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In this study, we investigated the effectiveness of both single and hybrid systems, incorporating UV photolysis and a Moving Bed Biofilm Reactor (MBBR), for treating synthetic wastewater contaminated with petroleum hydrocarbons. Petroleum hydrocarbons pose significant environmental threats due to their high toxicity, stability, accumulation potential, and resistance to biodegradation. In the hybrid system, the wastewater underwent chemical treatment first and then was introduced into the biological reactor. For the photolysis system, we explored the impacts of different concentrations and various radiation powers of UV-C lamps. Optimal conditions were determined to be a Chemical Oxygen Demand (COD) of 350 mg/L and a radiation power of 80 W. In the MBBR system, various concentrations were introduced into the reactor, achieving a maximum removal efficiency of 85% for an initial COD of 1000 mg/L over 72 hours with a 50% filling capacity. In the hybrid system, we achieved a remarkable hydrocarbon removal efficiency of 99% after 123 hours. Although the operational time of the hybrid system was relatively long, it demonstrated itself as a suitable treatment process compared to other conventional methods for removing these challenging, hard-to-biodegrade compounds.

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Background: Pseudomonas aeruginosa is considered an opportunistic pathogen; several reports indicate that the organism can also cause infections in healthy hosts. Four effector proteins have been described in P. aeruginosa: exoU, exoS, exoT, and exoY. These genes that are translated into protein products related to type III secretion systems. Materials and Methods: A total of 134 samples were isolated, and P. aeruginosa was identified using biochemical tests. Bacterial genomic DNA was extracted, and the presence of the exoSand exoUgenes were detected by PCR. Biofilms were formed by culturing P. aeruginosaon glass slides in rich medium. Results: The exoU(73%), exoS (62%) genes were detected from infections caused by P. aeruginosa in urinary tract infection patients. Among the 119 strains isolated from patients with urinary tract infections. Conclusion: An improved understanding of virulence genes and biofilm formation in P.aeruginosa may facilitate the future development of novel vaccines and drug treatments.

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Background: Emergence of drug-resistant bacteria has highlighted the need to identify new and more efficient antibacterial agents. The aims of this study were to evaluate the antibacterial activity of dill (Anethum graveolens) seeds essential oil and to investigate the effect of cumin (Cuminum cyminum) seeds alcoholic extract on biofilm formation ability of Klebsiella pneumoniae.
Materials and methods: This experimental study was carried out at the Faculty of Medicine of Kurdistan University of Medical Sciences in 2014. Activity of dill seeds essential oil was evaluated based on the inhibition zone diameter and minimum inhibitory concentration (MIC) against some important pathogenic bacteria including: Vibrio cholerae, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Furthermore, the effect of sub-inhibitory concentrations of cumin seeds alcoholic extract was evaluated on biofilm formation ability of K. pneumoniae. The biofilms were formed on semi-glass lamellas and observed by a scanning electron microscope.
Results: Dill essential oil showed a good to moderate activity against the tested strains. The highest antibacterial activity was observed against S. aureus (inhibition zone of 15 mm and MIC of 0.62 mg.mL^-1) and V. cholerae (inhibition zone of 14 mm and MIC of 0.7 mg..mL^-1). The cumin alcoholic extract had no effect on biofilm formation ability of K. pneumoniae.
Conclusion: The results of this study showed the presence of antimicrobial compounds in dill extract. The cumin alcoholic extract was not able to inhibit biofilm formation ability of K. pneumoniae. Because of the medicinal plants properties, it is valuable to search for promising herbs and novel chemical compounds.

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Aims: Streptococcus mutans (S. mutans) is part of human oral cavity microbiome and is known to be responsible of dental caries. The aim of this study was to evaluate the inhibitory effects of Punica granatum, Ricinus communis, and Allium sativum extracts on biofilm formation caused by S. mutans.
Materials and Methods: In this experimental study, the biofilm formation was carried out by broth dilution method with glucose -supplemented Tryptic Soy Agar (TSB) in 96-well microtiter plates. Seven serial dilutions from the aqueous extracts of the Punica granatum, Ricinus communis, and Allium sativum were prepared. Then, a suspension of S. mutans was added to the wells. The anti-biofilm effects of the extracts and turbidity were measured by an ELISA reader apparatus at OD₄₉₂nm. Experiments were completed in triplicate.
Findings: Ricinus communis was more active on S. mutans than other extracts. In comparison with others, the mean OD obtained in the presence of a concentration of 50mg of the plant extract (OD=0.083) was close to the negative control (OD=0.068). This plant was effective in higher concentrations (50, 25, 12.5 and 6.25mg/ml). Allium sativum extract has a moderate effect on S. mutans. The lowest activity belonged to Punica granatum extract.
Conclusion: The extract of Ricinus communis has strong anti-biofilm activity against Streptococcus mutans, when compared to other extracts, Allium sativum extract show moderate activity on the biofilm formation. Aqueous extract of Punica granatum peel isn’t very effective on S. mutans.

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Background: Staphylococcus epidermidis isolates are among the most important causes of nosocomial infections and could be classified as health threatening agents. This study aimed to determine the biofilm formation ability and clonal dissemination of S. epidermidis strains isolated from patients and healthy people in Isfahan during 2016 and 2017.
Materials & Methods: A total of 139 and 123 suspected colonies of S. epidermidis were collected from different clinical specimens and the arm of healthy people, respectively. The ability to form biofilm was determined using a combination of Congo-red agar (CRA) and microtiter plate (MTP) assays. The presence of genes involved in biofilm formation was also tested by the polymerase chain reaction (PCR) test. The susceptibility of all strains to 12 antibiotics was evaluated using the disk diffusion method according to the Clinical & Laboratory Standards Institute (CLSI) guidelines. Moreover, all biofilm-producing strains were typed using PhenePlate system as well as cassette chromosome mec (SCCmec) and accessory gene regulator (agr) locus typing method.
Findings: A total of 43 biofilm-producing S. epidermidis strains were identified among 107 and 123 confirmed strains isolated from hospitalized patients and healthy people, respectively; all of which were positive for aap gene, and the presence of ica operon was limited to 86 and 27% of the strains isolated from patients and healthy people, respectively. All the strains showed susceptibility to vancomycin, quinupristin-dalfopristin, and linezolid. Moreover, SCCmec Types III, IV, and V were detected among all methicillin-resistant S. epidermidis (MRSE) strains, and agr Type I was the most frequent one. Among all biofilm-positive strains, 3 common types (CTs) and 7 single types (STs) were determined;  CT1 and CT2 were the most common types among the strains isolated from hospitalized patients and healthy people.
Conclusion: These findings indicated the presence and persistence of diverse clone types of biofilm-producing S. epidermidis strains with common types of PhP, agr, and SCCmec in the hospital and the community of Isfahan.

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Backgrounds: Listeria monocytogenes is an opportunistic pathogen causing listeriosis, its pathogenicity is due to the presence of virulence factors including InlA, InlB, PlcA, PlcB, ActA, Iap, and Hly. The purpose of this study was to evaluate the formation of biofilm and its association with serotypes and virulence factors in L. monocytogenes isolates.
Material and Methods: In this study, 51 L. monocytogenes isolates were collected from blood, urine, feces, placenta, rectum, and vagina samples as well as livestock and food samples. Biofilm production was measured using microtiter plate assay, and virulence genes were identified by PCR method.
Findings: Out of 51 isolates, 27 (52.9%) were non-biofilm producers, 17 (33.3%) were weak biofilm producers, four (7.8%) were medium biofilm producers, and three (5.9%) were strong biofilm producers. According to this study results, different L. monocytogenes strains could form biofilm with various intensities. The actA, flaA, inlJ, inlA, and plcB genes were observed in all the isolates. The frequency of the hlyA, plcA, iap, inlB, and inlC genes among the isolates was 90.2, 94.1, 98, 88.2, and 82.4%, respectively. There was no significant correlation between the presence/absence of virulence genes in biofilm producing and non-biofilm forming isolates, except for the inlC and iap genes, which showed a significant correlation with the ability to form biofilm.
Conclusion: Due to the high prevalence rate of biofilm formation among the isolates and the importance of biofilm production in medical surfaces and food industries, eradication of biofilm-forming isolates is important.
 

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Backgrounds: Staphylococcus aureus is one of the major causes of nosocomial infections. Biofilm formation is an important virulence factor of S. aureus, leading to its high resistance to antibiotics and evasion from host defenses. This study aimed to assess the prevalence and antimicrobial resistance profile of biofilm-producing S. aureus strains and characterize genes involved in biofilm formation.
Materials & Methods: A total of 79 S. aureus strains were isolated from 1000 clinical samples and characterized using phenotypic, biochemical, and molecular tests. The biofilm production ability of isolates was examined using the microtiter assay. Moreover, the expression of genes involved in biofilm production (psm A and psm B) was screened using real-time PCR. Finally, antibiotic susceptibility testing was done using the Kirby-Bauer method and interpreted according to the CLSI M100 standard.
Findings: Out of 79 S. aureus isolates, 43 (54.4%) isolates were strong biofilm producers, 21 (26.6%) isolates were weak biofilm producers, and 15 (19%) isolates were non-adhesive. The results of real-time PCR showed that 55 (86%), 60 (93.7%), and 46 (58.2%) isolates were positive for psm A, psm B, and both genes, respectively. The results of antibiotic susceptibility testing showed that all the isolates were resistant to two or more antibiotics.
Conclusion: The high prevalence of biofilm-forming S. aureus strains in hospital environments could be a major health challenge with serious outcomes for hospitalized patients. Thus, it is necessary to disinfect hospital environments to reduce the risk of infection and spread of these microorganisms.
 

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Backgrounds: Uropathogenic Escherichia coli is a Gram-negative bacillus that is the most common cause of urinary tract infection. E. coli has the ability to produce biofilm as an important virulence factor. Due to the lack of sufficient information about ESBL resistance genes in this geographical area, this study aimed to investigate the prevalence of ESBLs in E. coli isolates to increase our knowledge about the role of these genes and biofilm formation in inducing resistance.
Materials & Methods: 139 E. coli strains were isolated from urine samples. Antibiotic susceptibility testing was performed for the isolates by disk diffusion method. ESBL production was confirmed using double-disk synergy test. Molecular detection of ESBL genes was performed using PCR. Biofilm formation assay was performed by microtiter plate method.
Findings: The most effective antibiotic against this bacterium was nitrofurantoin. Multidrug resistance was observed in 119 (85.6%) isolates. ESBL phenotype was detected in 93 (66.9%) isolates. The PCR test results showed that bla_CTX, bla_VEB, and bla_TEM were positive in 45 (32.4%), 87 (62.6%), and 10 (7.2%) isolates, respectively. The biofilm formation assay results revealed that 65 (46.8%), 58 (41.7%), 10 (7.2%), and six (4.3%) isolates were non-, weak, moderate, and strong biofilm producers, respectively.
Conclusions: The high prevalence of ESBL genes is a public health concern in this region because they could be transmitted to other susceptible bacteria and induce resistance. This study showed that biofilm production could increase antibiotic resistance.
 

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Backgrounds: The fungal pathogen Candida albicans is a cause of biofilm formation in patients with oropharyngeal candidiasis. Saccharomyces boulardii is a nonpathogenic fungal probiotic that plays an important role in preventing or treating intestinal diseases. This research aimed to determine the inhibitory effect of S. boulardii probiotic yeast on biofilm formation capacity of C. albicans, which is one of the main virulence factors.
Materials & Methods: In this study, 33 oropharyngeal samples were collected from patients with suspected oropharyngeal candidiasis (OPC). The inhibitory activity of S. boulardii against biofilm formation capacity of C. albicans was investigated by crystal violet-based staining (CVS) and MTT reduction reaction. The collected data were analyzed using student's t-test in SPSS statistical software.
Findings: In this study, the probiotic yeast S. boulardii reduced the pathogenicity and virulence of C. albicans in vitro. According to the results of CVS and MTT assays, a considerable reduction (p< .001) in the biomass and viability of C. albicans biofilms was observed after 48 hours of incubation in the presence of S. boulardii extract.
Conclusion: There was a significant association between S. boulardii extract concentration and biofilm formation in both CVS and MTT assays. Biofilm formation decreased with increasing S. boulardii extract concentration and incubation time in both methods compared to the control group.
 

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Background: Biofilm is described as an accumulation of microbial organisms connected to a living or unmoving surface mainly through self-secreted polymeric materials. With a complete understanding of biofilm behaviors and the role of rhamnolipids in its stability or dispersion, a new path could be designed in the treatment of infections like Pseudomonas aeruginosa (P. aeruginosa). The purpose of this study was to investigate the role and function of rhamnolipids in P. aeruginosa velocity and biofilm formation ability.
Materials & Methods: In this study, 68 P. aeruginosa clinical samples were isolated from February 2022 to 2023 and confirmed based on culture and molecular methods. The presence of genes associated with di-rhamnolipid (rhlC) and mono-rhamnolipid (rhlA and rhlB) biosynthesis was detected by PCR method. For velocity assay, bacterial cultures on Bushnell Haas medium were monitored for 24 and 72 hours (0.5%).
Findings: The results showed that the distribution of biofilm strength among P. aeruginosa strains was normal. The frequency of rhlC was significantly different from those of rhlA and rhlB (p= .01). In the first 24 hours, the velocity of P. aeruginosa on Bushnell Haas with glucose was 2 µm/min and decreased during 72 hours. But after 72 hours, the velocity of moderate and weak biofilm-producing strains on solid medium with glycerol was constant.
Conclusion: In this study, rhamnolipids produced from different carbon sources showed different behaviors on colony shape, velocity, and strength of bacterial biofilms.

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Aims: Recently, polymer-based nanofibrous scaffolds have attracted great attention due to their significant antibacterial properties in the field of dermatological applications. In this study, a polycaprolactone-based nanofibrous scaffold has been fabricated using the electrospinning method. The aim of this study was to evaluate the antibacterial effect of electrospun nanofibrous structures. Materials and Methods: In this experimental study, the structure and bacterial attachment on polymeric nanofibrous scaffolds were studied by Scanning Electron Microscopy (SEM). In addition, antibacterial properties of nanofibrous scaffolds were studied on two gram-negative bacteria of Escherichia coli and Pseudomonas aeruginosa and two gram-positive bacteria of Staphylococcus aureus and Streptococcus mutans, using microdilution method and biofilm assay. Moreover, MTT assay was performed on HeLa and human fibrosarcoma cell line (HT1080) cancerous cell lines to evaluate the cell viability.
Findings: The results of this study showed that nanofibrous scaffold revealed a significant antimicrobial and anti-biofilm formation effect on all of the studied bacterial strains, but in microscopic observations and microdilution assay was observed on Pseudomonas aeruginosa in 1mg/ml of nanofibrous scaffold extract concentration, while the major effect in biofilm assay was observed in 8µg/ml of extract concentration. Moreover, the cell viability studies showed that the most significant effect was shown on HT1080 cell line which has drastically decreased by 40% after 48 hours in comparison with the control.
Conclusion: These results show that electrospun nanofibrous PCL-based scaffolds are potentially promising for dermal tissue engineering applications, due to anti-biofilm effects and capability of reducing the number of cancerous cells in the wound site.

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Background: This study aimed to investigate the biofilm formation ability of K. pneumoniae clinical isolates using phenotypic and genotypic methods. Additionally, the association of biofilm formation with antibiotic resistance and the presence of biofilm-related genes was investigated.
Materials & Methods: In this research, a total of 52 clinical isolates of K. pneumoniae were collected from educational hospitals affiliated with Babol University of Medical Sciences from March to October 2023. K. pneumoniae isolates were identified through standard microbiological and biochemical tests. Disk diffusion, microtiter plate, and polymerase chain reaction assays were also performed to evaluate the biofilm formation ability of these isolates.
Findings: K. pneumoniae isolates were obtained from various clinical specimens. The isolates showed the highest resistance to ceftazidime (54%) and the lowest resistance to amikacin (17%). More than 48% of the isolates were multidrug resistant. Of the 52 K. pneumoniae isolates, 43 (82.69%) isolates produced biofilm, whereas the remaining nine (17.3%) did not. K. pneumoniae isolates harbored biofilm formation genes, including treC (78.84%), wcaG (71.15%), mrkD (65.38%), mrkA (63.46%), iutA (40.38%), and magA (15.38%).
Conclusion: This study demonstrates that K. pneumoniae isolates are highly pathogenic because of antibiotic resistance and carrying biofilm genes. Given the biofilm formation propensity of these strains, it is imperative to elucidate the underlying mechanisms of biofilm formation in K. pneumoniae. Developing strategies to inhibit this process is paramount in the effective management of infections caused by this pathogen.

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Background: This research aimed to assess the antibacterial and anti-biofilm properties of copper nanoparticles (CuNPs) produced using Artemisia biennis Willd through an eco-friendly approach, targeting four pathogenic bacteria.
Materials & Methods: A. biennis Willd extract with unit numbers “15.62-125” was prepared through maceration, drying, and powdering. Particle size distribution (PSD), dynamic light scattering (DLS), zeta potential, X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR) tests were used to characterize the synthesized CuNPs. Minimum inhibitory concentrations (MICs), minimum bactericidal concentrations (MBCs), and sub-minimum inhibitory concentrations (sub-MICs) were determined to investigate the antibacterial and anti-biofilm activities of CuNPs against Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, and Klebsiella pneumoniae ATCC 13883.
Findings:  CuNPs synthesized using A. biennis Willd extract exhibited a brown color change with particle sizes mainly 30-40 nm by PSD. DLS indicated uniform distribution and hydrodynamic synthesis of particles with a zeta potential of -37.8. XRD and FTIR confirmed copper nanoparticle biosynthesis. The MICs of CuNPs were 15.62-62.5 μg/mL, with S. aureus and K. pneumonia revealing the highest and lowest antimicrobial drug resistance, respectively. This trend was repeated for MBCs and sub-MICs, ranging from 15.62-125 and 7.8-31.25 μg/mL, respectively. Bacterial strains were unable to form biofilms at sub-MICs. The anti-biofilm effects of CuNPs were more significant on Gram-negative bacteria.
Conclusion: CuNPs synthesized using A. biennis Willd extract by a green method show promising anti-biofilm and antibacterial characteristics against bacteria, suggesting their potential for treating bacterial infections.
 

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In a marine environment, the biofilm formed on the submerged surfaces leads to fouling of larger organisms. This leads to many environmental and economic problems for the marine industries. Due to the harmful effects of chemical antifouling, the development of environmentally friendly anti-biofilm strategies can be an important step to control fouling.
Therefore, the present study was performed with the aim of isolation of biofilm-forming bacteria from Persian Gulf waters and investigating the antimicrobial effect of thymol against selected bacteria.82 bacterial were isolated and their ability to form biofilm was measured. Among these, 5 isolates were selected and identified using 16S rRNA sequences. The results showed that the 5 selected isolates belonged to the Proteobacteria (genus Vibrio, Kangiella and Psudoaltromonas). In the study of the antibacterial effect of thymol, K. spongicola (PH1) showed the highest sensitivity in disk diffusion method (with a growth inhibition zone diameter of 18 ± 0.57 mm). The minimum inhibitory concentration and minimum bactericidal concentration (at 31.5 and 62.5 μg /ml, respectively) were obtained against the same bacterium. The inhibitory thymol on biofilm formation and performed biofilm by Psudoaltromonas sp. (PH18) showed that thymol at concentrations sub-MIC is able to inhibit biofilm formation. The effect of thymol on the performed biofilm at concentrations higher than MIC is noticeable. Based on the results, due to the anti-biofilm activity of thymol against marine bacteria, its use as a natural compound in antifouling coatings can be suggested.

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Pseudomonas aeruginosa is one of the most important causes of infection in medicine, which in recent years is known as an antibiotic resistant bacterium. One of the antibiotic resistance strategies of this bacterium is algD and PpyR genes expression for biofilm formation.

 In recent years, it has been shown that using microorganisms, such as probiotics, is a method of pathogen bacterium harnessing, hence, in this study, for preventing biofilm formation of P. aeruginosa, E.coli Nissle 1917(EcN) probiotic bacterium is used, as a new treatment choice.

Due to direct relationship between antibiotic resistance and biofilm formation, strains with the    

highest antibiotic resistance was chosen by antibiogram test. Then, in order to determine the inhibition rate of EcN bacterium in the formation of biofilm caused by P. aeruginosa bacterium, a biofilm formation test was performed.

At the end, to evaluate algD and PpyR genes expression, which were key parts of biofilm formation, in the presence of probiotic EcN bacterium, Real- time PCR method was used.

Based on the results of the biofilm formation test, EcN bacterium showed a high inhibitory effect on the formation of biofilm caused by P. aeruginosa bacterium.

.Also, in assessment of algD and PpyR genes expression in presence of EcN probiotic, a significant reduction in PpyR gene expression has been seen, in comparison with control group. The results of this study showed that EcN probiotic can act as a suitable new treatment option, to reduce P. aeruginosa biofilm formation.

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The composition of wastwwater in sewer lines are changing due to their nature. Wastewater contains large amount of organic materials, therfore it is suseptible to biological disintegritaion. Normally the conditions of sewers dicctate and promote the type of growth of bacteria being either aerobic or anaerobic. Previous studies have shown that large number of concrete sewer lines were found to beeffected by anaerobic bacteria activites. In this experimental investigation the aerobic biological transformation of organic matter in small diameter gravity slope wastewater collection system is evaluated. In this study a sewer network reactor at pilot scale was designed and built. The reactor consists of 15 meters length of PVC with 0.1 m diameter, two storage tanks and re circulating pump. The whole system was set up on a platform with adjustable slope. To ease the Formation of attached growth of micro organism a plastic net was attached on the inner surface of PVC pipe, thus a rough surface for attachment of microorganisms was formed. Due to the variation of hydraulic mean diameter, contact area with flowing wastewater was ranged from 1.88 to 3.77 m2 (half or full). Synthetic wastewater with characteristic municipal wastewater was used. A settled activated sludge fromYasreb wastewater treatment plant in Qaemshahr city was used to start and accelerate the biofilm growth in the reactor. In order to study bio-film attachment rate two P.V.C square plates in dimensions of 10*10 cm were placed perpendicular on the direction flow of wastewater. The reactor was conducted under aerobic conditions in a hydraulic retention time of 7 hours under constant temperature changed about 20 ±3 C. In this study parameter such as BOD, COD, TN and NH3-N and NO3-N were measured on daily basis. The thickness of biofilm increased and formed as irregular with thickness of 3-4.7 mm. Biofilm characteristics analysis showed that density and surface density were respectively 55 mg Ts/cm-3 and between 22.3 and 33.1 m-2. The concentration of suspended biomass was varied from10-15 mgl-1 at optimum COD removal. Oxygen consumption rate was estimated from decreasing rate of soluble oxygen concentration which reached to 0.21 mg l-1 min-1 after 3 weeks of operation. The highest reduction in COD and biological oxygen demand (BOD) concentration were 59% and 54% respectively . By increasing the chemichal oxygen demand (COD) loading by 70 %, removal rate of COD reduced by only 9%. Due to high COD concentration of wastewater effuluent, the nitrification process was limited. In order to nitrify the waste water, a longer hydraulic retention time(HRT) or higher recirculation is required. From the results and analysis it can seen be seen that proposed innovative method is applicable in many fields such as mountainous area, area with water stress ratio, water scarce area and ... which normally an application of conventional wastewater treatment either are costly or impractical. And also with regard to publicized incentives for using waste water reclaimation as a source of water for agricultral irrigation, thus with more precision in desigin and operation, an effluent of these new configuration of PVC pipes can be used in agri-industry

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Objective: Acinetobacter baumannii (A. baumannii) is a major hospital pathogen with a high capacity to resist most common anti-microbial agents. A. baumannii is the etiologic agent for various illnesses including pneumonia, meningitis, and bloodstream infections. Biofilm associated proteins (Bap) are specific cell surface proteins essential for the formation of biofilm and play a main role in its pathogenicity. Previously, we have studied various regions of this protein. Considering different criteria, some regions were introduced as conserved and immunogenic. The immunogenicity of one of those regions pertaining to amino acids 706-1076 previously examined has shown that its expression triggers high antibody levels when injected to mice thereby protecting the animals against the bacterium. The present study examines region 4 of the Bap protein in order to validate the previous bioinformatics studies and its immunogenicity. Methods: In order to obtain immunity against this pathogen, a 1620 bp gene from Bap was amplified and cloned in pET32a. This region from Bap was cloned, expressed and verified by monoclonal antibodies. BALB/c mice were immunized by subcutaneous injection of the pure recombinant protein. Mice immune response was determined by ELISA. Results: High titer of raised antibodies implied that the recombinant protein was a strong antigen and immunogen. Conclusion: The results indicate that this protein can be a suitable choice for developing a new recombinant vaccine against A. baumannii.

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Tooth decay is one of the most common problems in the world, which is caused by the growth of biofilm and acid production by them. Many solutions have been used to solve this problem. However, due to the increase in antibiotic resistance of microorganisms and the increasing need for antimicrobial substances, efforts are being made to use natural antimicrobial substances. Lactoferrin is a protein in milk and saliva with antimicrobial and anti-biofilm properties. In this research, lactoferrin was encapsulated by nanoliposomes to increase its antimicrobial properties. In order to measure the effect of lactoferrin on the number of bacteria in the polymicrobial biofilm and acid production, each of the free substances or nanoliposomes in 4 concentrations (0, 1.5, 3, 6 mg/ml) in the Active Attachment biofilm model with saliva and culture medium was incubated.
The results showed that lactoferrin nanocoating increased the ability to inhibit biofilm and acid production by this bacterium due to the slow release of lactoferrin from liposomes. When increasing the concentration of free and nanoliposomal lactoferrin to a concentration of 3 mg/ml, a significant decrease in the number of bacteria in the biofilm was observed compared to the control sample (P<0.01). However, increasing the concentration of free lactoferrin again increased the number of bacteria in the biofilm. Meanwhile, nanoliposomal lactoferrin at a concentration of 6 mg/ml still caused a decrease in bacteria in the biofilm, which was insignificant compared to the concentration of 3 mg/ml (P>0.01). From the obtained results, it can be concluded that nanoliposomal lactoferrin can be used to design products related to oral and dental health.
 

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The presence of methicillin-resistant (MRSA) and vancomycin-resistant (VRSA) Staphylococcus aureus in food raises a public health concern. This study aimed to investigate the antibacterial and anti-biofilm activity of some Lamiaceae essential oils including Melissa Officinalis, Salvia officinalis, and Mentha piperita against MRSA and for the first time on VRSA strains. For this purpose, the disk diffusion test, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), minimum biofilm inhibitory concentration (MBIC), and minimum biofilm eradication concentration (MBEC) were determined. Then, M. Officinalis essential oil compounds were investigated against PBP2a, agrA, and Bap proteins using AutoDocK Vina. Finally, pharmacokinetic properties were investigated using ADMETsar and SwissADME servers. Based on the obtained results, the MIC and MBC values of M. Officinalis essential oil against MRSA strain were equal to 0.05 and 0.112 mg/ml, and against VRSA strain were equal to 1.8 and 2.5 mg/ml, respectively. The MBIC and MBEC of M. Officinalis essential oil against MRSA strain were equal to 0.03 mg/ml and 0.112 mg/ml, and against VRSA strain were equal to 0.9 mg/ml and 3.2 mg/ml, respectively. The results of molecular docking showed that β-Caryophyllene had a greater binding affinity to PBP2a protein either in the active site or in the allosteric site (-6.6kcal/mol). On the other hand, the effective compounds of this essential oil, especially citronellol, thymol, and citral, were acceptable in terms of pharmacokinetic properties. Since natural antibiotics can be an alternative to conventional antibiotics in the treatment of Staphylococcus aureus food-borne diseases, the results of this study showed that Melissa Officinalis essential oil is effective on the growth and biofilm of MRSA and VRSA strains, and it can be used as a drug candidate in the prevention and treatment of infections caused by antibiotic-resistant strains of this bacterium.