فصلنامه دنیای میکروب ها
سال شانزدهم شماره 1 (پیاپی 54، بهار 1402)

CRISPR  system (clustered regularly interspaced short palindromic repeats) and Cas portions is a part of the immune system in microorganisms. The cas genes could be involved in reducing antibiotic resistance in bacteria. The aim of the study was to investigate the frequency of cas genes of the CRISPR/Cas system in Extended Spectrum        Beta-Lactamase (ESBL) producing Escherichia coli isolated from urine culture of patients with urinary tract infection.

In this cross-sectional study, 437 positive urine culture samples were collected from Chalus hospitals. Escherichia coli strains were isolated based on standard biochemical tests and Enterobacteriaceae commercial diagnostic kit, as well as antibiotic sensitivity using disc diffusion method (Kerby Baer). Combined disk test was conducted for isolates that were resistant to at least one of the third-generation cephalosporins in the foregoing antibiotic susceptibility test. Molecular identification of cas1,cas2,cas3,cas7 and cas5 genes was performed using the PCR method.

Out of 437 urin culture samples, 106 samples (24.3%) had E.coli infection. The highest antibiotic resistance was associated with ampicillin (99%). Among the resistant isolates, thirty isolates (88.3%) were ESBL producing. cas1 gene had the highest frequency (96.2%) and other cas genes had almost the same frequency.

The results of the present study showed that a significant percentage of E. coli isolates had ESBL phenotype, which may be due to the presence of broad-spectrum beta-lactamase genes in these samples. Besides,  it was shown that there is no relationship between the presence of ESBL phenotype and the distribution of cas genes.

Flagella and motility are important factors in bacterial colonization and pathogenicity. flaB is one of the important genes encoding the flagellar protein, which produces antibody against this gene play major role in immunogenesis. The aim of the present study was to make a flaB gene construct and to evaluate its expression in eukaryotic cells as a candidate for vaccine production. 

flaB cloning and subcloning was done in pTZ57RT and pBudCE4.1 plasmids. Then the accuracy of the obtained clones confirmed by PCR, double enzyme digestion and sequencing. After transferring the confirmed gene construct to the animal cells, the gene expression was checked at the level of transcriptome and proteome by RT-PCR and SDS-PAGE methods. 

PCR results showed amplification of a1563 bp segment related to flaB gene. Desired gene cloning had confirmed by PCR, double enzyme digestion and sequencing. The observation of 1563 bp and 56 kDa bands from RT-PCR and SDS-PAGE indicates the successful expression of flaB in HDF cells.

The recombinant gene construct can express the FlaB protein in animal cells. Therefore, according to the results, this construct can be used as a candidate to produce an effective gene vaccine against Helicobacter pylori.

The spread of drug resistance and limited effects of antibiotics on the pathogenic biofilms along with the increasing number of hospital infections have imposed heavy costs on the healthcare system. In the present study, quercetin-barium phosphate hybrid nanostructures were fabricated and characterized in order to improve their antibiofilm activity.

To prepare hybrid nanostructures, barium sulfate was added to sodium phosphate buffer containing quercetin (0.1 mg mL–1), the reaction mixture was sonicated for 10 min, and the obtained precipitate was collected. To obtain the hybrid nanostructures with the maximum immobilized quercetin, the concentrations of phosphate buffer and barium sulfate were examined in the range of 50–250 mM and 10–50 mM, respectively. The prepared hybrid nanostructures were characterized using scanning electron microscopy, infrared spectroscopy, and X-ray diffraction analysis, their effects were evaluated in preventing and destroying bacterial biofilms as well.

The immobilization yield of quercetin within hybrid structures was 95%. The scanning electron microscope images showed fiber-like structures with smooth, knot-free, and uniform surfaces. Quercetin-barium phosphate hybrid nanofibers significantly inhibited the biofilm formation in Pseudomonas aeruginosa and Staphylococcus aureus by 100% and 80%. Also, in the presence of the immobilized quercetin (500 mg L–1), biofilms of Staphylococcus aureus and Bacillus subtilis were destroyed by 75% and 70%.

Due to the notable antibiofilm properties of quercetin-barium phosphate hybrid nanofibers, they could be useful in medical devices, and therapeutic and environmental processes.

Soil contamination by petroleum compounds and salt often occurs simultaneously. The aim of this study was the isolation of halotolerant bacterial strains with the ability to remove different concentrations of polycyclic aromatic hydrocarbons (PAHs).

In the present original study, petroleum-contaminated soil samples were collected from Dehlran area. To isolate bacterial strains degrading PAHs, PAHs- enriched media were used as the sole source of carbon and energy. The ability of the isolates to tolerate different salt concentrations was investigated. Based on its capacity to produce biosurfactants, a suitable bacterial strain was chosen and the biodegradation of various types of PAHs was evaluated. The effects of the molecular weight and initial concentration of different types of PAHs on the strain’s cell growth and biodegradation were investigated.

Among the isolates, Labedella gwakjiensis strain KDI, with the ability to grow at concentrations greater than 3% salt and produce biosurfactants, was selected. The results demonstrated that this strain could biodegrade various types of PAHs, and that the molecular weight and initial concentration of PAHs, which have a direct effect on cell growth, indirectly affect the biodegradation rate.

Salt is considered as a deterrent in biodegradation. Hence the use of halotolerant bacterial strains capable of biodegrading PAHs is critical in removing these pollutants from the environment.

Citrus psorosis virus is the causal agent of one of the most important viral citrus diseases in the world and has been detected from the citrus orchards in the east of Mazandaran province, IRAN. Because of the simultenious presence of various strains of this virus in infected citrus samples, molecular detection methods like PCR are not able to detect this virus with high accuaracy. In this research, we introduce a method for the precise detection of Citrus psorosis virus.

Detection and Identification of infected samples performed by triple antibody sandwich indirect-ELISA (TAS-ELISA) method and monoclonal antibody from symptomatic Thomson orange and Unshiu tangerine samples with suspicious symptoms to CPsV infection in Sari, Neka and Ghaemshahr districts of Mazandaran. Infection in samples tested by ELISA and confirmed by RT-PCR. Extraction of CPsV-dsRNA (Double-strand RNA) from infected samples was done by CF-11 column. Molecular hybridization performed by DIG labeled cDNA probe.

Exploring the electrophoretic pattern of dsRNA extracted from the CPsV infected citrus samples by using ELISA and RT-PCR methods, indicating the presence of CPsV genomes with the molecular weights of 920 bp and 2500 bp in infected samples. The presence of CPsV in the samples was also confirmed by using molecular hybridization and designed probe. 

The major advantages of the hybridization method relating to the dsRNA electrophoretic mobility is the simultenious detection of the all citrus psorosis virus strains within the infected citrus samples. This way can separate virus isolates.

The rot caused by strawberry gray mold (Botrytis cinerea) is one of the most important rots causing damage in the field and market. The purpose of this research is that biological control agents and compounds inducing plant defense reactions seem to lead to a reduction in the frequency of spraying or not spraying fungicide compounds on the crop.

Different isolates of B. cinerea were collected from greenhouses and farms in Kurdistan province, and their morphological and molecular characteristics were determined. In the following, different concentrations of salicylic acid (SA) either individually or in combination with different Trichoderma species were investigated in the laboratory and greenhouse on strawberry gray mold.

In the comparison of averages, the highest percentage of inhibition in the cross-culture between Trichoderma spp and Botrytis sp. is related to T. orientalis (60.82%), the highest percentage of inhibition of the extracellular secretions of Trichoderma isolates on the growth of Botrytis in each two concentrations of 15 and 30% related to T. ceramicum was 85.57% and the effect of volatile compounds of different Trichoderma species on the growth of B. cinerea showed that the highest percentage of inhibition was related to the treatment of T. asperellum isolate with 63.70%. Investigating the effect of salicylic acid in preventing the mycelium growth of botrytis fungus in the laboratory showed that with increasing concentration of salicylic acid from 1 to 2 millimolar, the inhibition percentage of Botrytis cinera increased to 61%.

The results of the experiment showed that the use of some Trichoderma species along with salicylic acid increases the resistance and control of strawberry to gray mold disease in the field and laboratory.