Herein, a galactan exopolysaccharide (EPS) producing marine bacteria Vibrio Sp. BPM19 was reported. Phylogenetic analysis based on 16S rRNA gene sequencing showed the proximity of the isolate to Vibrio alginolyticus strain 1306. Gel permeation chromatography revealed the molecular weight of the purified EPS was about 6342.3 Daltons. 1H NMR, 13C NMR, and FTIR analysis indicated that isolated EPS comprises high molecular weight polysaccharides. HPLC analysis suggests that the EPS is composed of a repeating unit of galactose. DSC-TGA studies support that the EPS has very high thermal stability. The potential application of purified EPS in nanotechnology was demonstrated by the synthesis of platinum nanocomposite (PtNC). The PtNC was characterized by energy-dispersive X-ray diffraction, transmission electron microscopy, zeta potential, particle size analysis, and FTIR. The antimicrobial potential of the PtNC was demonstrated against drug-resistance Salmonellae typhi and Staphylococcus aureus. The result suggested the possible commercial scope of the isolated strain to produce galactan, which can synthesize antimicrobial metal nanocomposite. 

Isolation of exopolysaccharide, galactan from marine Vibrio sp. BPM 19 to template the synthesis of antimicrobial platinum nanocomposite

Targeted drug delivery maximizes the chance to combat infection caused by drug-resistant pathogens. Herein, lectin-fortified cationic copper sulfide (cCuS) nanoparticles were suggested for targeted adhesion to bacterial membranes and to enforce bacterial death. Jacalin, a lectin from jackfruit seed, was conjugated to fluorescein isothiocyanate (FITC), and its ability to recognize bacterial cell surface glycans was demonstrated. Jacalin formed a noncovalent complex with cCuS, which was investigated by fluorescence quenching measurements. The data revealed that jacalin–cCuS (JcCuS) had a good affinity with an association constant Ka of 2.27 (± 0.28) × 104 M–1. The resultant JcCuS complex displayed excellent anti-infective activity against carbapenem-resistant Acinetobacter baumannii (CRAB). The minimum inhibitory concentration (MIC) of cCuS was 62.5 μM, which was 2-fold lower than that of the broad-spectrum antibiotic ciprofloxacin. Interestingly, the MIC of JcCuS was reduced to 15.63 μM, which was attributed to jacalin fortification. The mechanistic study unveiled that JcCuS affected the membrane integrity, depolarized the inner membrane, and produced excess reactive oxygen species to combat CRAB at a lower concentration compared to cCuS. A. baumannii formed a biofilm more readily, which played a critical role in pathogenesis and resistance in clinical settings. JcCuS (3.91 μM) displayed stronger antibiofilm activity without affecting the metabolic viability of CRAB. Microscopy analyses confirmed the inhibition of biofilm formation and disruption of the mature biofilm upon treatment with JcCuS. Furthermore, JcCuS hindered pellicle formation and inhibited the biofilm-associated virulence factor of CRAB such as exopolysaccharide, cell surface hydrophobicity, swarming, and twitching mobility. The anti-infective potential of JcCuS was demonstrated by rescuing CRAB-infected zebrafish. The reduction in pathogen proliferation in muscle tissues was observed in the treated group, and the fish recovered from the infection and was restored to normal life within 12 h. The findings illustrate that lectin fortification offers a unique advantage in enhancing the therapeutic potential of antimicrobials against human pathogens of critical priority worldwide.

https://pubs.acs.org/doi/pdf/10.1021/acsomega.2c05252

Lectin-Fortified Cationic Copper Sulfide Nanoparticles Gain Dual Targeting Capabilities to Treat Carbapenem-Resistant Acinetobacter baumannii Infection

Copper is a metal historically used to prevent infections. One of the most relevant challenges in modern society are infectious disease outbreaks, where copper-based technologies can play a significant role. Currently, copper nanoparticles and surfaces are the most common antimicrobial copper-based technologies. Despite the widespread use of copper on nanoparticles and surfaces, the toxicity mechanism(s) explaining their unique antimicrobial properties are not entirely known. In general, toxicity effects described in bacteria and fungi involve the rupture of membranes, accumulation of ions inside the cell, protein inactivation, and DNA damage. A few studies have associated Cu-toxicity with ROS production and genetic material degradation in viruses. Therefore, understanding the mechanisms of the toxicity of copper nanoparticles and surfaces will contribute to developing and implementing efficient antimicrobial technologies to combat old and new infectious agents that can lead to disease outbreaks such as COVID-19. This review summarizes the current knowledge regarding the microbial toxicity of copper nanoparticles and surfaces and the gaps in this knowledge. In addition, we discuss potential applications derived from discovering new elements of copper toxicity, such as using different molecules or modifications to potentiate toxicity or antimicrobial specificity.

/pdf/toxicity-mechanisms-of-copper-nanoparticles-and-copper-1lnibl49.pdf

Toxicity Mechanisms of Copper Nanoparticles and Copper Surfaces on Bacterial Cells and Viruses

Gram-negative bacterial (GNB) infections represent a worldwide serious public health challenge, especially with the increased global spread of carbapenem resistance (CR) among these pathogens. There are different forms of CR including, intrinsic and acquired mechanisms, one of the most significant of which is carbapenemase production. In the last decade, the widespread plasmid-mediated carbapenemase production, on top of the chromosomally encoded carbapenemasesalready abundant since the 1990sfurther complicated the situation and necessitated urgent intervention to further understand and tackle this issue. In this review, the phenotypic and genotypic methods for the detection of different types of carbapenemase have been discussed. Also, the different control measures and strategies that should be applied in an attempt to control the massive spread of GNB infections especially in healthcare facilities, have been elaborated on in this article. The challenges of GNB-associated infection in terms of the emergence of resistance to carbapenems, the last line of defense against GNB, and the continuing spread of this resistance left us with almost no options for treatment as well as their complication on the host. On the other hand, we explore the various opportunities for their control such as the development of new classes of antimicrobials and the structural modification of existing ones. It is also inevitable to explore novel treatment options including the association of antimicrobial agents with non-antimicrobials, inhibition of quorum sensing, bacteriophage therapy, photodynamic therapy, and monoclonal antibodies for treatment and prevention.

/pdf/new-insights-on-the-carbapenem-resistant-gram-negative-3arobt1o.pdf

M P Tharunya

Papers

Antimicrobial lipid capped copper sulfide nanoparticles display enhanced bactericidal effect against Carbapenem-Resistant Acinetobacter baumannii