Expression and characterization of a chitinase from Serratia marcescens
Publication date: Available online 23 February 2020Source: Protein Expression and PurificationAuthor(s): Jincheng Li, Jiamin Zheng, Yanhui Liang, Renxiang Yan, Xinqi Xu, Juan LinAbstractA chitinase gene from Serratia marcescens was cloned and expressed in Escherichia coli and the properties of recombinant chitinase rCHI-2 were characterized. The optimum catalytic pH of rCHI-2 was 6.0. It was stable in the pH range of 6.0–9.0 and could maintain more than 90% of its relative enzyme activity after incubation at 37 °C for 1 h. The optimum catalytic temperature of the enzyme was 55 °C and 85% of enzyme activity was remained after incubation at 45 °C for 1 h. The activation energy of the thermal inactivation of the enzyme was 10.9 kJ/mol and the Michaelis-Menten constant was 3.2 g/L. The purified rCHI-2 was found to be highly stable at 45 °C with half-life (t1/2) of 289 min and thermodynamic parameters ΔH*, ΔG* and ΔS* revealed high affinity of rCHI-2 for chitin. Hg2+ was found to be able to inhibit the enzyme activity reversibly, while IC50 and inhibition constant of Hg2+ on the enzyme were 34.8 μmol/L and 44.6 μmol/L, respectively. Moreover, rCHI-2 could specifically hydrolyze colloidal chitin into GlcNAc2 as the major product.
In conclusion, this study confirmed for the first time the presence of E. coli carried carbapenem-resistant genes in the drinking water of Khartoum state, Sudan. These isolates commonly carried OXA-48 (7/45), followed by SPM (4/45) and KPC (2/45). PMID: 32612664 [PubMed - in process]
Publication date: Available online 3 July 2020Source: Food ControlAuthor(s): Madeleine Moazzami, Lise-Lotte Fernström, Ingrid Hansson
In this study, a series of new 4-hydroxy-2-quinolinone analogs containing a long alkyl side chain at C-3 and a broad range of substituents on the C-6 and C-7 positions were synthesized. The antibacterial and antifungal activities of these analogs against Staphylococcus aureus, Escherichia coli, and Aspergillus flavus were investigated. The structure-activity relationship study revealed that the length of the alkyl chain, as well as the type of substituent, has a dramatic impact on the antimicrobial activities. Particularly, the brominated analogs 3j with a nonyl side chain exhibited exceptional antifungal activities agains...
Publication date: September 2020Source: LWT, Volume 131Author(s): Maomao Ma, Junxin Zhao, Zheling Zeng, Dongman Wan, Ping Yu, Ding Cheng, Deming Gong, Shuguang Deng
In conclusion, observations from the study implied that most water sources in the study district are highly polluted with bacteria pathogens beyond recommended safety guidelines. The main causes of faecal contamination in these water sources were purported to be anthropogenic. Therefore, there is a need to formulate a policy aimed at managing and improving rural water sources. PMID: 32612658 [PubMed]
Conclusion: Considering the high prevalence of UTI and antibiotic resistance rates in kidney transplant patients in our study, there is an urgent need for developing hospital based local antibiogram for appropriate management of UTI. Fosfomycin as an empirical therapy might be a useful choice for adequate coverage of potential pathogens at our centre. Further multi-centric studies on a larger sample size are recommended from India for formulating antibiotic policy. PMID: 32610862 [PubMed - in process]
Publication date: Available online 2 July 2020Source: Journal of Global Antimicrobial ResistanceAuthor(s): João Pedro Rueda Furlan, Irys Hany Lima Gonzalez, Patrícia Locosque Ramos, Eliana Guedes Stehling
A. S. Saidenberg et al.
Background: Localized delivery of antimicrobial agents such as antimicrobial peptides (AMPs) by a biomaterial should be on-demand. Namely, AMPs should be latent and biocompatible in the absence of bacterial infection, but released in an amount enough to kill bacteria immediately in response to bacterial infection.Methods: To achieve the unmet goal of such on-demand delivery, here we turned a titanium implant with titania nanotubes (Ti-NTs) into a Pandora's box. The box was loaded with AMPs (HHC36 peptides, with a sequence of KRWWKWWRR) inside the nanotubes and “closed” (surface-modified) with a pH-responsive mo...
Conclusions: This novel peptide MSI-1 could be a potential candidate for drug development against infection induced by drug-resistant bacteria.