Pseudobactins bounded iron nanoparticles for control of an antibiotic-resistant Pseudomonas aeruginosa ryn32

Leveraging bacteria-inspired nanomaterials for targeted controlling biofilm and virulence properties of Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic pathogen designated as a high-priority pathogen because of its role in major healthcare-associated and nosocomial infections. Biofilm production by these bacteria is one of the adaptive resistance mechanisms to traditional antibiotics, making treatment challenging, especially for immunocompromised patients. P. aeruginosa also produces a variety of virulence factors, which aid in invasion, adhesion, persistence, and immune system protection. Recent advances in nanotechnology-based therapy, notably the application of bioinspired metal and metal-oxide nanomaterials, have been seen as a viable way to control P. aeruginosa biofilm and virulence. Because of its ease of growth and culture, synthesizing metal and metal-oxide nanomaterials using bacterial species has become one of the most environmentally benign green synthesis options. The application of bacterial-inspired nanomaterials is particularly successful for targeted control of P. aeruginosa infection due to interactions with cell membrane components and transport systems. This paper delves into and provides a complete overview of the application of bacterial-inspired metal and metal-oxide nanomaterials to treat P. aeruginosa infection by targeting biofilm and virulence characteristics. The review focused on synthesizing and applying gold, silver, copper, iron, magnetite, and zinc oxide nanomaterials to mitigate P. aeruginosa biofilm and virulence. The underlying mechanism of these metal and metal-oxide nanoparticles in relation to biofilm and virulence features has also been thoroughly discussed. The current review introduces novel approaches to treating and controlling drug-resistant P. aeruginosa using bacterial-inspired nanomaterials as a targeted therapeutic strategy.

Production and Antibacterial Activity of Atypical Siderophore from Pseudomonas sp. QCS59 Recovered from Harpachene schimperi

Among sixty-eight pseudomonads, isolate QCS59 from the rhizosphere of H. schimperi was selected based on its siderophore level. Production was optimal in Kings B supplemented with 2% peptone and 0.5% fructose at pH 6.5 and 25 °C for 72 h. Additionally, the threshold potential of iron was found at a concentration of 10 µM. After purification, the acidified siderophore presented a maximum absorption peak of 360 nm, while the neutral form presented a maximum of 414 nm, confirming its pyoverdine (PVD) nature. Furthermore, a major peak appeared at a retention time (RT) of 27.5 min during RP-HPLC, confirming its homogeneity. Interestingly, it demonstrated effective antibacterial activity, especially against Escherichia coli ATCC 8739, with a minimum inhibitory concentration (MIC) of 6.3 µg/mL and a minimum bactericidal concentration (MBC) of 12.5 µg/mL. At ½ the MIC value, it inhibited 82.1% of well-established biofilms of Salmonella enterica. There was an increase in malondialdehyde (MDA) and antioxidative enzymes, especially catalase (CAT) in the treated bacteria because of the peroxidation of membrane lipids and oxidative stress, respectively. SEM proved cellular lysis and surface malformation in most of the treated bacteria. This study concludes that QCS59 siderophore is a promising antibacterial candidate for treating wastewater bacteria and skin pathogens.

Anticandidal Activity of a Siderophore from Marine Endophyte Pseudomonas aeruginosa Mgrv7

An endophytic symbiont P. aeruginosa-producing anticandidal siderophore was recovered from mangrove leaves for the first time. Production was optimal in a succinate medium supplemented with 0.4% citric acid and 15 µM iron at pH 7 and 35 °C after 60 h of fermentation. UV spectra of the acidic preparation after purification with Amberlite XAD-4 resin gave a peak at 400 nm, while the neutralized form gave a peak at 360 nm. A prominent peak with RP-HPLC was obtained at RT 18.95 min, confirming its homogeneity. It was pH stable at 5.0-9.5 and thermally stable at elevated temperatures, which encourages the possibility of its application in extreme environments. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) against Candida spp. Were in the range of 128 µg/mL and lower. It enhanced the intracellular iron accumulation with 3.2-4.2-fold (as judged by atomic absorption spectrometry) with a subsequent increase in the intracellular antioxidative enzymes SOD and CAT. Furthermore, the malondialdehyde (MDA) concentration due to cellular lipid peroxidation increased to 3.8-fold and 7.3-fold in C. albicans and C. tropicalis, respectively. The scanning electron microscope (SEM) confirmed cellular damage in the form of roughness, malformation, and production of defensive exopolysaccharides and/or proteins after exposure to siderophore. In conclusion, this anticandidal siderophore may be a promising biocontrol, nonpolluting agent against waterborne pathogens and pathogens of the skin. It indirectly kills Candida spp. by ferroptosis and mediation of hyperaccumulation of iron rather than directly attacking the cell targets, which triggers the activation of antioxidative enzymes.

Pseudomonas aeruginosa virulence attenuation by inhibiting siderophore functions

Pseudmonas aeruginosa is a Gram-negative bacterium known to be ubiquitous and recognized as one of the leading causes of infections such as respiratory, urinary tract, burns, cystic fibrosis, and in immunocompromised individuals. Failure of antimicrobial therapy has been documented to be attributable due to the development of various resistance mechanisms, with a proclivity to develop additional resistance mechanisms rapidly. P. aeruginosa virulence attenuation is an alternate technique for disrupting pathogenesis without impacting growth. The iron-scavenging siderophores (pyoverdine and pyochelin) generated by P. aeruginosa have various properties like scavenging iron, biofilm formation, quorum sensing, increasing virulence, and toxicity to the host. As a result, developing an antivirulence strategy, specifically inhibiting the P. aeruginosa siderophore, has been a promising therapeutic option to limit their infection. Several natural, synthetic compounds and nanoparticles have been identified as potent inhibitors of siderophore production/biosynthesis, function, and transport system. The current review discussed pyoverdine and pyochelin's synthesis and transport system in P. aeruginosa. Furthermore, it is also focused on the role of several natural and synthetic compounds in reducing P. aeruginosa virulence by inhibiting siderophore synthesis, function, and transport. The underlying mechanism involved in inhibiting the siderophore by natural and synthetic compounds has also been explained. KEY POINTS: • Pseudomonas aeruginosa is an opportunistic pathogen linked to chronic respiratory, urinary tract, and burns infections, as well as cystic fibrosis and immunocompromised patients. • P. aeruginosa produces two virulent siderophores forms: pyoverdine and pyochelin, which help it to survive in iron-deficient environments. • The inhibition of siderophore production, transport, and activity using natural and synthesized drugs has been described as a potential strategy for controlling P. aeruginosa infection.

Potent antibacterial activity of MXene-functionalized graphene nanocomposites

Two dimensional (2D) nanomaterials display properties with significant biological utility (e.g., antimicrobial activity). In this study, MXene-functionalized graphene (FG) nanocomposites with Ti3C2T x in varying ratios (FG : Ti3C2T x , 25 : 75%, 50 : 50%, and 75 : 25%) were prepared and characterized via scanning electron microscopy, scanning electron microscopy-energy dispersive X-ray (SEM-EDX), high-resolution transmission electron microscopy (HRTEM), and zeta potential analysis. Their cytotoxicity was assessed using immortalized human keratinocytes (HaCaT) cells at three different timepoints, and antibacterial activity was assessed using Gram-positive Methicillin resistant Staphylococcus aureus, MRSA, and Gram-negative neuro-pathogenic Escherichia coli K1 (E. coli K1) in vitro. The nanomaterials and composites displayed potent antibacterial effects against both types of bacteria and low cytotoxicity against HaCaT cells at 200 μg mL-1, which is promising for their utilization for biomedical applications.

Synthesis and characterization of chitosan encapsulated zinc oxide (ZnO) nanocomposite and its biological assessment in pepper (Capsicum annuum) as an elicitor for in vitro tissue culture applications

Nanotechnology paves the way for introducing nanoscale fertilizers, pesticides, and elicitors. This study intends to address the synthesis of chitosan/zinc oxide nanocomposite (CS-ZnONP) and its biological assessment in in-vitro conditions. The zinc oxide nanoparticles (ZnONPs) were successfully coated with the chitosan (CS) polymer through a cost-effective approach. Transmission electron microscopy and Fourier transform infrared spectroscopy assessments proved the surface capping of chitosan polymer on ZnONP. The nanocomposite was more capable of improving growth and biomass than the bare ZnONPs. The application of the nanocomposite increased the concentration of chlorophylls (51%), carotenoids (70%), proline (2-fold), and proteins (about 2-fold). The supplementation of culture medium with the nanomaterials upregulated enzymatic antioxidant biomarkers (catalase and peroxidase). The activity of the phenylalanine ammonia-lyase enzyme also displayed a similar significant upward trend in response to the nano-supplements. The CS-ZnONP treatment considerably enhanced the accumulation of alkaloids (60.5%) and soluble phenols (40%), implying stimulation in secondary metabolism. The micropropagation test revealed that the CS-ZnONP treatment improved the organogenesis performance. Overall, the nanocomposite can be considered a highly potent biocompatible elicitor.

UV-enhanced nano-nickel ferrite-activated peroxymonosulfate for the degradation of chlortetracycline hydrochloride in aqueous solution

In this study, nano-nickel ferrite (NiFe2O4) was successfully prepared by hydrothermal synthesis and applied to the oxidative removal of chlortetracycline hydrochloride (CTH) in the presence of ultraviolet radiation (UV) and peroxymonosulfate (PMS). Several characterization methods were used to reveal the morphology and surface properties of nano-NiFe2O4, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared absorption (FTIR) spectroscopy. The removal efficiency of CTH, the factors affecting the reaction process and the reaction mechanism of PMS activated by UV combined with nano-NiFe2O4 (UV + nano-NiFe2O4/PMS) in aqueous solution were systematically studied. The results showed that the UV + nano-NiFe2O4/PMS system led to a higher removal efficiency of CTH than other parallel systems. The results also showed that the CTH removal efficiency was enhanced under optimal conditions ([nano-NiFe2O4] = 1 g L-1, [PMS] = 1 g L-1, [UV wavelength] = 254 nm and [pH] = 11) and that a removal efficiency of 96.98% could be achieved after 60 min. In addition, the influence of the PMS concentration, CTH concentration, dosage of added nano-NiFe2O4 and pH on the PMS activation efficiency and CTH oxidative degradation effect was studied. Inorganic anions such as Cl-, HCO3 -, CO3 2- and NO3 - increased the removal efficiency of CTH by 21.29%, 27.17%, 25.32% and 5.96% respectively, while H2PO4 - inhibited CTH removal, and the removal efficiency of CTH decreased 6.08% after 60 min. Free radical identification tests detected SO4 -˙, OH˙ and 1O2 and showed that these species participated in the degradation reaction of CTH. The results of LC-MS and TOC analysis showed that CTH was degraded in the UV + nano-NiFe2O4/PMS system through hydroxylation, demethylation, deamination, and dehydration reaction and finally mineralized into CO2. These findings confirmed that nano-NiFe2O4 is a green and efficient heterogeneous catalyst for activation of PMS and demonstrates potential applicability in the treatment of antibiotic wastewater.

Zinc oxide nanoparticles decorated fluorescent and antibacterial glass fiber pre-filter paper

Zinc oxide nanoparticles (ZnO–NPs) were synthesized and decorated simultaneously onto the glass fiber pre-filter paper (GF paper) by the sonochemical method without using any additional reagents (a ‘Green’ synthesis approach). ZnO–NPs decorated GF paper was characterized by electron, confocal laser scanning and atomic force microscopy, fourier transform infrared and atomic emission spectroscopy, X-ray diffraction, and thermogravimetric analysis etc. Due to the massive void volume space, exceptional dimensional stability, large thickness (790 μm) of the GF paper (unlike other paper materials) and ultrasonic irradiation effects, ZnO–NPs were decorated in the enormous amount (96 mg per paper) without causing any adverse effects on the GF paper. Such a huge amount decoration onto GF paper makes it multifunctional, fluorescencet (orange-pink color, 535–624 nm) under ultra-violet light (360 nm) and antibacterial. The antibacterial activity of the ZnO–NPs decorated GF paper was examined against Gram-positive bacteria Bacillus subtilis 168 and Staphylococcus aureus (MCC 2043, pathogenic). The outcomes from the antibacterial experiments revealed ∼99% (2 log) reduction in the survival of the filtered bacteria (B. subtilis) on the ZnO–NPs decorated GF paper due to the toxicity of ZnO–NPs on bacterial cells like cell shrinkage, cytoplasmic leakage, cell burst, etc. Multifunctional, ZnO–NPs decorated GF paper could be used for fluorescencet and antibacterial paper-based applications.