Bacterium Pseudomonas aeruginosa is an opportunistic human pathogen and one of the most important causes of nosocomial infections in a wide range of immunocompromised patients including those with malignancies, cystic fibrosis, and burns. This bacterium produces many virulence factors and is highly resistant to lots of common antibiotics due to its biofilm formation. The production of many virulence factors in this bacterium is under the control of quorum sensing systems (QS). The QS is an attractive target for the development of novel therapeutics. Eugenol is the major component of clove (Eugenia caryophylata) oil. The previous studies have shown its antibacterial activities. This study aimed to determine the in vitro anti-QS activity of eugenol on QS-regulated biofilm formation and virulence factors production in P. aeruginosa strains. The minimum inhibitory concentration (MIC) of eugenol was determined against two strains of this bacterium ATCC 27853 and PAO1, and three clinical isolates. Then the effect of eugenol on bacterial proliferation was determined by monitoring the growth curve. The biofilm formation, the production of exopolysaccharide (EPS), pyocyanins, rhamnolipids, the motility of swimming, swarming, and twitching were evaluated after the eugenol treatment. The MICs against two strains of the bacterium ATCC 27853 and PAO1 were obtained 0. 3% and 0. 6% (v/v), respectively. Different concentrations of eugenol (≤ 0. 15%) significantly reduced the production of virulence factors including pyocyanin and rhamnolipid. The biofilm formation, EPS production, and swarming, swimming, and twitching motility were also reduced after the eugenol treatment. In general, according to the results of this study, the use of eugenol, as a potent QS inhibitor and anti-biofilm agent, could be an effective therapeutic strategy against P. aeruginosa infections.

Background & Aims: Quorum Sensing is a mechanism by which orchestrate the expression of many genes in bacteria. Therefore, any interference with the system will inhibit bacterial infections. The principal purpose of the research was to evaluate the potential of anti-quorum sensing of Rosa damascena and Stevia rebaudiana against Staphylococcus aureus. Materials & Methods: Ten isolates of Staphylococcus aureus were collected and identified. Plant species were collected from gardens of Fars province and extracted using 96% ethanol. The effect of anti-QS properties of the plant extracts was evaluated using Chromobacterium Violaceum CV026 biosensor. Furthermore, Biofilm production of the strains was investigated through the microtiter plate. In addition, the phytocompounds of Rosa and Stevia were identified by GC-MASS. Results: The results showed that Rosa damascene (19± 0. 5) and Stevia rebaudiana (17± 0. 5) extracts significantly (P<0. 05) possess anti-QS activities. Moreover, both extracts had antimicrobial activity and anti-biofilm properties. The results of the GC-MASS analysis also disclosed that the extract of rosa contains compounds such as Geraniol, β-Citronellol and Linalool, and also the extract of Stevia has compounds similar to Furfural, Terpinen-4-ol, Linalool, and α-Pinenem which could interfere with bacterial QS. Conclusion: According to the anti-biofilm and anti-QS properties of Rosa and Stevia extracts, the active compounds of the extracts, with an accurate evaluation, could be considered as an appropriate approach for bacterial treatment.

Pseudomonas aeruginosa is an important opportunistic pathogen that causes mastitis resistant to treatment in lactating dairy cows. This bacterium is a nosocomial pathogen and can be also transmitted to humans through food. Antibiotic resistance and biofilm production are two important factors in the pathogenesis and long-term persistence of Pseudomonas aeruginosa infections. Pseudomonas aeruginosa has two complete Quorum sensing systems that cause the activation of pathogenic genes. The aim of this research was to study of frequency of Quorum sensing genes in Pseudomonas aeruginosa isolated from bovine mastitis in Maragheh city in 2022. In this descriptive cross-sectional study, 200 cows with clinical mastitis were sampled and 60 Pseudomonas aeruginosa isolates were identified after biochemical and staining tests. Then the isolated samples were investigated for the presence of lasI and rhlR genes by PCR method. The frequency of lasI and rhlR genes was observed in 2 (3. 33%) and 8 (13. 33%) isolates, respectively. Also, 2 isolates (3. 33%) harbored both lasI and rhlR genes simultaneously. In this research, the frequency of Quorum sensing genes was less than in previous studies on samples isolated from human cases, which geographical differences and ecological origin of bacterial isolates can play a significant role in justifying its cause.

The earth landscape is always changing due to human activities and natural phenomena. Therefore, in order to optimize the management of the natural areas, knowledge of the trend and extent of land cover / land use changes is considered necessary, and the estimation of these changes is of great importance. Reviewing these changes through satellite images and predicting and evaluating their potential through modeling can help environmental planners and natural resource managers to make more informed decisions. In the present study, quantitative detection and evaluation of changes in vegetation was performed in the areas with combat desertification projects, Shahdad and Bam in Kerman province and Garmsar in Semnan province, during a 30-year period within 1987, 2002 and 2017. The NDVI vegetation index and land use maps were produced using the ETM + TM and OLI satellite images in the three corresponding periods for the vegetation lands/non-vegetation lands, and agricultural lands. The Kappa coefficient of 0. 83 to 0. 86, 0. 91 to 0. 92, and 0. 94 to 0. 95 was calculated for 1987, 2002, and 2017, respectively, and the total accuracy was between 88 % and 97 %. After providing the land use maps in different years, the monitoring of land use changes was investigated using the change detection methods. According to the trend of changes during the studied periods, our results showed that the vegetation lands in these three areas had an increasing trend, and the non-vegetation lands were turned to vegetation lands over time. Moreover, an increasing trend was found for the agricultural lands during these three periods. Finally, the cost-effectiveness of projects implemented in the studied areas was calculated and evaluated.

Proper sampling of the spatio-temporal field induced by a source and its recovery from the limited and discrete samples of the sensor network are two important steps in environmental monitoring of the diffusion thermal field. Sampling by sensor networks has limitations: 1) limitation in the number of sensing nodes, which limits the spatial resolution. 2) battery life of the sensor node, which limits the power consumption and temporal sampling rate. Compressive Sensing (CS) is a traditional method to overcome sampling problems of sensor networks, while an efficient scheme is required to recover the field from the samples. In this paper, Diffusive Compressive Sensing (DCS) is proposed to use Partial Differential Equations (PDE) constraint to model the inherent structure of the spatio-temporal field as side information in the compressive sensing problem. According to the method of estimating the time derivative parameter in the PDE at each moment, the DCS-I and DCS-II methods are presented. Also, to better model the dependence between time frames, Kronecker Diffusive Compressive Sensing (KDCS) is proposed in which the structured sensing matrix designed using the Kronecker product. Simulation results indicate that the proposed KDCS method outperforms existing methods.