Environmental Science
M. Noroozi; M.A. Amoozegar; A.A. Pourbabaei; N.S. Naghavi; Z. Nourmohammadi
Abstract
The current study was aimed at isolating and identifying the halophilic and halotolerant bacteria which can produce mercuric reductase in Gavkhuni wetland in Iran. Moreover, tracking and sequencing merA gene and kinetic properties of mercuric reductase in the selected strain were performed in this study. ...
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The current study was aimed at isolating and identifying the halophilic and halotolerant bacteria which can produce mercuric reductase in Gavkhuni wetland in Iran. Moreover, tracking and sequencing merA gene and kinetic properties of mercuric reductase in the selected strain were performed in this study. Soil samples were taken from Gavkhuni wetland and cultured in nutrient agar medium with 5% NaCl. To examine the tolerance of purified colonies to mercury, agar dilution method was administered. Similarly, the phylogenetic analysis based on 16SrRNA gene sequencing was conducted. To investigate enzyme activity of kinetic parameters, a spectrophotometer was used to measure the NADPH oxidation decrease at 340 n.m. The results showed that among the 21 halophilic and halotolerant strains isolated from Gavkhuni wetland, 4 were resistant to mercuric chloride. A strain designated MN8 was selected for further studies because it showed the highest resistance to mercury. According to phylogenetic sequencing of 16S rRNA gene and phenotypic characteristics, the strain was categorized in the Bacillus genus and nearly related to Bacillus firmus. This strain had merA gene. The mercuric reductase showed Vmax and Km values of 0.106 U/mg and 24.051 µM, respectively. Evaluation of different concentrations of NaCl at 37°C and pH=7.5 in mercuric reductase enzyme activity indicated that the enzyme shows 50% activity in concentration of 1.5 M. Optimum pH and temperature of enzyme activity were 7.5 and 35 °C, respectively. The results suggested that MN8 strain could be a proper candidate for bioremediation of mercury-contaminated environments such as industrial wastewaters.
Environmental Science
M. Ghiasian; A. Akhavan Sepahy; M.A. Amoozegar; S. Saadatmand; M. Shavandi
Abstract
Mud volcanoes are taken into consideration by geologists and oil industry experts have given their association with oil and gas reserves and methane greenhouse gas production in hydrosphere and atmosphere. Gomishan mud volcano phenomenon in the southeastern edge of the Caspian Sea, given its oil and ...
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Mud volcanoes are taken into consideration by geologists and oil industry experts have given their association with oil and gas reserves and methane greenhouse gas production in hydrosphere and atmosphere. Gomishan mud volcano phenomenon in the southeastern edge of the Caspian Sea, given its oil and gas resources, has been studied by some geologists in terms of geology and tectonics but not in terms of microbiology. Accordingly, it seems necessary to study this phenomenon from the perspective of microbiology in order to identify prokaryotes living in this area. Prokaryotes diversity in Mud volcano has been studied by cultivation techniques, fluorescence in situ hybridization, and denaturing gradient gel electrophoresis of PCR-amplified fragments of 16S rRNA genes. Total cell abundance in the mud volcano from 1×101-6×101per milliliter was determined by 4', 6-diamidino-2-phenylindole direct count. The detectable proportion of Archaea to Bacteria in the community by FISH was one to five. High viable counts (1 – 3 × 106) were obtained in culture media. A total of 122 isolates were obtained, 46 colonies were selected based on primarily morphological and physiological traits, and their 16S rRNA sequences were determined. The isolated genera included Halomonas (20%), Arthrobacter (5%), Kocuria (5%), Thalassobacillus (5%), Marinobacter (20%), Paracoccus (5%), Roseovarius (5%), Jeotgalicoccus (5%), Bacillus (15%), and Staphylococcus (15%). Regarding DGGE analysis, selected bands were obtained from the gels, reamplified and sequenced. Overall, 75% of the bacterial sequences were related to Rahnella and 25% related to Serratia.