فصلنامه دنیای میکروب ها
سال نهم شماره 3 (پیاپی 28، پاییز 1395)

Since biological methods for metal extraction, such as bioleaching, are environmental friendly, there are high demands to be replaced with the chemical and physical methods. The aim of this study was to extract gold from Muteh sulfide ore by two microbial phases.
Isolation of iron oxidizing bacteria was performed by adding mineral samples into 9k medium. At the first phase of the mineral bioleaching process, the ores were cut into different diameters, and after adding the rocks to the standard medium (1%), they were assessed after 7 days by x-ray diffraction method to study the existence of sulfide minerals. The cyanide producer bacteria were isolated by growing into TSA solid medium. In the second phase, the materials obtained from first phase were exposed to cyanogen bacteria, and the sediments were investigated by ICP.
Based on the results, the isolated bacteria from Sarcheshmeh mining were able to oxidize strongly ferrous and to remove pyrite from ore after 7 days. In the second phase, the isolated bacteria from Tonekabon arable soil could remove gold of (0.023 mg/l). The best range of Au recovery was produced in pH 7.
The isolated bacteria in this study were able to separate Au in two phases of microbial process, consisting of sulfide mineralization and recovery from aqueous form by cyanide bacteria.

The qnr gene is a plasmid carrying resistant genes involved in bacterial resistance to quinolone resistance plasmid factors. The aim of this study was to evaluate the presence of either gene qnr, a plasmid resistant gene, and aac (6) -Ib-cr, from Escherichia coli and Klebsiella spp isolated from clinical samples.
In this sectional study, 132 E. coli and 98 Klebsiella isolates were collected from patients with the UTI referred to the ayatollah Taleghani Hospital in Tehran. Antibiotic resistance was evaluated using Kirby-Bauer and CLSI criteria. After DNA extraction, qnr and aac(6)-Ib-cr genes were amplified using PCR method.
In this study, E. coli strains were resistant to ciprofloxacin and nalidixic acid in a ratio of 47.72 % and 62.12 %, respectively. Also, Klebsiella isolates were resistant to ciprofloxacin and nalidixic acid in a ratio of 38.77 % and 51.02 %, respectively. In the present study, the frequency of aac(6)-lb-cr, qnrA , qnrB, qnrS genes in E. coli were 30.18, 37.73, 67.92, 33.96 %. Also these frequency were 31.42, 22.58, 68.57, 31.42 % in Klebsiella.
This study showed high frequency of the ciprofloxacin resistant qnr gense in E. coli and Klebsiella isolates from Tehran.

High-risk human papillomaviruses (HPV) is the main cause of cervical cancer in women. Early diagnosis and immediate treatment are very helpful. Detection of this infection by traditional methods, such as pap smear, are very inadequate. This study was aimed to evaluate the HPV infection in women with cervical wounds using Multiplex PCR, and to compare the efficiency of this methods with pap smear.
This cross-sectional study was carried out on 50 samples from patient with cervical wounds attended to Khanevadeh Hospital in Isfahan. After extraction and purification of DNA, 5 types of HPV viruses were identified using Multiplex PCR. At the end, the results of these technique were compared with the results obtained from Pop smear.
Our results showed that 41 samples were positive to different types of HPV infection. All of these strains were detected using Multiplex PCR method. However, only 14 cases were reported positive by pap smear technique.
According to the results, pap smear has high error rate in HPV detection. But Multiplex PCR can provide a rapid, sensitive and affordable method for detection and screening of the viral infection.

Salvia leriifolia Benth. is a native medicinal plant species of Razavi Khorasan province, which possess valuable pharmacological properties including anti-microbial, anti-inflammatory, antioxidant, analgesic and sedative activities. In this study (basic/applied), antibacterial activity of essential oils from S. leriifolia against anaerobic bacteria cause oral-pharynx infections was investigated.
Aerial parts of S. leriifolia were collected at flowering stage from Bajestan in Razavi Khorasan Province. Essential oils were obtained using stem distillation methods and were analysed by GC-MS. Effects of different concentrations of essential oils (6.25, 12.5, 25 and 50 mg/ml) against Streptococcus mutans, Streptococcus pyogenes, Streptococcus sanguis and Actinomyces viscosus were evaluated by agar disk diffusion, hole-plate diffusion, common calibrated, agar dilution and broth dilution methods.
Among 35 compounds identified in S. leriifolia essential oils, β-pinene (23.35%), α-muurolol (17.11%), α-pinene (14.13%) and 1,8 cineole (13.25%) were the main compounds, respectively. Essential oil of S. leriifolia had significant inhibitory effect on the growth of all bacteria in a dose- dependent manner, so that maximum inhibitory effect was observed at concentration of 50 mg/ml. S. mutans (MBC=31.99 mg/ml, MIC=13.98 mg/ml) was the most sensitive bacterium and S. pyogenes (MBC=51.99 mg/ml, MIC=25.32 mg/ml) was the most resistance one.
Essential oils of Salvia leriifolia can be used as a natural product in herbal mouthwashes to control oral pathogens.

Endophytic bacteria live inside tissues of their plant host without causing visible symptoms, and in more cases are reported as plant growth promoting bacteria. This study was conducted to determine plant growth promoting affects of endophytic bacteria associated with Soybean (cultivar TMS).
In order to isolate endophytic bacteria from various parts of soybean (cultivar TMS), samples were collected from the farm of Islamic Azad University of Sanandaj. After genomic DNA extraction, 16S rDNA gene was amplified using PCR. Then, the PCR product was sequenced by BLAST. Strains were surveyed for IAA, and GA production ability was carried out using a randomized complete design in three replications.
The isolated bacteria were able to produce IAA in various amount 3.2 -12.14 µg/ml without tryptophan and in the presence of it, 7.2 -15.14 µg/ml. GA producing abilities were also 0.11-0.20 µg/ml for these isolates. Based on the 16S rDNA sequence, the isolated bacteria was belonged to Pseudomonas putida with 99% similarity.
This study is the first report of isolation of P. putida from Soybean (TMS cultivar). The endophytic bacteria isolated in this study can be used to promote plant growth.

Bioremediation is the promising technology for the treatment of the contaminated sites since it is cost-effective and will lead to complete mineralization. This study was aimed to isolation and phylogenetic identification of indigenous oil-degrading bacteria from soil of Karoon area in Ahvaz.
The crude oil contaminated soil of Karoon area in Ahvaz was sampled accidentally and under sterile condition. The amount of absorbable phosphorus was determined using Olson method and also, carbon, hydrogen and nitrogen by CHN meter device. Mineral salt medium containing 2% crude oil was used for isolation of oil eating bacteria. Following sieving the soil samples, the total carbon content of the soils were analysed by gas chromatography. Biochemical tests and PCR method were used to identify the dominant bacteria.
In this study, 44 bacterial strains were isolated, among them 20 isolates in the first and one in the second screening methods were selected, which was nominated as S31.This strain belonged to Bacillus licheniformis. The growth of the selected isolate in the media with 2% crude oil was better than the standard strain and remediated 84% of the crude oil in 30 days incubation time at about 30o C.
The selected Bacillus could use 2% of crude oil as source of carbon and energy and we suggest further studies on this bacterium in bacterial consortia.

Cancer cells are not capable of producing L-asparagine, and mainly are depended to the L-asparagine from the circulating plasma pools. L-Asparaginase (L-asparagine amidohydrolase EC 3.5.1.1) catalysis the conversion of L-asparagine to L-aspartate and ammonium. L-asparaginase is the first enzyme with anti-leukemic activity to be intensively studied in human beings. Isolation and identification of L-asparaginase producing bacteria from Jiroft microflora was the aim of this study.
In this sectional study, soil and water samples were collected from citrus orchards and waste of milk factory in Jiroft, Kerman province. The bacterial-producing L-asparaginase was screened on agar medium supplied with L-asparagine and phenol red indicator dye. L-asparaginase activity was detected on the basis of pink color around the colony. The best strains were finally identified using PCR method.
16S rRNA sequencing results showed that the best isolate-producing L-asparaginase belonged to the Bacillus genus. DJK23 strain produced the maximum L-asparaginase, approximately 165 U/ml. The our analysis showed that L-asparaginase was active in a pH rang of 5 to 8, with maximal enzyme activity at pH 7. It is mentioned that this enzyme retains 36% of its initial activity at pH 5.
Although L-asparaginase from bacteria has been extensively characterized, a similar attention has not been paid to Bacillus. These results showed that Bacillus L-Asparaginase has desirable activity in the presence of neutral and acidic pH, which can be considered as a therapeutic and industrial enzyme.

Lead is a heavy metal and persistent pollutant in the environment that enters through industrial wastewaters. The aim of this study was to isolate lead resistant bacteria from the industrial wastewaters, and to study the lead absorption by the isolated bacteria.
This descriptive study was performed on three wastewater samples. Nutrient agar medium containing different concentrations of lead acetate were used to isolate the lead resistant bacteria. Overall, 28 colonies were selected and their characteristics were determined. Of these, six colonies with the highest lead resistance were selected. The rate of lead absorption of these strains was measured using atomic absorption spectrophotometry. Four strains with higher lead absorption was identified using molecular method.
78.5% of the isolated resistant bacteria were Gram positive and 21.5% of the bacteria were Gram negative bacteria. Biochemical tests showed that 46.5% of the isolates were belonged to Bacillus sp. Of these, T5 had the highest lead absorption. Also, sequencing results revealed that the selected isolates are belong to Escherichia coli strain 789, Enterobacter cloacae strain GGT036, Bacillus tequilensis strain KM30 and Kurthia sp. VITA1 (T5).
The result of this study showed that the bacteria isolated from lead-containing wastewaters are highly potent for removal of this metal from polluted environments, and therefore can be appropriate candidates for bioremediation and biological treatment.