72 research outputs found
New Insights into the Bacterial Fitness-Associated Mechanisms Revealed by the Characterization of Large Plasmids of an Avian Pathogenic E. coli
Extra-intestinal pathogenic E. coli (ExPEC), including avian pathogenic E. coli (APEC), pose a considerable threat to both human and animal health, with illness causing substantial economic loss. APEC strain χ7122 (O78∶K80∶H9), containing three large plasmids [pChi7122-1 (IncFIB/FIIA-FIC), pChi7122-2 (IncFII), and pChi7122-3 (IncI(2))]; and a small plasmid pChi7122-4 (ColE2-like), has been used for many years as a model strain to study the molecular mechanisms of ExPEC pathogenicity and zoonotic potential. We previously sequenced and characterized the plasmid pChi7122-1 and determined its importance in systemic APEC infection; however the roles of the other pChi7122 plasmids were still ambiguous. Herein we present the sequence of the remaining pChi7122 plasmids, confirming that pChi7122-2 and pChi7122-3 encode an ABC iron transport system (eitABCD) and a putative type IV fimbriae respectively, whereas pChi7122-4 is a cryptic plasmid. New features were also identified, including a gene cluster on pChi7122-2 that is not present in other E. coli strains but is found in Salmonella serovars and is predicted to encode the sugars catabolic pathways. In vitro evaluation of the APEC χ7122 derivative strains with the three large plasmids, either individually or in combinations, provided new insights into the role of plasmids in biofilm formation, bile and acid tolerance, and the interaction of E. coli strains with 3-D cultures of intestinal epithelial cells. In this study, we show that the nature and combinations of plasmids, as well as the background of the host strains, have an effect on these phenomena. Our data reveal new insights into the role of extra-chromosomal sequences in fitness and diversity of ExPEC in their phenotypes
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Photocatalytic CO<inf>2</inf> reduction
Using sunlight to power CO2 conversion into value-added chemicals and fuels is a promising technology to use anthropogenic CO2 emissions for alleviating our dependence on fossil fuels. In this Primer, we provide a holistic step-by-step guide for the experimentation of photocatalytic CO2 reduction, including catalyst synthesis and characterization, reactor construction, photocatalytic testing and mechanism exploration. We compare and analyse the state-of-the-art results with different photocatalysts and discuss possible reaction mechanisms. Furthermore, important considerations regarding practical application of photocatalytic CO2 reduction are highlighted and strategies to enhance energy conversion efficiency and product selectivity are summarized. This Primer also reveals current issues of reproducibility, standardizes data reporting and proposes a unified operation condition. Finally, future directions are outlined in terms of experiments, calculations, big-data development and practical application
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