Articles
World Journal of Microbiology and Biotechnology (09593993)40(5)
The aim of the current research was to improve violacein production with Janthinobacterium lividum using abiotic stresses and bacterial adaptation against stress. Initially, the effect of carbon sources and the medium volume: air ratio on violacein production was assessed. Then, the production of violacein under hydrogen peroxide (H2O2) and ampicillin (Amp) stresses and acyl homoserine lactone (AHL) was evaluated. In the next step, J. lividum was adapted against increased concentrations of Amp. Finally, the production of violacein was analyzed in adapted bacterium cultivated in the presence of optimal amounts of H2O2, Amp, and AHL. The alterations in the expression of some of genes involved in violacein production was evaluated using Real-time PCR (RT-PCR). The highest amount of violacein was achieved using medium volume: air ratio of 10% v/v (in 100 ml flasks) and glycerol as carbon source. Also, H2O2 (103 mg/l) and Amp (130 mg/l) stresses increased the production of violacein significantly compared to normal conditions (57 mg/l) and violacein production in the presence of crude AHL increased from 56 mg/l to 210 mg/l. The production of violacein with adapted bacterium under the above-mentioned stresses and AHL was about 1.3 g/l. RT-PCR results showed that the expression of the AHL encoding gene (luxI) was repressed in the presence of stresses and glycerol. Also, the expression of vioA increased in the presence of Amp but H2O2 had no significant effect on vioA expression. Totally, we showed that microbial adaptation and abiotic stresses are cost-effective methods to generate significant improvement in violacein production. © The Author(s), under exclusive licence to Springer Nature B.V. 2024.
Jalali dehkordi, M.,
Bahrami, A.,
Abbasi, M.S.,
Mokhtari, M.A.,
Heidari laybidi, F.,
Roosefid, A.,
Hosseini abari, A.,
Yazdan mehr, M. Coatings (20796412)14(12)
The increasidng demand for implants due to the aging populations highlights the necessity for applying highly functional coatings on the surface of implants. This study investigates the implications of applying a chitosan/polylysine composite coating on anodized titanium surfaces, aiming for improved biocompatibility, bioactivity, and anti-bacterial properties. Titanium substrates were anodized at 40 volts for a duration of two hours, followed by dip coating with the chitosan/polylysine composite. Fourier-transform infrared (FTIR) analysis was employed to characterize the polymer structure, while field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDS) techniques were utilized to evaluate nanotube morphology and the coating structure. Results showed that samples containing 1.5% polylysine exhibited noticeable anti-bacterial properties and cell viability above fifty percent. Subsequent immersion in simulated body fluid (SBF) for a duration of two weeks revealed the formation of apatite crystals on the coated samples, indicating that the samples are bioactive. Furthermore, polylysine contributed to enhanced resistance against degradation in phosphate-buffered saline (PBS) solution. Overall, the chitosan/polylysine composite coating exhibited promising mechanical and biomedical characteristics, suggesting its potential for applications in orthopedic implants. © 2024 by the authors.
Surfaces and Interfaces (24680230)45
The aim of this study was to develop multi-functional bioactive glass-based coatings with anti-cancer properties for biomedical applications. These coatings were specifically designed for AISI 316 stainless steel substrates. The surface was initially coated with a first layer comprising a composite of iron oxide nanoparticles and 45S5 bioactive glass, which was deposited on the surface through electrophoretic deposition. Subsequently, a second layer, consisting of Pectin and Pectic oligosaccharide polymers, was applied onto the base layer using the immersion technique. Various analytical techniques, including scanning electron microscope, X-ray diffraction, attenuated total reflectance fourier-transform infrared, energy-dispersive X-ray spectroscopy, vibrating sample magnetometry, specific loss power, and inductively coupled plasma, were employed to analyze the synthesized samples. In addition, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) tests, MCF-7 cell culture studies, and corrosion evaluations were also conducted. The vibrating sample magnetometry analyses revealed that the samples exhibited the highest saturation magnetization when synthesized using a Fe3O4 solution with a concentration of 0.5 g L−1. Specific Loss Power analysis indicated that a temperature of 42 °C could be attained within 175 s for the sample prepared under these conditions. The results demonstrated that all the coatings were found to possess hydrophilic surfaces. Examination of MCF-7 cell culture revealed that coatings with a pectic oligosaccharide top layer were found to exhibit remarkable cytotoxicity, leading to the destruction of up to 98.8 % of cancer cells within a two-hour exposure period at 48 °C. © 2024 Elsevier B.V.
