Isolation and phylogenetic analysis of zinc resistant Acinetobacter sp. and its potential for bioremediation

In this study, a gram negative, non- motile short rod-shaped and heavy metal resistant bacterial strain was isolated from effluents. The optimum temperature and pH for the growth of the strain were 33°C and 7, respectively. The minimum inhibitory concentrations (MICs) of zinc (Zn), copper (Cu), chromium (Cr) and mercury (Hg) against the isolate were determined. The isolate showed MICs of 5, 4, 3 and 2 mM when grown on Zn, Cu, Cr and Hg, respectively. The isolate was assessed for its ability to remove zinc from medium amended with different concentrations of zinc. Up to 65% of zinc was removed at the zinc concentration of 1 mM. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate belongs to the genus Acinetobacter with 98% similarity to Acinetobacter junni. It was then designated as Acinetobacter sp. HM_AF14. Based on the data obtained in this study, it can be concluded that Acinetobacter sp. HM_AF14 can be used for bioremediation of zinc from effluents.Keywords: Heavy metals, Acinetobacter sp., bioremediation, 16S rRNA, zinc removalAfrican Journal of Biotechnology Vol. 12(26), pp. 4123-412

The antibacterial effect of methanolic fraction of Nepeta depauperataon against Pseudomonas aeruginosa isolates from burn wound infections

Background: In this study, the antibacterial effect of the methanolic fraction of Nepeta depauperata against 50 isolates of Pseudomonas aeruginosa from burn wound infections of patients who referred to Shahid Motahari hospital of Tehran in 2014 was evaluated.Materials and Methods: All bacterial isolates were confirmed by standard bacteriologic methods. Their resistant to common antibiotics were evaluated by disk diffusion method based on CLSI 2014. The Nepeta depauperata aerial parts were collected from Hormozgan Province and identified. Methanolic extract was prepared by maceration method using percolator apparatus and concentrated by rotary evaporator. The antibacterial activity of methanolic extract were determined by two methods; cup plate diffusion agar for determination the zone diameter of inhibition and microdilution broth for minimum inhibitory concentration (MIC) and further minimum bacteriocidal concentration (MBC). Statistical analysis was done by SPSS software version 20.Results: The percentage of resistance and susceptibility against nine different kinds of common antibiotic disk showed 83% resistance on average as evaluated by agar disk diffusion (Kirby–Bauer antibiotic test). Also, the mean of inhibition zone diameters has been measured in concentrations of 1000, 500, 250 mg/ml as follow: 12.58, 11.3 and 9.44 mm, respectively by cup plate and the amount of 87.93 and 104.78 mg/ml for MIC and MBC were determined, respectively, using the broth microdilution method. Statistic analysis was done with SPSS verssion19 software.Conclusion: According to the satisfying results of the antibacterial effect of the testing methanolic extract against clinical isolates of P. aeruginosa isolates further in vitro and in vivo studies are recommended