JOURNAL OF MICROBIAL WORLD
Year:2015 | Volume:8 | Issue:2 (23)|Papers Count:8

Background & Objectives: Legionella pneumophila is an aerobic gram-negative bacterium and etiology of legionnaires disease. The ralF and lepA genes belong to the members of type IV secretion system are essential for intracellular growth and survival of bacteria. The aim of this study was to isolate L. pneumophila from bronchoalveolar lavage (BAL) fluid samples and the frequency of lepA and ralF genes.Materials & Methods: This cross-sectional study was carried out on100 BAL fluid samples collected from the patients suffering of respiratory infections who visited Charmahal-O-Bakhtiri health centers. Isolation of L. pneumophila was performed using a specific medium (BCYE). Then, all the samples were evaluated using PCR and specific primers designed for 16S rRNA gene. Furthermore, the frequency of lepA and ralF genes was determined using PCR method.Results: Overall, 9% of the total 100 samples were infected to L. pneumophila. Furthermore, molecular tests showed that 12 cases out of these samples were positive for this bacterium. The frequency of the ralF and lepA genes in these samples were measured 41.66 and 25%, respectively. In addition, 8.33% of the samples carried both genes.Conclusion: Our studies indicated high frequency of the ralF and lepA genes in L. pneumophila isolated from this area. It is possible to determine L. pneumophila in fresh samples based on PCR technique without using in media. Furthermore, PCR technique is faster and more accurate for detection of L. pneumophila in bronchoalveolar samples in comparison to culture method.

Background & Objectives: Glycopeptides such as vancomycin and ticoplanin are commonly used as antibiotic of choice for treatment of infections caused by methicillin-resistant Staphylococcus aureus. Following first reports of vancomycin resistant strains, the presence and distribution of these bacteria have been continuously investigated in the clinic centers. This study was aimed to investigate the distribution of glycopeptide resistant S. aureus isolated from Shohada hospital during a period of three years.Materials & Methods: This cross-sectional study was carried out on 182 S. aureus strains isolated from wound orthopedic patients in three years. Resistance against glycopeptides, linezolid and ciprofloxacin were examined by disk agar diffusion method. Screening plate method containing 6mg / ml of vancomycin was used for resistance against vancomycin.Results: Among the 182 isolates, only 2 cases (1.09%) were confirmed as vancomycin-resistant S. aureus, VISA strains. In isolates from the last year of sampling, the resistance was controlled. Among total isolates, in 31 isolates (17%) demonstrated intermediate reaction against ticoplanin.Conclusion: Significant differences are indicated between glycopeptide resistances isolated from different years, despite a report of two VISA isolates in our center, which showed that the resistance controlled by the authorities.

Background & Objectives: Bacterial canker in walnut is caused by Brenneria nigrifluens. The prevalence of this disease has been increasing in recent years and it is a serious threat to walnut tree in the appropriate conditions. The aim of this study was to isolate and identify the prevalence bacterial walnut canker in Lorestan and to determine their pathogenesis in the raw walnut.Materials & Methods: This cross-sectional study was carried out on 105 branches and trunk bark walnut trees suffering of the symptoms of shallow bark canker. After purification and isolation of the disease agents, the bacteria were identified based on phenotypic characteristics. Next, the results were analyze by Ntsys-pc version 2.02 software. The PCR reactions were performed for more accurate identification of the isolates. Overall, five bacterial isolates were selected to study their pathogenesis on the walnut fruits and trunks.Results: According to the results of phenotypic characteristics of isolates, these strains were classified as B. nigrifluens. Furthermore, based on numerical analysis of the strains with 94% similarity, these isolates were classified into four groups. All isolates produced an expected 255 bp band in the PCR reaction. These strains caused necrotic area on fruit with reddish brown ooze.Conclusion: The differential phenotypic tests, the pathogenicity test on the raw fruits and specific primers are reliable methods for diagnosis of the etiology of this disease. In our knowledge, the present study is the first report regarding the occurrence of this disease in Lorestan province and also first report of the pathogenicity of B. nigrifluens on fruit in Iran.

Background & Objectives: The halophilic Archaea are strong sources of carotenoid pigments. These compounds are used in the pharmaceutical industries and fisheries due to their antioxidant, anti-tumor and pigmentation properties. This study was aimed to increase the production of pigment Carotenoids by the strains Haloarchaea lipolitical.Materials & Methods: This experimental study was performed on H. lipolitical, isolated previously from water sources located at Bushehr. Effects of several factors, temperature, pH, carbon sources, nitrogen sources, different percentages of sodium chloride ions and the impact of heavy metals were compared with the standard curve to optimize the pigment production in H. lipolitical.Results: Statistical analyzes showed the optimal amount of carotenoid pigment production conditions at a temperature 35oC for 88 hours (39.3 mg), pH 8 for 120 hours (15.77 mg), casein peptone nitrogen source and yeast extract for 72 hours (13.28 mg), NaCl 16% for 96 hours (15.77 mg), starch carbon source for 96 hours (4.44mg) and the presence of manganese sulfate for 120 hours (59 mg).Conclusion: Due to non-pathogenicity of Archaea, the availability of suitable sources for their growth and high levels of salt in the culture, this strain can be used for the production of carotenoids in various industries.

Background & Objectives: Environmental pollution to toxic heavy metals is one of global environmental problems. Microorganisms perform several mechanisms to reduce the intracellular concentration of toxic pollutants. The objective of this study was to identify zinc resistance determinant (czcC gene) in zinc resistant Pseudomonas stutzeri SEE-1 isolated from soil.Materials & Methods: The strain was performed on a P. stutzeri strain isolated previously from soil by culture on MTBE (Methyl Tertiary Butyl Ether). The maximum tolerable concentrations of zinc ions and zinc oxide nanoparticles were determined. PCR amplification was used to investigate the czcC gene. The nucleotide sequence was translated into protein sequence and its sequence was compared with other similar sequences in other zinc resistant bacteria.Results: The highest tolerable concentrations of zinc ion and zinc nanooxide was measured at 4mM and 600 mg ml-1, respectively. The primers used for the amplification of the Zn-resistance gene (czcC) yielded a approximately 250 bp band. The comparison of czcC with other sequences in the gene bank database demonstrated 100% similarities with czcC gene in P. stutzeri 1501.Conclusion: The results of this study showed that soils contaminated with heavy metals are potential sources for the isolation of resistant strains to heavy metals and metal oxide nanoparticles. Understanding the genetic basis of bacterial resistance to heavy metals can improve application of these natural mechanisms to provide a safer environment for all living things.

Background & Objectives: Formaldehyde is a toxic and hazardous compound and s known as one of the mutagenic and carcinogenic agents in living creatures. Among a variety of procedures designed for the elimination of contamination, biological removal is capable of converting pollutants to innocuous and nontoxic substances using less amount of energy and chemicals. This study was aimed biodegradation of formaldehyde by the bacteria isolated from Wastewater of Paint Production (Pars Negin Nama).Materials & Methods: In this analytical study, samples were taken from paint production factory effluent. The samples were added to CM and MSM media to isolate bacteria. The bacteria were analyze based on morphological and biochemical characteristics. The bioregdaration ability of bacteria in MSM containing formaldehyde media was evaluated in absorbance at 600 nm using a spectrophotometer. The identity of bacteria was determined based on sequencing of 16SrRNA.Results: The result showed that the best formaldehyde degrading bacteria belonged to a new strain referred to as Bacillus sp. Safa. Toneka. This strain was able to degrade formaldehyde 1500 ppm formaldehyde in MSM agar and 2000 ppm formaldehyde in MSM broth after 48 hour.Conclusion: The results of the present research showed the ability of bacteria in the terms of the elimination of formaldehyde in contaminated areas.

Background & Objectives: Detection of the microorganisms resistant to toxic metals is the first step in the process of bioremediation. The purpose of this study was isolation of silver-resistant bacteria, determination of their minimum inhibitory concentration (MIC) and investigation on the bio sorption in vitro.Materials & Methods: Sampling was carried out from the wastewater of two Silversmith’s workshop in Isfahan and effluent of the wastewater treatment plant phase 2 input in Shahinshahr. The agar dilution method and PHG II culture medium containing concentrations of 0.5, 1, 2, 4, 8, 16, 32 mM of Ag (NO3)was used to separate the metal-resistant bacteria and determine the minimum inhibitory concentration (MIC). Finally, the rib otyping method was used to identify the silver-resistant bacteria.Results: In this study seven silver-resistant bacteria were isolated, among them Ag5 showed the highest resistance to silver (MIC = 6mM). Based on the molecular analysis, this isolate belonged to a new strain, called as Stenotrophomonas maltophilia strain MS8, and its formation was deposited as KP742984 in Gene Bank (NCBI). This strain was able to absorb 11.39% of silver from medium in vitro after 120 minute and could growth well in the presence of silver.Conclusion: According to the results of this study, it seems that this isolate is a good candidate for biological removal of silver from contaminated wastewater in the future.

Fusarium sp. is one of the most important agents that infect the root and crown of canola in worldwide. The aim this survey was to identify Fusarium species associated with crown and root of canola grown in Khuzestan province and pathogenicity of dominant species in this area. Following isolation and purification of the samples, specific media were used to identify the isolates. The isolates were used for infection of the trees in an accidental manner. In this study, a total of 73 isolates of Fusarium were isolated. F. solani, with 23 isolates was the most dominant fungi in these samples while F. oxysporum and F. verticillioides showed the lowest number of isolates. In this study, F. nigamai, F. verticillioides and F. clamidosporas were isolated for first time from crown trees grown in Iran. The pathogenesis tests showed that F. solani and F. equiseti showed the highest pathogenesis. Based on the severe infection in the roots in these samples, it is recommended to investigate the volume of damages and appropriate strategies for control of pathogenesis of Fusarium in farms.