Poly-Gamma-Glutamic Acid Nanopolymer Effect against Bacterial Biofilms: In Vitro and In Vivo Study.

In this study, a biodegradable poly-gamma-glutamic-acid nanopolymer (Ɣ-PGA NP) was investigated for its activity against clinical strains of Gram-positive (Staphylococcus aureus and Streptococcus pyogenes) and Gram-negative (Klebsiella pneumoniae and Escherichia coli), and reference strains of S. aureus ATCC 6538, S. pyogenes ATCC 19615 (Gram-positive), and Gram-negative E. coli ATCC 25922, and K. pneumoniae ATCC 13884 bacterial biofilms. The minimum inhibitory concentration (MIC) effect of Ɣ-PGA NP showed inhibitory effects of 0.2, 0.4, 1.6, and 3.2 µg/mL for S. pyogenes, S. aureus, E. coli, and K. pneumoniae, respectively. Also, MIC values were 1.6, 0.8, 0.2, and 0.2 µg/mL for K. pneumoniae ATCC 13884, E. coli ATCC 25922, S. aureus ATCC 6538, and S. pyogenes ATCC 19615, respectively. Afterwards, MBEC (minimum biofilm eradication concentration) and MBIC (minimum biofilm inhibitory concentration) were investigated to detect Ɣ-PGA NPs efficiency against the biofilms. MBEC and MBIC increased with increasing Ɣ-PGA NPs concentration or time of exposure. Interestingly, MBIC values were at lower concentrations of Ɣ-PGA NPs than those of MBEC. Moreover, MBEC values showed that K. pneumoniae was more resistant to Ɣ-PGA NPs than E. coli, S. aureus, and S. pyogenes, and the same pattern was observed in the reference strains. The most effective results for MBEC were after 48 h, which were 1.6, 0.8, 0.4, and 0.2 µg/mL for K. pneumoniae, E. coli, S. aureus, and S. pyogenes, respectively. Moreover, MBIC results were the most impactful after 24 h but some were the same after 48 h. MBIC values after 48 h were 0.2, 0.2, 0.2, and 0.1 µg/mL for K. pneumoniae, E. coli, S. aureus, and S. pyogenes, respectively. The most effective results for MBEC were after 24 h, which were 1.6, 0.8, 0.4, and 0.4 µg/mL for K. pneumoniae ATCC 13884, E. coli ATCC 25922, S. aureus ATCC 6538, and S. pyogenes ATCC 19615, respectively. Also, MBIC results were the most impactful after an exposure time of 12 h. MBIC values after exposure time of 12 h were 0.4, 0.4, 0.2, and 0.2 µg/mL for K. pneumoniae ATCC 13884, E. coli ATCC 25922, S. aureus ATCC 6538, and S. pyogenes ATCC 19615, respectively. Besides that, results were confirmed using confocal laser scanning microscopy (CLSM), which showed a decrease in the number of living cells to 80% and 60% for MBEC and MBIC, respectively, for all the clinical bacterial strains. Moreover, living bacterial cells decreased to 70% at MBEC while decreasing up to 50% at MBIC with all bacterial refence strains. These data justify the CFU quantification. After that, ImageJ software was used to count the attached cells after incubating with the NPs, which proved the variation in live cell count between the manual counting and image analysis methods. Also, a scanning electron microscope (SEM) was used to detect the biofilm architecture after incubation with the Ɣ-PGA NP. In in vivo wound healing experiments, treated wounds of mice showed faster healing (p < 0.00001) than both the untreated mice and those that were only wounded, as the bacterial count was eradicated. Briefly, the infected mice were treated faster (p < 0.0001) when infected with S. pyogenes > S. aureus > E. coli > K. pneumoniae. The same pattern was observed for mice infected with the reference strains. Wound lengths after 2 h showed slightly healing (p < 0.001) for the clinical strains, while treatment became more obvious after 72 h > 48 h > 24 h (p < 0.0001) as wounds began to heal after 24 h up to 72 h. For reference strains, wound lengths after 2 h started to heal up to 72 h.

Effect of the Morphology of Tungsten Oxide Embedded in Sodium Alginate/Polyvinylpyrrolidone Composite Beads on the Photocatalytic Degradation of Methylene Blue Dye Solution.

Tungsten oxide nanostructures were modified by oxygen vacancies through hydrothermal treatment. Both the crystalline structure and morphological appearance were completely changed. Spherical WO3·H2O was prepared from tungstic acid solution by aging at room temperature, while rod-like WO3·0.33H2O was prepared by hydrothermal treatment of tungstic acid solution at 120 °C. These structures embedded in sodium alginate (SA)/polyvinylpyrrolidone (PVP) were synthesized as novel porous beads by gelation method into calcium chloride solution. The performance of the prepared materials as photocatalysts is examined for methylene blue (MB) degradation in aqueous solutions. Different operation parameters affecting the dye degradation process, such as light intensity, illumination time, and photocatalyst dosage are investigated. Results revealed that the photocatalytic activity of novel nanocomposite changed with the change in WO3 morphology. Namely, the beads with rod nanostructure of WO3 have shown better effectiveness in MB removal than the beads containing WO3 in spherical form. The maximum degradation efficiency was found to be 98% for WO3 nanorods structure embedded beads, while the maximum removal of WO3 nanospheres structure embedded beads was 91%. The cycling-ability and reuse results recommend both prepared structures to be used as effective tools for treating MB dye-contaminated wastewaters. The results show that the novel SA/PVP/WO3 nanocomposite beads are eco-friendly nanocomposite materials that can be applied as photocatalysts for the degradation of cationic dyes in contaminated water.

Fate and transport of monensin in the presence of nonionic surfactant Brij35 in soil.

As fresh water is a limited resource in many parts of the world, the use of wastewater for irrigation has become an important alternative. Therefore, many countries facing a water deficit, use partially treated, or even untreated, wastewater. This may increase the input of many contaminants into the environment. In the present study, we investigated the effect of using surfactant rich water in irrigation on the mobility of the most commonly-used veterinary antibiotic, monensin. Nine PVC lysimeters, 1.0m long×0.45 m diameter, were packed with a sandy soil to a bulk density of 1.35 Mg m(-3). Cattle manure, containing monensin, was applied at the surface of the lysimeters at the recommended rate of 10t/ha. Each of three aqueous Brij 35 solutions, 0, 0.5 and 5 g L(-1), was applied to the lysimeters in triplicate. Over a 90 day period, soil and leachate samples were collected and analyzed. The results of the laboratory sorption experiment showed that when the nonionic surfactant Brij 35 is present, the sorption coefficient of monensin was reduced significantly from 120.22 mL g(-1) in the aqueous medium to 112.20, 100 and 63.09 mL g(-1) with Brij35 concentrations of 0.25, 2.5 and 5 g L(-1), respectively. The lysimeter results indicated a significant downward movement of monensin at depths of 60 cm in the soil profile and leachate in the presence of the surfactant. Thus, the continuous use of poor quality water could influence the transport of monensin in agricultural soils, and consequently, pose a risk for groundwater pollution.

Sorption/desorption behavior of oxytetracycline and sulfachloropyridazine in the soil water surfactant system.

Sorption/desorption of antibiotics, oxytetracycline (OTC), and sulfachloropyridazine (SCP) was investigated in the presence of a nonionic surfactant Brij35. Batch sorption experiments indicated that Freundlich equation fits sorption isotherms well for OTC. The sorption coefficients, KF, values were computed as 23.55 mL g(−1) in the absence of Brij35 and 25.46 mL g(−1) in the presence of Brij35 in the monomer form (below critical micelle concentration CMC, of 74 mg L(−1)). However, the KF values reduced to 12.76 mL g(−1) in the presence of Brij35 at 2.5 g L(−1). Therefore, irrigation with surfactant-rich water may increase the leaching potential of OTC. In the case of SCP, the KF value, in the absence of Brij35, was 19.95 mL g(−1). As a result of increasing the concentration of Brij35 to 0.25 g L(−1) (about 2.5 CMC), KF values first increased and reached a maximum value of 95.49 mL g(−1) and then reduced to 66.06 mL g(−1), at surfactant concentration of 5 g L(−1). Unlike OTC, the presence of surfactant in irrigation water is likely to decrease SCP leaching. In the case of OTC, hysteresis was found at Brij35 concentrations below CMC. However, OTC desorbed readily from soil (no hysteresis) at Brij35 concentrations above CMC. In the case of SCP, no hysteresis was found in the presence of the surfactant, both below and above CMC. Further, the obtained values of the efficiency coefficient (E), reveals that Brij35 had the potential to release more OTC from the soil (E > 1) as compared to SCP (E < 1). From these results, it can be concluded that regular use of manure on agricultural soils, especially in regions where poor quality irrigation water is used, can increase OTC contamination of water resources.

Effect of nonionic surfactant Brij 35 on the fate and transport of oxytetracycline antibiotic in soil.

In many parts of the world, river water is used for irrigation. Treated, partially treated, and even untreated water from wastewater treatment plants is discharged directly into rivers, thereby degrading the quality of the water. Consequently, irrigation water may contain surfactants which may affect the fate and transport of chemicals such as pesticides and antibiotics in agricultural soils. A field lysimeter study was undertaken to investigate the effect of the nonionic surfactant, Brij 35, on the fate and transport of an antibiotic, Oxytetracycline, commonly used in cattle farms. Nine PVC lysimeters, 1.0 m long × 0.45 m diameter, were packed with a sandy soil to a bulk density of 1.35 Mg m(-3). Cattle manure, containing Oxytetracycline, was applied at the surface of the lysimeters at the recommended rate of 10 t/ha. Each of three aqueous Brij 35 solutions, 0, 0.5 and 5 g L(-1) (i.e., 'good,' 'poor' and 'very poor' quality irrigation water) were each applied to the lysimeters in triplicate. Over a 90 day period, soil and leachate samples were collected and analyzed. Batch experiment results showed that the presence of the nonionic surfactant Brij 35 significantly reduced the sorption coefficient of OTC from 23.55 mL g(-1) in the aqueous medium to 19.49, 12.49 and 14.53 in the presence of Brij 35 at concentrations of 0.25, 2.5 and 5 g L(-1), respectively. Lysimeter results indicted the significant downward movement of OTC at depths of 60 cm into soil profile and leachate in the presence of surfactant. Thus, the reuse of wastewater containing surfactants might enhance the mobility of contaminants and increase ground water pollution.