Tehran University of Medical Sciences
Iranian Journal of Microbiology
2008-3289
7
2
2015
10
13
High potential application in bioremediation of selenate by Proteus hauseri strain QW4
94
102
EN
Mohaddeseh
Khalilian
Department of Microbiology, Faculty of Basic Sciences, Qom Branch, Islamic Azad University, Qom, Iran.
Mohammad Reza
Zolfaghari
Department of Microbiology, Faculty of Basic Sciences, Qom Branch, Islamic Azad University, Qom, Iran.
Mohammad
Soleimani
Department of Microbiology, Faculty of Basic Sciences, Qom Branch, Islamic Azad University, Qom, Iran.
2015
10
12
2015
10
12
Background and Objective: Selenium is essential for biological systems at low concentrations and toxic at higher levels. Heavy metals and metalloids such as selenium are major contaminants in 40% of hazardous waste sites. Thus, bioremediation has been considered as an effective means of cleaning up of selenium-contaminated sites.
Materials and Methods: In this study, 30 strains were isolated from wastewater samples collected from seleniumcontaminated sites in Qom, Iran using the enrichment culture technique. One bacterial strain designated QW4, identified as Proteus hauseri by morphological, biochemical and 16S rRNA gene sequencing was studied for its ability to tolerate different concentrations of sodium selenate (100-800 mM). Also, the disk diffusion method was performed to determine resistance to some antibiotics.
Results: Strain QW4 showed maximum minimum inhibitory concentration (MIC) to selenate (760 mM). The maximum selenate removal was exhibited at 35 ºC, while the removal activity reduced by 30.7% and 37% at 25 ºC and 40 ºC, respectively. The optimum pH and shaking incubator for removal activity was shown to be 7.0 and 150 rpm, with 60.2% and 60.3%, respectively. This bacterial strain was resistant to some antibiotics.
Conclusion: The concentration of toxic sodium selenate (1000 μg/ml) in the supernatant of the bacterial culture medium decreased by 100% after 2 days and the color of the medium changed to red due to the formation of less toxic elemental selenium. Also, our results imply that heavy metal pollution may contribute to increased antibiotic resistance through indirect selection.
https://ijm.tums.ac.ir/index.php/ijm/article/view/149
https://ijm.tums.ac.ir/index.php/ijm/article/download/149/131
ntestinal conditions was assessed and the number of viable Saccharomyces cerevisiae cells during 0 to 120 mines in these conditions was evaluated by a pour plate method using sabouraud dextrose agar.
Results: Results showed the shape of the beads was generally spherical, sometimes elliptical with a mean diameter of about 50–90 µm. Also count of viable probiotic cells obtained for all the microcapsules were above the recommended levels for a probiotic food. Also decrease of approximately 4 logs was noted in the number of free cells after 2 h of incubation at pH 2 and 8, when compared to decreases of about 2 logs in the all microencapsulated S. cerevisiae under similar conditions.
Conclusion: It is concluded that microencapsulation process was significantly able to increase the survival rate of Saccha- romyces in a simulated gastrointestinal condition (p<0.05)
https://ijm.tums.ac.ir/index.php/ijm/article/view/154
https://ijm.tums.ac.ir/index.php/ijm/article/download/154/538