Screening of membrane active antimicrobial metabolites produced by soil actinomycetes using membrane models

     The focus of this study was antimicrobial membrane-activity of actinomycetes isolated from soils of Iran. In this work, soil samples were collected from desert and farming zones of Northern and Central Iran. A total number of 45 actinomycetes were isolated from the soil samples. In the primary screening performed to evaluate antimicrobial activity, isolated microorganisms were analyzed in terms of their general inhibition effects to indicator strains E. coli, C. albicans, and S. cervisae. It has been found that 12 actinomycetes, were effective against test microorganisms. In the secondary screening to determine membrane-active metabolites producing microorganisms, isolates having an inhibitory effect against test microorganisms, were analyzed for membrane activity using a Rapid Chromatic Detection method. Based on color changes that are easily identified by the naked eye and recorded by UV-vis spectrophotometery, two actinomycetes had membrane-activity effect and were stored for the sake of further study and identification

Isolation of membrane-active fraction of Streptomyces spp. from soil

Purpose: To isolate and characterize the membrane-active antimicrobial fraction and isolate metabolite produced by Streptomyces in soil samples from IranMethods: More than 60 Actinomycete strains were isolated from soil samples in Iran. A total number of 16 strains were studied using antimicrobial assay against Escherichia coli, Candida albicans and Staphylococcus aureus. Among these, three strains produced membrane-active metabolites based on artificial vesicle assay. Extracts of Streptomyces culture were obtained using ethyl acetate fractionation.Antimicrobial activity was evaluated by broth microdilution assay. Among these active extracts, one metabolite was isolated. Further fractionation and purification strategies were applied to finally identify the isolated metabolite using appropriate spectroscopic methods including thin layer chromatography (TLC), preparative thin-layer chromatography (PTLC), high performance liquid chromatography (HPLC),nuclear magnetic resonance (NMR) and liquid chromatography–mass spectrometry (LC-MS).Results: Three strains isolated from the soil samples, namely, strains 0811, 08346 and 08317 showed the highest antifungal and antimicrobial activity in Tryptic Soy Broth (TSB) and International Streptomyces Projects 2 (ISP2) medium in the range of 46.8 to 62.5 μg/ml. Strain 08346 was selected for further chemical profiling based on TLC pattern and membrane activity. It yielded a purified compound which was determined to be a novel aromatic amino alkyne, named Sourin.Conclusion: Streptomyces-produced 08346 strain demonstrates good antimicrobial activities against bacteria and yeasts, suggesting its potential as an antimicrobial membrane-active agent.Keywords: Actinomycetes, Secondary metabolites, Streptomycetes, Membrane-active agen

Yeast Enriched with Selenium: A Promising Source of Selenomethionine and Seleno-Proteins

Organic selenium compound such as selenomethionine plays a significant function in response to oxidative stress. Currently Saccharomyces cerevisiae is one of the best organisms that has ability to accumulate selenomethionine and selenium biotransformation. Addition of mineral selenium to medium culture is a very common practice in order to produce the selenomethionine and Seleno-proteins. Due to the toxicity of selenium for yeasts, selenium tolerant yeast isolation procedures are required. The aim of this investigation was to separate indigenous selenium tolerant S.cerevisiae strains which will not be affected by high selenium concentrations and are able to produce high levels of selenomethionine. In this study, 85 samples were collected from fermentative fruit. Screening was carried out in order to select high yeast cell density and also high selenomethionine accumulation. After confirming yeast strains, selected strains were cultured at a concentration of 25 mg/L sodium selenite and selenomethionine content was measured after 48 hours. The S18 isolate showed had maximum biomass production and selenomethionine accumulation (2655 ppm) and (3.73 g/L) compared to the other isolates.Highlights Selenomethionine is an important amino acid that has a significant role against oxidative stress.Addition of inorganic selenium to the yeast media culture leads to produce the selenomethionine.Saccharomyces cerevisiae is one of the best organisms for selenium biotransformation

Prevalence of Chlamydia trachomatis and Mycoplasma genitalium in Patients with Benign and Malignant Ovarian Cancer by Nested PCR Method

Background: Chlamydia trachomatis (C. trachomatis) and Mycoplasma genitalium (M. genitalium) are considered factors in cervical and ovarian cancer and are associated with flaky cell carcinoma of the cervix. The role of steady infection, leading to chronic inflammation, in the of ovarian cancer has received very little consideration, although a background of pelvic inflammatory disease (PID) is in a case-control study associate to higher risk for ovarian cancer. C. trachomatis, the most common and important cause of PID in the developed world is the genital and cervical infectious agent. The aim of this study was prevalence of C. trachomatis and M. genitalium in patients with ovarian cancer who referred to Imam Hossein Hospital of Shahid Beheshti University of Medical Sciences, Tehran, Iran.Materials and Methods: In this descriptive study that was conducted from January 2014 to April 2015, 124 samples were studied which obtained from patients with ovarian cancer who referred to medical centers of Shahid Beheshti University of Medical Sciences. After obtaining samples from ovarian cancer tissue by the pathologist, for extraction DNA, samples were transferred to the laboratory of university. To confirm the presence of C. trachomatis in samples of ovarian cancer, specific primers for the Major Outer Membrane Protein (MOMP) genes of C. trachomais, were designed and used Nested PCR method for detection of M. genitalium. Sequencing was performed on the PCR and Nested PCR product to confirm the presence of C. trachomatis and M. genitalium.Results: Out of 124 samples of ovarian cancer, 62 (50%) samples were malignant cancer and 62 (50%) were benign cancer as control group. From 65 malignant samples 14 (22.5%) were Chlamydia trachomatis positive. None of the tissue samples of benign cancer of ovary were positive for C. trachomatis. Notably, none of the 124 ovarian samples were positive in the M. genitalium standard PCR assay.Conclusion: The results suggest that the spread of C. trachomatis in the female with ovarian cancer may be common. This finding reflects a possible role of C. trachomatis in the carcinogenesis of ovarian tumors. C. trachomatis infection may play a relative role in the pathogenesis of ovarian carcinomas or it could facilitate its progression

Introduction to the Publication of the Journal of Medical Bacteriology in Iran

Over the past few decades, the science of microbiology in general and bacteriology in particular, has played a key role in fighting against infectious diseases and improving public health worldwide. During this period, we learned that as our knowledge of microbiology increases, we will face yet more scientific questions some of which may not be easy to answer. We have also learned that solving a scientific puzzle may open new sets of even more challenging questions. This is the nature of science and in our country, we as scientists, have an obligation to challenge these questions by sharing our knowledge, experience and our findings with other scientist through publications in scientific journals

Prevalence of Macrolide-Lincosamide-Streptogramin B (MLS B ) Resistance in Staphybcoccus aureus Isolated from Patients in Tehran, Iran

ABSTRACT Background and Objectives: Staphylococcus aureus is an important cause of nosocomial an

Membrane-active metabolites produced by soil actinomycetes using chromatic phospholipid/polydiacetylene vesicles

946-952Increased resistance of pathogens toward existing antibiotics has compelled the research efforts to introduce new antimicrobial substances. Drugs with new and less resistant-prone targets to antimicrobial activity have a high priority for drug development activities. Cell membrane seems to be a potential target for new antibiotic agent development to overcome resistance. In this study, A total number of 67 actinomycetes were isolated from the soil samples collected from desert, farming and mineral parts of Iran. We used a chromatic sensor as a membrane model that was set up for the target of antimicrobial metabolites of actinomycetes isolated from the soil. The sensors particles were composed of phospholipid and polymerized polydiacetylene (PDA) lipids. These polymers exhibited color change following interaction with membrane-active metabolites. The color change was due to structural disorder in the lipids following their interaction with membrane-active metabolites. The resultant color change was recorded by fluorescent microscope and easily recognizable by naked eye as well. Sixteen strains were isolated which produced antimicrobial metabolites and were effective against test microorganisms (Escherichia coli, Candida albicans and Saccharomyces cerevisiae ). A total number of 3 out of 16 strains produced membrane-active metabolites. These 3 strains were identified using 16s rRNA as Streptomyces sp and submitted to GenBank (accession no. JN180853; JN180854; JN180855)

Effects of sub-minimum inhibitory concentrations of gentamicin on alginate produced by clinical isolates of Pseudomonas aeruginosa

Background: Bacterial virulence factors may be influenced by sub-minimum inhibitory concentrations (sub-MICs) of antibiotics. The main purpose of this study was to investigate the effects of gentamicin at sub-MICs (0.5 MIC and 0.25 MIC) on alginate production of clinical isolates of Pseudomonas aeruginosa. Materials and Methods: The minimum inhibitory concentrations of gentamicin against 88 clinical isolates of P. aeruginosa were determined using the broth microdilution method. Alginate production of the isolates in the absence and presence of gentamicin at sub-MICs was assessed by the carbazole method. The presence of alginate in clinical isolates was confirmed by the detection of alginate genes (algD and algU) using the PCR method. Results: All the isolates had the ability of alginate production and were positive for algD and algU genes. sub-MICs of gentamicin significantly increased alginate production of 34 isolates (38.6%). On the other hand, in 49 isolates (55.7%), alginate production was significantly increased after treatment with sub-MICs of gentamicin. In five isolates (5.7%), the alginate production was reduced in exposure to 0.5 MIC of gentamicin while it was increased by gentamicin at 0.25 MIC. Conclusion: This study showed different effects of gentamicin at sub-MICs on the alginate production of clinical isolates of P. aeruginosa. Further research is highly recommended to understand the mechanism of different responses of P. aeruginosa isolates to the exposure of sub-MICs of gentamicin