Search

Electrochemical water splitting is deemed to be an environmentally friendly methodology for hydrogen and oxygen in various electrochemical systems. The electrocatalyst has a strong relationship with the performance of the oxygen evolution reaction (OER). Herein, Co3O4 nanopolyhedrons (Co3O4 NPs) and Co3O4 nanopolyhedrons with N-doped carbon (Co3O4 NPs-NC) were obtained by changing the pyrolysis temperature using ZIF-67 as the precursor template. Due to the poor conductivity of cobalt-based oxides, the introduction of carbon nanotubes (CNTs) significantly increased the electron transfer rate of the Co3O4 polyhedron, the Co3O4 NPs-NC/CNTs exhibited outstanding activity as a catalyst in OER. The reason for the favorable catalytic capability of this catalyst is that the Co3O4 NPs-NC with dodecahedral structure can supply abundant active sites, and its plentiful mesoporous structure can facilitate the adsorption of reactants and desorption of products. Therefore, the Co3O4 NPs-NC/CNTs composite with excellent electrochemical activity has broad application prospects as a promising catalyst. The excellent OER performance of Co3O4 NPs-NC/CNTs is attributed to having a polyhedral structure that replicates the ZIF-67 morphology and its rich mesoporous structure, which can provide more effective active sites. [ABSTRACT FROM AUTHOR]

This study presents three novel integrons In1394, In1395, and In1443, three novel unit transposons Tn 6392 , Tn 6393 , and Tn 6403 , one novel conjugative element (ICE) Tn 6413 , and the first sequenced IncP-7 resistance plasmid p1160-VIM from clinical Pseudomonas aeruginosa. Detailed sequence comparison of p1160-VIM (carrying Tn 6392 and Tn 6393) and Tn 6413 (carrying Tn 6403) with related elements were performed. Tn 6392 , Tn 6393 , and Tn 6403 were generated from integration of In1394 (carrying bla VIM–24), In1395 and In1443 (carrying bla VIM–4) into prototype Tn 3 -family unit transposons Tn 5563 , Tn 1403 , and Tn 6346 , respectively. To the best of our knowledge, this is the first report of a bla VIM–24-carrying P. aeruginosa isolate. [ABSTRACT FROM AUTHOR]

Background: IncR, IncFII, IncpA1763-KPC, and IncN1 plasmids have been increasingly found among Enterobacteriaceae species, but plasmids with hybrid structures derived from the above-mentioned incompatibility groups have not yet been described. Methods: Plasmids p721005-KPC, p504051-KPC, and pA3295-KPC were fully sequenced and compared with previously sequenced related plasmids pHN84KPC (IncR), pKPHS2 (IncFIIK), pKOX_NDM1 (IncFIIY), pHN7A8 (IncFIIpHN7A8), and R46 (IncN1). Results: The backbone of p721005-KPC/p504051-KPC was a hybrid of the entire 10-kb IncR-type backbone from pHN84KPC, the entire 64.3-kb IncFIIK-type maintenance, and conjugal transfer regions from pKPHS2, a 15.5-kb IncFIIY-type maintenance region from pKOX_NDM1 and a 5.6-kb IncpA1763-KPC-type backbone region from pA1763-KPC, and it contained a primary IncR replicon and two auxiliary IncpA1763-KPC and IncN1 replicons. The backbone of pA3295-KPC was a hybrid of a 7.2-kb IncFIIpHN7A8-type backbone region from pHN7A8, the almost entire 33.3-kb IncN1-type maintenance and conjugal transfer regions highly similar to R46, a 26.2-kb IncFIIK-type maintenance regions from pKPHS2, the above 15.5-kb IncFIIY-type maintenance region, and the above 5.6-kb IncpA1763-KPC-type backbone region, and it contained a primary IncFIIpHN7A8 replicon and two auxiliary IncpA1763-KPC and IncN1 replicons. Each of p721005-KPC, p504051-KPC, and pA3295-KPC acquired a wealth of accessory modules, carrying a range of intact and residue mobile elements (such as insertion sequences, unit transposons, and integrons) and resistance markers (such as blaKPC, tetA, dfrA, and qnr). Conclusion: In each of p721005-KPC, p504051-KPC, and pA3295-KPC, multiple replicons in coordination with maintenance and conjugation regions of various origins would maintain a broad host range and a stable replication at a steady-state plasmid copy number. [ABSTRACT FROM AUTHOR]

The quinolone resistance crpP genes can mediate decreased susceptibility to quinolones. However, diversification and prevalence of crpP genes and crpP -carrying integrative and conjugative elements (ICEs) still need to be elucidated. In this study, genome sequencing was conducted for 200 Chinese Pseudomonas aeruginosa isolates, 16 of which were fully sequenced. All the 37 available CrpP variants were collected for phylogenetic analysis, 10 CrpP enzymes were chosen to conduct cloning and antimicrobial susceptibility test, and 22 crpP -carrying Tn 6786 -related ICEs were selected for detail genetic dissection analysis. Then, typing/nomenclature schemes for crpP variants and crpP -carrying ICEs were established for the first time. The 10 representative CrpP enzymes were confirmed to mediate decreased susceptibility to one to three quinolones. Tn 6786 -related ICEs displayed high-level diversification in both nucleotide sequences and modular structures. Mainly, massive gene acquisition/loss occurred across the whole genomes of Tn 6786 -related ICEs. 53.5% (107/200) of the tested clinical P. aeruginosa isolates from China carried crpP genes, which were exclusively located within chromosome-borne Tn 6786 -related ICEs. The crpP -carrying ICEs were at active stages of evolution and had the high potential to be an important vector for the dissemination of resistance genes besides crpP . The present study furthered the understanding of the bioinformatics and epidemiology of crpP genes and crpP -carrying ICEs.

This study presents three novel integrons In1394, In1395, and In1443, three novel unit transposons Tn 6392 , Tn 6393 , and Tn 6403 , one novel conjugative element (ICE) Tn 6413 , and the first sequenced IncP-7 resistance plasmid p1160-VIM from clinical Pseudomonas aeruginosa . Detailed sequence comparison of p1160-VIM (carrying Tn 6392 and Tn 6393 ) and Tn 6413 (carrying Tn 6403 ) with related elements were performed. Tn 6392 , Tn 6393 , and Tn 6403 were generated from integration of In1394 (carrying bla VIM-24 ), In1395 and In1443 (carrying bla VIM-4 ) into prototype Tn 3 -family unit transposons Tn 5563 , Tn 1403 , and Tn 6346 , respectively. To the best of our knowledge, this is the first report of a bla VIM-24 -carrying P. aeruginosa isolate.