JOURNAL OF MICROBIAL WORLD
Year:2013 | Volume:6 | Issue:1 (14)|Papers Count:9

Background and Objectives: Biosurfactants are a group of amphipathic molecules produced by microorganisms, which are constructed from two portions: hydrophilic and hydrophobic; these compounds increase biodegradation of insoluble pollutants. This study was carried out to isolation, identification and characterization of biosurfactant-producing Shewanella species from the Persian Gulf.Material and Methods: In this study, 25 biosurfactant producing strains were isolated from polluted sediments and seawater from Persian Gulf. Biosurfactant producing bacteria were isolated in Bushnell-Hass medium enriched with diesel. Then, dominant strains were screened by using quantitative and qualitative tests, including hemolysis in blood agar, oil spreading, drop collapse, emulsification activity and BATH test. Probable strains were identified by biochemical methods. Finally, dominant biosurfactant producing bacteria were recognized by using universal primers for 16s rRNA and sequencing.Results: In total of seven biosurfactant producing bacteria were isolated. Two of them, Shewanella E14 and Shewanella N4, were identified as predominant strains. Also, Shewanella algae and Shewanella upenei confirmed by molecular method.Conclusion: Based on the results, the isolates were able to produce biosurfactants and at the same time were able to degrade hydrocarbons. Therefore, the evaluation of applied potential of these strains for bioremediation of oil spillages is recommended.

Background and Objectives: S. simulans is a gram-positive cocci that can be isolated from skin and urine, as well as some clinical samples in human and animals, such as bovine mastitis. The present study was aimed to isolate and identify S. simulans, a lysostaphin-producing organism, from bovine mastitis and to test therapeutic property of this species against the staphylococcal infections.Materials and Methods: This cross-sectional study was done on the collected samples from breast of the cows afflicted to mastitis in Damghan, Semnan Province. The samples were cultured on nutrient agar and were examined based on Gram staining and biochemical tests. Then, the genomic DNA of the samples suspected for S. simulans were extracted. The accurate identification of the bacteria and tracking of lysostaphin gene were evaluated by using PCR and sequencing.Results: One out of 61 gram-positive isolated cocci from bovine mastitis samples was detected as S. simulans. This result was verified using 16S rRNA sequencing.Conclusion: This study is the first report of isolation of S. simulans, a lysostsphin-producing organism, from bovine mastitis. This species is potentially useful for extraction of lysostsphin which is applied for treatment of the infections caused by antibiotic resistance bacteria.

Background and Objectives: Mycoplasmal genital infections are often associated with devastating effects on quality of sperms, leading to male infertility. The aim of this study was to isolate Mycoplasma hominis from genital secretions of infertile men referred to the Kerman Infertility Center based on PCR method.Material and Methods: In this cross-sectional study, 58 semen samples were collected from the infertile men who were referred to the Infertility Center of Kerman from May 2012 to September 2012. Infertility condition was confirmed in all samples by performing a semen analysis. After genomic DNA extraction, DNAs were examined by PCR and the primers specific for both the genus Mycoplasma and species Mycoplasma hominis.Results: Overall, 22 samples (37.93%) were detected as Mycoplasml infection, among them 13 samples (22.41%) belonged to Mycoplasma hominis. Also, most of the Mycoplasmal infection were detected in the age group of 29 to 38 years.Conclusion: For the first time in Kerman, we could isolate Mycoplasma hominis from genital secretions of infertile men. The study showed that a relatively high percentage of asymptomatic infertile men were infected with this bacterium.

Background and Objectives: Enterococci are normal flora of alimentary tract of humans and many other mammals. Recently vancomycin resistant enterococci (VRE) have emerged as an increasingly important cause of nosocomial infections all around the world. The aims of this study were to determine frequency and antibiogram patterns of enterococci to vancomycin and also to detect the corresponding genes (vanA and vanB) in clinical isolates.Materials and Methods: This cross–sectional study was carried out on 54 enterococci strains isolated from clinical specimens (urine, wound, blood, …) obtained from the patients hospitalized in Shahid Mohammadi hospital, Bandar Abbass. RapID STR System Kit was used to identify species of isolated enterococci. Antibiogram pattern was examined by Kirby-Bauer disk diffusion method and CLSI criteria. MIC of vancomycin was determined by E-Test. Multiplex PCR and specific primers was used to detect vanA and vanB genes.Results: 38 out of 54 isolates (70.4%) of enterococci belonged to E. faecalis while E, feacium and E. hirea consist only and 10 (18.5%) and 3 (5.55%) of the isolates, respectively. Furthermore, one (1.85%) of each E.mundtii, E.durans and E.avium were isolated from these samples. These strains were mostly resistant to gentamicin and cephalexin while showed lowest antibiotic resistance to linezolid. 13 (24.10%) of the isolates were resistant to vancomycin. Van A and Van B genes were found in 69.23% and 15.38% of VRE strains, respectively. Two strains (16.38%) harbored both genes.Conclusion: According to the extensive frequency of vancomycin resistant enterococci, application of precautionary and management procedures are highly required. Furthermore, it is recommended to carry out the antibiogram assay for each patient, before the treatment process, in order to prescribe an appropriate antibiotic.

Background and Objectives: Polycyclic aromatic hydrocarbons (PAHs) were extensively spread in the environment and are regarded as one of the mutagenic and carcinogenic agents on living creatures. Among the vast variety of procedures for the elimination of contamination, biological removal is capable of transmuting pollutants into innocuous and nontoxic substances using less amount of energy, chemicals and time. The study was aimed at evaluating the possibility of growth of the indigenous bacteria isolated from oil-polluted soils, in the presence of PAH compounds in the laboratory, and also identifying them by using the method of PCR.Material and Methods: Specimens of the research were isolated from environmental gasoline and oil-polluted soils from the Isfahan City refinery. Initially, the native bacteria were separated from the contaminated soil with such compounds by utilizing a basic medium containing the concentration of 12.8 mg/l in 16 PAH compounds. Then, those bacteria which were able to grow and reproduce in the presence of the compounds identified through biochemical experiments and determination of genome sequence and consequently registered as new species.Results: The results obtained in the study substantiated that approximately 13.3% of the total heterotrophic bacteria possess a degradable ability of the hydrocarbons. After the evaluation of biochemical tests and gene sequencing, it was disclosed that the isolated indigenous bacteria belonged to Bacillus licheniformis ATHE9, Bacillus mojavensis ATHE13 and a particular species of Bacillus (ATHE10).Conclusion: The results of the present research verify the importance and proficiency of the native bacteria in the terms of the elimination of PAHs pollutions in contaminated areas.

Background and Objectives: Biological dissolution of pyrite leads to production of ferric ion and sulfuric acid. The produced ferric ion is a strong oxidant agent, which is able to dissolve different metal sulfides. This study aimed to examine effects of pH, pulp density and inoculation percent of bacteria on extraction rate of ferric iron ions from pyrite using a mixture of mesophilic bacteria.Material and methods: The pyrite sample was prepared from a pyrite lode in Midok copper mine. A mixture of mesophilic bacteria, including 40% Acidi thiobacillus ferrooxidans, 40% of Acidithiobacillus thiooxidans and 20% of Leptasprillum ferrooxidans, was used for all leaching tests.Results: According to results, effect of pH was more significant in bioleaching of pyrite and production of ferric ion than other factors. The maximum amount of produced ferric (1.93 g/l) was earned at pH 2, a pulp density of 25 g/l and inoculation percent of 15%.Conclusion: The desired amounts of byproducts of pyrite dissolution can be obtained by operational parameters such as pH, pulp density and inoculation percent in bioleaching. Thus, by taking into account the optimal conditions of mentioned parameters, it is possible to increase the production efficiency of valuable metals by hydrometallurgy processes of ferric ions.

Background and Objectives: Salmonella is one of the most important causative agents of food poisoning and gastroenteritis in humans. Using the standard culture methods for detection and isolation of Salmonella and also, the evaluation of bacterial characteristics by biochemical and serological tests, need to take 4 to 7 days, accuracy and skill of the lab staffs and quality of cultured media. Current study was carried out to assess PCR method for rapid detection of Salmonella in poultry meat samples and to compare its quality with two currently available standard culture and ELISA methods.Materials and Methods: This cross-sectional study was carried out on 60 samples of poultry meat collected from food stores of Tehran. The frequency of Salmonella was evaluated by using three microbiological methods culturing, ELISA (Kit SAL-VIA96; TECRA) and PCR (amplification of invA gene). Also accuracy, sensitivity and specificity of the methods were compared with each other.Results: In total of samples, the incidence of salmonella were 55%, 47% and 65%, by using culture, ELISA and PCR methods, respectively. Our findings showed that PCR based detection of salmonella using invA primers and only with a twenty hour pre-enrichment of samples in BPW is capable identifying Salmonella with high sensitivity and specificity (both 100%) in food samples in 24 to 30 hours.Conclusion: This study showed that PCR method has appropriate efficiency and sensitivity for rapid screening of Salmonella. Therefore, this technique is recommended to evaluate of Salmonella in food samples.

Background and Objectives: Shigellosis is a strictly human disease with no animal reservoirs. Annually, more than 150 million shigellosis are reported annually, which 600000 of the cases lead to death. The purpose of this study was to evaluate the antibacterial effect of two plant oils Salvia mirzayanii and Haplophyllum canaliculatum on Shigella dysenteriae.Material and Methods: The experimental study was performed on the flowering branches of two plants Haplophyllum canaliculatum and Salvia mirzayanii collected from natural habitats in Larestan city. Following extraction of the oils by Clevenger apparatus, constituents of the oils were identified using Gas Chromatography with mass spectrometry (GC-MS). Susceptibility of Shigella sp to the oils were determined based on disk diffusion method.Results: The maximum and minimum inhibition zone diameters were obtained by treatment of the bacteria with 20 and 0.625 micro liter/ disk, respectively. Based on the average of inhibition zone diameter on Shigella dysenteriae culture, Haplophyllum canaliculatum (with 13.78a hallow) is most effective than Salvia mirzayanii (with 11.33b hallow) (p<0.05).Conclusion: According to the antibacterial properties of the oil extracts, more studies is necessary to investigate other therapeutic features of these trees.