فصلنامه دنیای میکروب ها
سال دوم شماره 3 (پیاپی 4، پاییز 1388)

Nowadays, bacteria are widely used to recover copper from waste, ore, and concentrate. It is very important to understand bacterial performance in relation to materials with different mineralogy in order to select appropriate bacteria and improve bioleaching processes with high performance. As a consequence, the aim of this study is to investigate the effect of smelter dust and flotation concentrate mineralogy on copper recovery from the materials using mesophilic bacteria. The effect of processing material mineralogy on biological extraction of copper was investigated using a couple of material with different mineralogy, metallurgical dust and concentrate of Sarcheshmeh copper complex. Bioleaching experiments were performed by using mixed culture of A. ferrooxidans, A. thiooxidans and L. ferrooxidans from Sarcheshmeh Copper Mine in shaker utensils. Metallurgical dust mostly contained secondary sulphides products such as chalcocite and covellite, and concentrate mostly contained primary sulphides product such as chalcopyrite. The extraction rate of copper was achieved 0.835 g/L/day and 0.403 g/L/day from dust and concentrate, respectively. Also, kinetic studies showed that the rate constants of dust and concentrate were 0.125 day-1 and 0.010 day-1, respectively. The impact of mineralogical characteristics of the material on bioleaching operations was significant. Due to highly solubility rates of secondary sulphides, recovery rate and a higher overall copper recovery was obtained from dust in comparison to concentrate. Chalcopyrite oxidation was stopped at relatively low amounts (about 44%) and additional bioleaching time have not been improve it. The experiments showed that standard mesophilic culture at 35 ° C was very successful in bioleaching of secondary sulfide minerals, but bioleaching of primary copper sulfide minerals especially chalcopyrite by the culture was not effective.

The increasing rate of clarithromycin resistance in H. pylori is recognized as a significant contributing factor for treatment failure. The aim of this study was to representing a real-time PCR assay in comparison with disk diffusion method for detection of clarithromycin resistance in H. pylori. This Experimental study was performed on 45 H. pylori specimens isolated from gastrointestinal disorders patients. In all samples, presence of H. pylori was confirmed by using culture, rapid urease test and conventional PCR. Also, clarithromycin resistance were assessed by using CLSI (Clinical and Laboratory Standard Institute) protocol and real-time PCR using specific primers and probe for H. pylori peptidylteransferas region of 23S rRNA gene. Disk diffusion method identified 20 (44.44%) samples as susceptible and 25 (55.56%) samples as resistance to clarithromycin. But, real time PCR were identified samples as 20 (44.44%) with susceptible genotype, 5 (11.11%) with mix genotype and 20 (44.44%) as resistance to clarithromycin genotype. Also results showed that sensitivity of this assay was equal to 40 bacteria or 80 copy number of 23S rRNA gene. Results showed that Real-time PCR assay has high accuracy for identifying clarithromycin resistance in short time.

Amylase is one of the important industrial enzymes, which is used in the food industry, detergent production, glucose, textile, and paper making. Bacillus spp. are considered as a major amylase and protease producer microorganisms. The main purpose for the study is isolating amylase positive thermophile Bacillus Spp. from hot sources of Semnan province. Soil, fertilizer and water samples were collected from environment and the hot springs. After dilution preparation, samples were cultured on starch agar medium and then, potential of amylase producing was measured. Alpha-amylase enzyme activity of isolates was measured using di-nitro salicylic acid (DNS) method. Among 10 amylase producing isolated bacteria, two samples showed the highest amylase activity, 104.5u/ml and 61.2u/ml respectively. Although both the samples were diagnosed as Bacillus spp. one of them was belong to mesophile species while another one was detected as thermophile Bacillus. The thermophile Bacillus has been detected as a member of B. licheniformis according to Bergey’s Manual of Systematic Bacteriology. Due to high consumption of amylase enzymes and lack of producing the enzymes in Iran, The isolated Bacillus licheniformis in this study, with 61.2 U product per mL, can be introduced as candidate for produce the favorite amount of the enzyme after proper genetic manipulations.

E. coli O157:H7 is recognized to be one of the most important food-born pathogens causing hemolytic uremic syndrome (HUS). The purpose of this study was to evaluate the effects of probiotics Bifidobacteria spp. against growth or activity of E.coli O157:H7 was used in vitro.

This experimentally study was performed on strains isolated from clinical samples and standard E. coli O157:H7. All samples were enriched on BHI and TSA media and then, cultured on CT-SMAC. For confirmation of verotoxigenic E. coli, biochemical, serological testes, multiplex PCR and culture on Vero cell line were performed. Also, agar gel diffusion assay was used to detect the antagonistic activity of the probiotic bacteria against pathogenic bacteria.

According to used amount of probiotic, all the investigated strains showed a 15-30 diameter blanked area on Shiga producer E. coli O157:H7. The effect has been repeated in neutral pH, while organic acids had any meaningful effects on the pathogen strains.

Probiotics are able to inhibit growth of E.coli O157:H7 and it’s not only because of organic acid or low pH but also it’s because of produce other antibacterial agents.

S-layer is a outer protein in bacteria and archaea which intensifies bacterial pathogenicity due to inhibiting antibiotic’s entrance to cells. Because staffs and hospital surfaces have a major role in nosocomial infections, contaminating this source with S-layer and β–lactamase positive strains of B. cereus can lead to spread the antibiotic resistant nosocomial infections. In this study, in addition to determine the frequency of S-layer and β–lactamase positive strains in hospital environment, their function in inhibition of antibiotic’s entrance has been surveyed. The descriptive research was performed on 274 samples isolated from Azzahra hospital and Isfahan University during 2005/2007. In order to preparation of samples, 16 hours bacterial culture in TSA (Tryptone Soya Agar) were used and then electrophoresis with 10X SDS-PAGE were performed. Antibiogram were performed with Kirby Bauer method and β–lactamase production, with acidimetric method. From 247 isolated bacteria, frequency of B. cereus strains was %9.49. Eleven sample (84/6%) from 13 isolated B. cereus of staff hand and 1 sample (7/7%) from 13 isolated B.cereus from hospital surfaces produce S-layer nano-structure. According to antibiogram result, non producer S-layer strains, in comparative S-layer producer strains, were more sensitive to antibiotics and all S-layer producer B.cereus strains, produce β–lactamase. Result of this study show high prevalence S-layer and β–lactamase producer B. cereus strains in hospital, that lead to increase antibiotic resistance nosocomial infection and is necessary go on to reduce transfer virulence agent and antibiotic resistant in pathogen bacteria.

Obesity is one of the most important complication and risk factor for many diseases. Females at any ages except infant are at more risk for urinary tract infections than male. The aim of this study is assessment of relationship between excessive weight gain and UTI. This cross sectional study was performed on 200 of all pregnant women with UTI who referred to a governmental clinic in Larestan in 2009. All of them fulfill the questionnaires and then divided according to BMI of pregnant women. During third quarter of pregnancy (36-38 weeks of pregnancy), urine culture were followed. The rate of excessive weight gaining in all pregnant women was 43%.The rate of UTI were 4%, 4%, 5%, 7% and 10% respectively in BMI of 22, 23, 24, 25 and 26. UTI rate in excessive weight gain female were 12.5%, 11%, 16%, 12.5% and 12.5% respectively. Uti rate in BMI groups 27, 28 and 29 were 12.5%, 30% and 39% respectively. But UTI rate in BMI 30 and 31 were 50% and 60 % which is comparable with UTI rate of excessive weight gain. Also, results showed that UTI rate especially in female with higher BMI has significant relationship with increasing of pregnancy weight. The results showed that pregnancy weight gain can be considered as predictive

Infections with Hepatitis B virus in hemodialysis centers still remain as a major problem. The propose of this study is optimization and development of LAMP technique for assessment of HBV infection in serum of hemodialysis patients. This cross sectional study was performed on totally, 136 serum samples were obtained from the patients how referred to hemodyalis center in Tehran as: 52 serum samples from Mastafa khomaini hospital, 54 serum samples from Chamran hospital and 31 serum samples from Erfan hospital. After DNA extraction, 6 HBsAg specific primers were used for optimizing of reaction conditions and material concentration for LAMP. LAMP products were evaluated by adding 1% SYBER Green and electrophoresis stained by Ethidium-Bromide. LAMP sensitivity was determined as 4 particles in this study. In addition, LAMP technique Showed a high specify for detecting the viruses. Totally, 13and 7 cases of the serum samples of Mastafa khomaini were positive by LAMP and PCR respectfully. Also, 4 and 2 samples for second group and 2 and 2 samples for third group were positive respectfully by LAMP and PCR. The LAMP technique is a more sensitive and cost friendly system to detect HBV in comparison to conventional PCR.

Identifying plants with therapeutic properties is a great purpose of novel researches. This study aimed to evaluate anticancer properties of a group of plants with a fast screening method brine shrimp lethality test. This experimentally study were performed on 19 samples plants, taken from Campus of Bangalore University, with known anti-cancer activity, and three plant samples with known anticancer properties as controls. After extraction of mentioned plants, biological activity of them was assessed using brine shrimp lethality test. The results showed that 48.99% of the studied plants had inhibitory activity between 44 to 44.002%. Also, 47.70% of the investigated plants had little inhibitory activity. Also, three control samples have inhibition between 64.46 to 100. The results showed that brine Shrimp Lethality Test can be rapidly screening plants with anti-cancer activity.