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The design of actively efficient and low-toxicity formulations against virulent bacterial strains causing skin infections remains a challenging task. The aim of the present study was to develop and evaluate in vitro a hydrogel impregnated with a known plant extract for topical applications against major skin bacteria. A poly(vinyl alcohol) (PVA)/gelatin hydrogel, namely HG, was prepared by esterification following the solution casting method. The gelling process was realized by cross-linking the synthetic polymer PVA and the biopolymer gelatin in the presence of hydrochloric acid (HCl). A crude extract of Nigella sativa seeds was then encapsulated in HG, and the resulting HGE was characterized morphologically (by Scanning Electron Microscopy (SEM)), structurally (by X-ray powder diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy), behaviorally (by swelling behavior), and biologically (by the agar well diffusion method). The results of HGE were compared to HG and HG impregnated with 10% acetic acid (HGAA). SEM sections of HGE revealed a dense and porous surface, suggesting a good hydrophilicity. X-ray diffractograms indicated that HGE and HG had a similar degree of crystallinity. FTIR spectra confirmed that esterification occurred between PVA and gelatin suggesting that the amine group is involved in the intercalation of the plant extract components in HG. Further, HGE was found to be as wettable and swellable as HG, suggesting a good biocompatibility. Eventually, HGE exerted a pronounced inhibitory effect against two major skin pathogens, the Gram-negative Pseudomonas aeruginosa and the Gram-positive Staphylococcus aureus, suggesting a good extract release. Taken together, the experimental data indicated that HGE might be a promising wound dressing.

The use of microbial technologies in agriculture is currently expanding quite rapidly with the identification of new bacterial strains, which are more effective in promoting plant growth. In the present study 18 strains of Pseudomonas were isolated from soil sample of Balochistan coastline. Among isolated Pseudomonas strains four designated as SP19, SP22, PS24, and SP25 exhibited biocontrol activities against phytopathogenic fungi, that is, Rhizopus microsporus, Fusarium oxysporum, Aspergillus niger, Alternaria alternata, and Penicillium digitatum; PS24 identified as Pseudomonas aeruginosa by 16srRNA gene bank accession number EU081518 was selected on the basis of its antifungal activity to explore its potential as plant growth promotion. PS24 showed multiple plant growth promoting attributes such as phosphate solubilization activity, indole acetic acid (IAA), siderophore, and HCN production. In order to determine the basis for antifungal properties, antibiotics were extracted from King B broth of PS24 and analyzed by TLC. Pyrrolnitrin antibiotic was detected in the culture of strain PS24. PS24 exhibited antifungal activities found to be positive for hydrogen cyanide synthase Hcn BC gene. Sequencing of gene of Hcn BC gene of strain PS24 revealed 99% homology with the Pseudomonas aeruginosa strain PA01. The sequence of PS24 had been submitted in gene bank accession number KR605499. Ps. aeruginosa PS24 with its multifunctional biocontrol possessions can be used to bioprotect the crop plants from phytopathogens.