Concerns about health issues and environmental pollution stimulate research to find new health and hygiene related products with healing properties and minimum negative effect on the environment. Development of new, natural antibacterial agents has become one of the most important research areas to combat some pathogens such as Gram- positive and Gram-negative bacteria, fungi, algae, yeast, and some microorganisms which cause serious human infections. Lawsonia Inermis (henna) leaf extracts for preparation of antibacterial poly(ethylene oxide) (PEO) and poly(vinyl alcohol) (PVA) nanofibers via electrospinning technique were investigated. PEO and PVA based electrospun fibers containing henna extract were verified by the appearance of FTIR peaks corresponding to the pure extract. Our study demonstrates that 2.793 wt.% Li in PVA and PEO based solutions showed bactericidal effects against Staphylococcus aureus and bacteriostatic action to Escherichia coli. Concentrations of henna leaf extract strongly impacted antibacterial activities against both bacteria. Henna leaves have a great potential to be used as a source of a potent eco-friendly antimicrobial agent.

Melt spinning of polypropylene fibers containing silver and zinc nanoparticles was investigated. The nanometals were generally uniformly dispersed in polypropylene, but aggregation of these materials was observed on fiber surface and in fiber cross-sections. The mechanical properties of the resulted composite fibers with low concentration of nanometal were comparable to those for the control PP yarns. Extruded composite fibers that contained 0.72% silver and 0.60% zinc nanoparticles had outstanding antibacterial efficacy as documented by the percentage count reduction growth of Escherichia coli and Staphylococcus aureus. Fibers containing silver particles had improved antistatic properties.

To evaluate whether expression of cloned genes for the Fo proton channel of the Escherichia coli F1F0 ATPase is sufficient to cause membrane proton permeability, plasmids carrying different combinations of the uncB, E, and F genes, encoding the a, c, and b subunits of the Fo sector, cloned behind the inducible lac promoter in pUC9 or pUC18, were constructed. The effects of inducing Fo synthesis in an unc deletion strain were monitored by measuring cell growth rate, quantitating Fo subunits by immunoblotting, and measuring the ability of membranes to maintain a respiration-induced proton gradient and to bind F1 and carry out energy-coupling reactions. able form and then converted to its active, proton-conducting form by specific interactions with F1 subunits (18). As one test of this hypothesis, we constructed several plasmids carrying the genes for different Fo subunits cloned behind the inducible lac promoter and measured the effects of increasing amounts of Fo subunits on cell growth, membrane proton permeability, and the ability of membranes to bind purified F1 and carry out energy coupling reactions. The results support the model described above and also suggest that overexpression of Fo genes produces unassembled subunits that inhibit cell growth without necessarily affecting membrane proton permeability. MATERIALS AND METHODSStrains and plasmids. These studies were done in E. coli JM103 A(uncB-uncD), which is strain JM103 (13) in which seven of the nine unc genes (11), including all of the Fo genes, are deleted. Plasmid pEA4, which carries the three Fo genes in pACYC184, was described previously (2). Plasmid pEA5, which carries the three Fo genes cloned behind the inducible lac promoter, was constructed by cloning the HindIII-Sall fragment from pEA4 into pUC9 (25). Plasmid pRM2 was constructed by deleting the HpaI-SmaI fragment containing uncF from pEA5. Plasmid pRM2 was then digested with BamHI and religated to delete 617 bases from uncB, producing plasmid pRM3, which codes for the c subunit only. Plasmid pRM4 was constructed by cloning the HindIII-SalI fragment from pEA4 into pUC18. The resultant plasmid carries the same insert as pEA5, but the insert is in the opposite orientation to the lac promoter. When it is important for clarity, the subunits contained in each plasmid are given within parentheses after the plasmid designation.Growth and lac induction. Cells were grown in LB medium (14) containing 100 mg of ampicillin per liter, and growth was measured by monitoring cell turbidity (optical density at 550

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We studied the effect of the 8 subunit of the Escherichia coli F1 ATPase on the proton permeability of the Fo proton channel synthesized and assembled in vivo. Membranes isolated from an unc deletion strain carrying a plasmid containing the genes for the Fo subunits and the 8 subunit were significantly more permeable to protons than membranes isolated from the same strain carrying a plasmid containing the genes for the Fo subunits alone. This increased proton permeability could be blocked by treatment with either dicyclohexylcarbodiimide or purified Fl, both of which block proton conduction through the Fo. After reconstitution with purified F1 in vitro, both membrane preparations could couple proton pumping to ATP hydrolysis. These results demonstrate that an interaction between the 8 subunit and the Fo during synthesis and assembly produces a significant change in the proton permeability of the Fo proton channel. We have proposed a model for Fo assembly in which the Fo is synthesized and assembled in a relatively proton-impermeable form (3,15). Instead of the F1 subunits catalyzing membrane insertion of certain Fo subunits, the Fo subunits are inserted spontaneously and assemble in an immature form. It is through interactions with F1 subunits that this immature "closed" channel is opened, and the flow of protons through the complex is then regulated by the activity of the F1 sector. In this study, we examined the role of the 8 subunit of the F1 sector during assembly of the Fo sector. The 8 subunit is coded for by the uncH gene, which is the first F1 gene in the operon, located immediately following the Fo genes. Previous genetic studies implicated the 8 subunit as causing the F1-dependent proton permeability of the Fo (1 MATERIALS AND METHODSStrains and plasmids. These studies used E. coli JM103 A(uncB-uncD), which is strain JM103 (11) with a deletion of seven of the nine unc genes, including all the Fo genes (10).Plasmids pEA5, pWSB30.0, and pWSB33 were described previously (13, 22). pRM1, which carries the Fo genes plus uncH (S subunit) cloned behind the lac promoter, was constructed by digesting pWSB30.0 with HindIll and EcoRI and ligating the resulting fragments with the pUC9 (23) vector, which had been digested with HindIIl and EcoRI. pRM1 was digested with AflII, which cuts at the stop codon for uncH, treated with mung bean nuclease to form blunt ends, and then ligated with a Sall adapter (5'-TGGTGTCGACACCA-3') to produce plasmid pRM6. pRM7, which carries the Fo genes and all of uncH fused in frame to a biotinylation sequence, was constructed by ligating the SalI-EcoRI fragment from the biotinylation vector YEp352-Bio7 into pRM6, which had been digested with the same enzymes. YEp352-Bio7 was a generous gift from A. Tzagoloff. Treatment with mung bean nuclease and insertion of the Sall adapter removed the stop codon for uncH and allowed the biotin attachment sequence to be cloned in frame. This region of the resultant plasmid was sequenced to verify the construction. pRM8, which encodes the uncH-biotin a...