) were confirmed their presence in the supernatant of strain ALICA. Our findings indicated that strain ALICA provided a broad spectrum of antifungal activities against various phytopathogenic fungi and may be a potential effective alternative to chemical fungicides.

Antifungical Activity of Autochthonous Bacillus subtilis Isolated from Prosopis juliflora against Phytopathogenic Fungi.

The aim of the present work is to evaluate the changes on the phenylalanine ammonia lyase (PAL) activity, phenolic compounds accumulation and photochemical efficiency in leaves of P. glandulosa treated with Cd2+ (0.001 M) and Cu2+ (0.52 M) concentrations for 96 h under hydroponic conditions. The results showed that only leaves treated with copper had a decrease in photochemical efficiency and leaf epidermal polyphenols in P. glandulosa leaves after 96 h of exposure. On the other hand the reverse-phase HPLC analysis revealed higher levels of phenolic compound (gallic, vanillic and caffeic acids) and flavonoids (rutin and kaempferol-3-O-glucosides) in plant leaves from Cu and Cd-treatments with respect to control plants. Finally, highest increments in PAL activity was observed in extracts of leaves treated with Cu and Cd (about 205 and 284%), respectively, with respect to control plants after 96 h treatment. These suggest that activation of phenylpropanoid pathway represent a source of nonenzymatic antioxidants that protect at P. glandulosa against oxidative stress when exposed to cadmium and copper. Hence future studies are necessary to elucidate the participation of phenylpropanoid pathway in the reduction of metal toxicity in Prosopis species.

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Changes in the phenylalanine ammonia lyase activity, total phenolic compounds, and flavonoids in Prosopis glandulosa treated with cadmium and copper

Cotton production in the Mexicali valley is adversely affected by wilt and root rot disease associated with Fusarium species. In the present study, we sought to isolate and identify the Fusarium species in the rhizosphere of transgenic insect-resistant cotton plants grown in the Mexicali valley. Our analyses isolated four native fungi from the rhizosphere of cotton plants, namely, T-ICA01, T-ICA03, T-ICA04, and T-ICA08. These fungal isolates were categorized as belonging to Fusarium solani using their phenotypic characteristics and ITS region sequence data. Examination of the infection index showed that T-ICA03 and T-ICA04 caused systemic colonization (90%) of seeds followed by the occurrence of radicle and coleoptile decay. In contrast, T-ICA08 strain was less pathogenic against seed tissues (40%) in comparison to the other strains isolated. Our study showed that in transgenic insect-resistant cotton the disease "Fusarium wilt" is caused by the fungus, F. solani. Future studies are necessary to characterize the F. solani populations to determine whether phenological stages might influence the genetic diversity of the fungal populations present.

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Molecular identification of Fusarium species isolated from transgenic insect-resistant cotton plants in Mexicali valley, Baja California.

espanolEl objetivo del presente estudio fue evaluar la actividad de las enzimas fenilalanina amonio-liasa (PAL), peroxidasa (POX) y la produccion de compuestos fenolicos y flavonoides en plantas de algodon transgenico en respuesta a la inoculacion con Trichoderma longibrachiatum (ICA-4). Noventa dias despues de la inoculacion con T. longibrachiatum, hojas de las plantas de algodon fueron colectadas y las enzimas PAL, POX y los compuestos fenolicos fueron determinados. Los resultados mostraron que la inoculacion aumento el contenido de compuestos fenolicos y flavonoides en 18% y 45%, respectivamente; comparadas con plantas no inoculadas. La actividad de las enzimas peroxidasa (4,88 Ux10-5/mg de proteina), y fenilalanina amonia-liasa (0,0176 U/mg de proteina) mostraron diferencias significativas en comparacion con la actividad enzimatica de plantas no inoculadas (3,48x10-5 U/mg proteina para POX y 0,01 U/mg de proteina para PAL). Estos resultados sugieren la induccion de una respuesta de resistencia sistemica inducida por la inoculacion de las semillas con la cepa Trichoderma ICA-4. EnglishThe objective of the present study was to evaluate the activity of phenylalanine ammonia-lyase (PAL), peroxidase (POX) and the production of phenolic compounds and flavonoids in transgenic cotton plants in response to inoculation with Trichoderma longibrachiatum (ICA-4). Ninety days after inoculation with T. longibrachiatum, leaves of the cotton plants were collected and the enzymes PAL, POX and phenolic compounds were determined. The results showed that inoculation increased the content of phenolic compounds and flavonoids by 18% and 45%, respectively, compared to non-inoculatedplants. The activity of the enzymes peroxidase (4.88 Ux10-5/mg protein), and phenylalanine ammonia-lyase (0.0176 U/mg protein) showed significant differences compared to the enzymatic activity of uninoculated plants (3, 48x10-5 U/mg proteinfor POX and 0.01 U/mg proteinfor PAL). These results suggest the induction of a systemic resistance response induced by seed inoculation with the Trichoderma ICA-4 strain.

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Tania Elisa González-Soto

Papers

Antifungical Activity of Autochthonous Bacillus subtilis Isolated from Prosopis juliflora against Phytopathogenic Fungi.

Changes in the phenylalanine ammonia lyase activity, total phenolic compounds, and flavonoids in Prosopis glandulosa treated with cadmium and copper

Molecular identification of Fusarium species isolated from transgenic insect-resistant cotton plants in Mexicali valley, Baja California.

Inoculación de Trichoderma longibrachiatum en algodón transgénico: Cambios en compuestos fenólicos y enzimas de estrés oxidativo

Inoculation of Trichoderma longibrachiatum in transgenic cotton: change in the phenolics compounds and enzymes of oxidative stress.