Purification, molecular cloning, and expression of the gene encoding fatty acid 13-hydroperoxide lyase from guava fruit ( Psidium guajava )

Guava fruit was identified as a particularly rich source of 13-hydroperoxide lyase activity. The enzyme proved stable to chromatographic procedures and was purified to homogeneity. Based on gel filtration and gel electrophoresis, the native enzyme appears to be a homotetramer with subunits of 55 kD. Starting with primers based on the peptide sequence, the enzyme was cloned by polymerase chain reaction with 3′ and 5′ rapid amplification of cDNA ends. The sequence shows approximately 60-70% identity to known 13-hydroperoxide lyases and is classified in cytochrome P450 74B subfamily as CYP74B5. The cDNA was expressed in Escherichia coli (BL21 cells), with optimal enzyme activity obtained in the absence of isopropyl-β-d-thiogalactopyranoside and σ-aminolevulinic acid. The expressed enzyme metabolized 13(S)-hydroperoxylinolenic acid over 10-fold faster than 13(S)-hydroperoxylinoleic acid and the 9-hydroperoxides of linoleic and linolenic acids. 13(S)-Hydroperoxylinolenic acid was converted to 12-oxododec-9(Z)-enoic acid and 3(Z)-hexenal, as identified by gas chromatography-mass spectrometry. The turnover number with this substrate, with enzyme concentration estimated from the Soret absorbance, was≈2000/s, comparable to values reported for the related allene oxide synthases. Distinctive features of the guava 13-hydroperoxide lyase and related cytochrome P450 are discusse

Characterization of a multidrug resistant Citrobacter amalonaticus clinical isolate harboring blaNDM-1 and mcr-1.5 genes

A multidrug resistant isolate, identified as Citrobacter amalonaticus using MALDI-TOF MS and confirmed by genomic analysis, was recovered from a pediatric patient in a hospital from Buenos Aires, Argentina. By whole-genome sequencing a total of 16 resistance genes were detected, including blaNDM-1 and mcr-1.5. To the best of our knowledge this is the first description of these two genes together in a clinical isolate of the Citrobacter genus.Fil: Faccone, Diego Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; ArgentinaFil: Albornoz, Ezequiel Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; ArgentinaFil: Tijet, Nathalie. Public Health Ontario; CanadáFil: Biondi, Estefania. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Gómez, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; ArgentinaFil: Pasteran, Fernando. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; ArgentinaFil: Vazquez, Miryam. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Melano, Roberto Gustavo. University of Toronto; Canadá. Public Health Ontario; CanadáFil: Corso, Alejandra. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentin

New Endemic Legionella pneumophila Serogroup I Clones, Ontario, Canada

Identifying geographic distribution can improve surveillance and clinical testing procedures

Characterization of Escherichia coli Carrying mcr-1-Plasmids Recovered From Food Animals From Argentina

In this study, we found mcr-1.1 and mcr-1.5 genes carried by IncI2 plasmids in a subset of Escherichia coli isolates recovered from commercial broiler farms in Argentina. The comparative analysis of the sequences of these plasmids with those described in human clinical isolates suggests that this replicon-type is one of the main mcr-disseminator sources in Argentina

Simplified Protocol for Carba NP Test for Enhanced Detection of Carbapenemase Producers Directly from Bacterial Cultures

Fil: Pasteran, Fernando. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Bacteriología. Servicio Antimicrobianos; Argentina.Fil: Tijet, Nathalie Public Health Ontario Laboratories (PHOL); Canada.Fil: Melano, Roberto. Public Health Ontario Laboratories (PHOL, Canada Department of Laboratory Medicine and Pathobiology, University of Toronto; Canada.Fil: Corso, Alejandra. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Bacteriología. Servicio Antimicrobianos; Argentina.We compared carbapenemase detection among 266 Gram-negative bacilli (161 carbapenemase producers) using the Carba NP tests issued by the CLSI (CNPt-CLSI) and a novel protocol (CNPt-direct) designed for carbapenemase detection direct from bacterial cultures (instead of bacterial extracts required by the CLSI tests). The specificities were comparable (100%), but the CNPt-direct was more sensitive (98% versus 84%). The CNPt-direct was easier to perform due to the direct use of colonies and offered a more robust detection of carbapenemase producers