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2023 CiteScore: 2.4
pISSN: 2008-3289
eISSN: 2008-4447
Chairman and Editor-in-Chief:
Mohammad Mehdi Feizabadi
This journal is a member of, and subscribes to the principles of, the Committee on Publication Ethics (COPE).
Vol 8 No 1 (2016)
Articles
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Background and Objectives: Due to the importance of finding of new antibacterial agents, the antibacterial properties of Prosopis cineraria aerial parts were investigated using a bioassay guided fractionation scheme.
Materials and Methods: The organic extract was prepared via maceration in methanol, followed by the fractionation using n-hexane and ethyl acetate. The MICs of fractions were determined against some human pathogenic bacteria using broth micro-dilution assay. The primary characterization and identification of bioactive substance(s) was based on a bio-autograph- ical method using HPTLC and flash chromatography in parallel with agar overlay assays. Finally the exact mass of effective compound(s) was determined by LC-MS.
Results: The best antibacterial activities were related to the ethyl acetate fraction. The effective antibacterial compound of the plant were 2 substances with molecular weight of 348 and 184 Dalton that inhibited the growth of assessed Gram positive bacteria with MIC values lower than 125 to 62.5 µg/ml synergistically.
Conclusion: Further analysis using nuclear magnetic resonance could reveal the exact structure of these two antibacterial substances. These 2 effective antibacterial compounds could be applied as lead compound for synthesis of new antibacterial agents. -
Background and Objectives: Proteases are a group of enzymes that catalyze the degradation of proteins resulting in the pro- duction of their amino acid constituents. They are the most important group of industrial enzymes which account for about 60% of total enzymes in the market and produced mainly by microorganisms. The attempts were made to study the kinetic parameters of protease produced by Streptomyces griseoflavus PTCC1130.
Materials and Methods: Streptomyces griseoflavus PTCC1130 was grown on casein agar. Different media such as BM1, BM2, BM3 and BM4 were prepared. Data obtained from growth and protease production were subjected to kinetics evalu- ation. Casein was used as substrate for protease activity and the released soluble peptide bearing aromatic amino acid were quantified by Folin Cioclateaue reagent. Protein content of the enzyme and the sugar utilized by the organism were estimated by Bradford and Miller’s methods respectively.
Results: Basal Medium named as BM1, BM2, BM3 and BM4(50 mL in 250 mL Erlen Meyer flasks) were screened out to evaluate protease production by Streptomyces griseoflavus PTCC1130. They were inoculated with known amount of seed culture and kept on rotary shaker. To obtain the specific growth rate, wet weight of biomass was plotted against the time. The clarified supernatant was used for the analysis of protease by measuring the soluble peptide containing aromatic amino acid residues employing Folin Cioclateaue reagent. Our results showed that maximum level of enzyme production (14035 U/L) was occurred at late exponential phase using Basal Medium supplemented with zinc sulfate (0.5g/L), casein (10g/L) at pH 6.5.
Conclusions: A kinetic study of protease production by Streptomyces griseoflavus PTCC1130 provided highly quantitative information regarding the behavior of a system, which is essential to study the fermentation process. Exploitation of such kinetics analysis would be useful in commercialization of microbial enzyme production. -
Background and Objectives: Tannins are toxic polyphenols that either bind and precipitate or condense proteins. The high tannin content of some plants is the preliminary limitation of using them as a ruminant feed. So, the aim of this study was the isolation and characterization of tannic acid degrading bacterial strains from goat feces before and after feeding on Pis- tachio-Soft Hulls as tannin rich diet (TRD).
Materials and Methods: Bacterial strains capable of utilizing tannic acid as sole carbon and energy source were isolated and characterized from goat feces before and after feeding on TRD. Tannase activity, maximum tolerable concentration and biodegradation potential were assessed.
Results: Four tannase positive isolates were identified as Klebsiella pneumoniae. Isolated strains showed the maximum tolerable concentration of 64g/L of tannin. The tannic acid degradation percentage at a concentration of 15.0 g/L reached a maximum of 68% after 24 h incubation, and more than 98% after 72 h incubation. The pH of the medium also decreased along with tannic acid utilization.
Conclusions: It is obvious that TRD induced adaptive responses. Thus, while the bacteria were able to degrade and detoxify the tannic acids, they had to adapt in the presence of high concentrations of tannic acid. So, these isolates have an amazing potential for application in bioremediation, waste water treatment, also reduction of tannins antinutritional effects in animal feeds. -
Background and Objectives: During past decades Hansenula polymorpha has attracted global attention for the expression of recombinant proteins due to its high growth rate, minimal nutritional porequirements and use of methanol as a low cost inducer.
Materials and Methods: The corresponding nucleotide sequences for the expression of heterologous genes in Hansenula poylmorpha were extracted and assembled in an E. coli vector. The constructed expression cassette included formate dehy- drogenase promoter (pFMD), a secretory signal sequence, a multiple cloning site (MCS) and methanol oxidase (MOX) ter- minator. Zeocin resistance gene fragment and complete cDNA encoding granulocyte colony stimulating factor (GCSF) were cloned downstream of the expression cassette in-frame with signal sequence. Restriction mapping and sequence analysis confirmed the correct cloning procedures. Final vector was transformed into Hansenula and recombinant host was induced for the expression of GCSF protein by adding methanol. SDS-PAGE and immuno-blotting were performed to confirm the identity of r-GCSF.
Results: The expression cassette containing gcsf gene (615bp) and zeocin resistance marker (sh-ble, 1200bp) was prepared and successfully transformed into competent Hansenula polymorpha cells via electroporation. Zeocin resistant colonies were selected and GCSF expression was induced in recombinant Hansenula transformants using 0.5% methanol and an approx- imately 19kDa protein was observed on SDS-PAGE. Western blot analysis using serum isolated from GCSF-treated rabbit confirmed the identity of the protein.
Conclusions: Molecular studies confirmed the designed expression cassette containing gcsf gene along with pFMD and sig- nal sequence. The expressed 19kDa protein also confirmed the ability of designed vector in expressing heterologous genes in Hansenula cells. -
Background and Objective: Neisseria meningitidis is a leading cause of meningitis and sepsis worldwide. The factor H binding protein (fHBP) is a key virulence factor of Neisseria meningitidis that is able to selectively bind to human factor H, the key regulator of the alternative complement pathway, which it has important implications for meningococcal pathogene- sis and vaccine design. The aims of present research were cloning, expression, purification of fHbp and confirmation of the interaction between serum factor H (fH) and produced factor H binding protein.
Materials and Methods: A 820 base pairs fhbp gene fragment was amplified by PCR and cloned into expression vector pE- T28a (+) in Bam HI and SalI restriction enzymes sites. Recombinant DNA was expressed in BL21 (DE3) cell. fHBP protein was purified by Ni-NTA agarose resin. Coupling of recombinant protein into CNBr activated Sepharose 4B resin was carried out for application in serum fH protein purification. (fH-fHBP) interaction was confirmed by SDS-PAGE and far-western blotting.
Results and Conclusions: SDS-PAGE results showed a 35 kDa protein band. 150 kDa fH protein was purified by designed Sepharose 4B resin. Far-western blotting confirmed (fH-fHBP) interaction and proper folding of factor H binding protein. -
Antifungal susceptibility and virulence factors of clinically isolated dermatophytes in Tehran, Iran
Background and Objectives: Dermatophytes possess a wide array of virulence factors and various antifungal susceptibility patterns which influence their pathogenesis in humans and animals. The aim of this study was to evaluate antifungal suscep- tibility and keratinase and proteinase activity of 49 dermatophyte strains from the genera Microsporum, Trichophyton and Epidermophyton which were isolated from human cases of dermatophytosis.
Materials and Methods: Forty-nine dermatophyte strains isolated from clinical samples were cultured on general and spe- cific culture media. Keratinase and proteinase activity was screened on solid mineral media and confirmed in liquid cultures. Drug susceptibility toward azoles (fluconazole, ketoconazole and itraconazole), griseofulvin and terbinafine was evaluated using disk diffusion method on Mueller-Hinton agar and minimum inhibitory concentrations (MICs) were determined using microbroth dilution assay according to the Clinical and Laboratory Standards Institute (CLSI) guidelines.
Results: Our results indicated that clinically isolated dermatophytes from 7 major species produced keratinase and protein- ase at different extents. The mean keratinase and proteinase activity was reported as 6.69 ± 0.31 (U/ml) and 2.10 ± 0.22 (U/ ml) respectively. Disk diffusion and microbroth dilution (MIC) results of antifungal susceptibility testing showed that ke- toconazole was the most effective drug against Epidermophyton floccosum and Trichophyton mentagrophytes, itraconazole against T. rubrum and E. floccosum, and griseofulvin and terbinafine against Trichophyton verrucosum. Our results showed that all dermatophyte isolates were resistant to fluconazole. Overall, ketoconazole and itraconazole were the most effective drugs for all dermatophyte species tested.
Conclusion: Our results showed that antifungal susceptibility testing is an urgent need to select drugs of choice for treatment of different types of dermatophytosis and further indicated the importance of keratinase and proteinase in pathogenesis of dermatophyte species. -
Background and Objectives: Unhygienic poultry feedstuffs can lead to nutrient losses and detrimental effect on poultry production and public health. In the present study, mycobiota and colony-forming units per gram in ingredients and finish poultry feed was evaluated with special reference to potentially mycotoxigenic fungi.
Materials and Methods: Eighty five samples of corn, soybean meal and poultry finished feed were collected from nine poultry feed factories located in three provinces i.e. Tehran, Alborz and Qom in Iran from October 2014 to January 2015. Samples were cultured on Sabouraud dextrose agar (SDA), Aspergillus flavus and parasiticus agar (AFPA) and dichloran rosebengal chloramphenicol agar (DRBC) and incubated at 28 ºC for 7-10 days. Purified fungal colonies were identified by a combination of macro- and microscopic morphological criteria. For determining the rate of fungal contamination, samples were cultured on SDA and colony forming units (CFUs) were calculated.
Results: A total of 384 fungal isolates belonging to 7 genera of filamentous fungi and yeasts were obtained from corn (124 isolates), soybean meal (92 isolates), and feed before (72 isolates), and after pelleting (96 isolates). The most prominent fungal isolate in corn, soybean meal and feed before pelleting (feed as mash form) was Fusarium but in feed after pelleting was Aspergillus. Among 5 Aspergillus species isolated, potentially aflatoxigenic A. flavus isolates was predominant in corn (46.6%), soybean meal (72.7%) and poultry finished feed (75%). CFUs results indicated that 9/22 corn samples (40.9%), none of 22 soybean meal samples, 19/41 finished feed (46.3%) were contaminated higher than the standard limit.
Conclusions: Our results indicated that corn, soybean meal and finished feed of poultry feed mill are contaminated with various fungal genera by different levels sometimes higher that the standard limits. Contamination with potentially myco- toxigenic fungi especially Aspergillus species may be considered as a human public health hazard. -
Background and Objectives: Klebsiella pneumoniae, one of the important causes of nosocomial infections, is the most common extended spectrum β-lactamases (ESBLs) producing organism. ESBLs are defined as the enzymes capable of hydrolyzing oxyimino-cephalosporins, monobactams and carbapenems. The aims of this study were to identify ESBL-producing K. pneumoniae isolates and detect their antibiotic susceptibility pattern.
Materials and Methods: This cross-sectional study was conducted from December 2012 to May 2013 in teaching hospitals in Shiraz. Clinical specimens from the urine, sputum, wound, blood, throat, and body fluids were isolated and identified as K. pneumoniae. Antibacterial susceptibility testing was performed for 14 antibiotics using disk diffusion method according to CLSI guidelines. Isolates showing resistant to at least one of the β-lactam antibiotics were then evaluated for production of β-lactamase enzymes using E-test ESBL and combined disk Method. Also, MICs for ceftazidime and imipenem were determined using E-test. The presence of the blaSHV, blaTEM٫ blaPER and blaCTX-M genes was assessed by PCR.
Results: Of 144 K. pneumoniae isolates from different specimens, 38 (26.3 %) was identified as ESBL producer by phenotypic confirmatory test. All ESBL producing isolates were susceptible to imipenem and meropenem and resistant to aztreonam. The highest rate of resistance belonged to amoxicillin (100%), cefotaxime (50%) and gentamicin (42.3%) and the lowest rates were seen for meropenem (11.8%), imipenem and amikacin (both 15.9%). Sixty-two isolates had MICs≥ 4 μg/ mL for ceftazidime, of which 38 were positive for ESBLs in phenotypic confirmatory tests (PCT). The prevalence of blaSHV, blaCTX-M, and blaTEM genes among these isolates were 22.2%, 19% and 16%. blaPER was not detected in the studied isolates.
Conclusions: Due to the relatively high prevalence of ESBLs-producing K. pneumoniae isolates in the studied population, it seems that screening of infections caused by ESBL producers can lead to the most effective antibiotics therapies. -
Background and Objectives: The prevalence of multidrug resistant Pseudomonas aeruginosa is the main reason of new drugs resurgence such as colistin. The main objectives of this study were to determine the antibiotic resistance pattern and the rate of colistin resistance along with its correlation with overexpression of MexAB-OprM and MexXY-OprM efflux pumps among P. aeruginosa isolates.
Materials and Methods: Hundred clinical isolates were collected from 100 patients during 6 months in 2014. Susceptibility to the eight antibiotics was investigated using Kirby-Bauer and agar dilution methods. The Quantitative Real-time PCR was used to determine the expression levels of efflux genes.
Results: Resistance rates to various antibiotics were as follows: ticarcillin (73%), ciprofloxacin (65%), aztreonam (60%), ceftazidime (55%), gentamicin (55%), imipenem (49%), piperacillin/tazobactam (34%) and colistin (2%). In disk diffusion method, only two isolates were non susceptible to colistin, however in agar dilution method the two isolates were confirmed as resistant and two others were intermediate resistant. Sixty eight (68%) isolates were multi-drug resistant and 10 isolates were susceptible to all tested antibiotics. Both colistin resistant isolates showed overexpression of both efflux pumps, but two intermediate resistant isolates exhibited reduction of efflux genes expression.
Conclusions: Emergence of colistin resistance is increasing in P. aeruginosa indicating great challenge in the treatment of infections caused by MDR strains of this organism in Iran. ParRS may promote either induced or constitutive resistance to colistin through the activation of distinct mechanisms such as MDR efflux pumps, and LPS modification. -
Morganella morganii is rarely isolated from nosocomial infections. However, postoperative infections due to Morganella spp. were documented in literature and eye involvements of the infections usually result in severe sequels. We present a severe case infection, which was caused by M. morganii subsp. morganii, firstly appearing as conjunctivitis and complicated by bacteremia. The infectious agent isolated from both conjunctival and consecutive blood cultures. Identification and anti- microbial susceptibility tests were performed with the Vitek 2® automated system. The isolate was resistant to cephalosporins and carbapenems and it had ability to produce extended spectrum beta-lactamases. Patient was successfully treated with intravenous ciprofloxacin according to susceptibility test results. This is the first report of M. morganii infection detected as a local infection then complicated by bacteremia.
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Background and Objectives: Streptococcus agalactiae is the leading cause of bacterial sepsis and meningitis in newborns and results in pneumonia and bacteremia in adults. A number of S. agalactiae components are involved in colonization of target cells. Destruction of peptidoglycan and division of covalently linked daughter cells is mediated by autolysins. In this study, autolytic activity and plasma binding ability of AFb novel recombinant protein of S. agalactiae was investigated.
Materials and Methods: The gbs1805 gene was cloned and expressed. E. coli strains DH5α and BL21 were used as cloning and expression hosts, respectively. After purification, antigenicity and binding ability to plasma proteins of the recombinant protein was evaluated.
Results: AFb, the 18KDa protein was purified successfully. The insoluble mature protein revealed the ability to bind to fibrinogen and fibronectin. This insoluble mature protein revealed that it has the ability to bind to fibrinogen and fibronectin plasma proteins. Furthermore, in silico analysis demonstrated the AFb has an autolytic activity.
Conclusions: AFb is a novel protein capable of binding to fibrinogen and fibronectin. This findings lay a ground work for further investigation of the role of the bacteria in adhesion and colonization to the host. -
Background and Objectives: Human bocavirus (HBoV) is a newly discovered parvovirus. It has been detected primarily in children with acute respiratory tract infections. This study was conducted to clarify the frequency and genotype circulation pattern of HBoV in Iran.
Materials and Methods: Conventional PCR was performed on throat swabs of patients less than two years of age with respiratory illnesses during fall and winter 2012-2013.
Results: HBoV virus DNA was detected in 15 of 140 samples (10.7 %). Sequencing and phylogenetic analysis on 5 samples showed that all were HBoV1. The positive samples were negative for influenza A and B viruses while co-infection with RSV was found in 2 (13.3%).
Conclusion: This study adds to the body of knowledge about the role of HBoV in acute respiratory illnesses in children in Iran.
