فصلنامه دنیای میکروب ها
سال دوازدهم شماره 1 (پیاپی 38، بهار 1398)

Liver cirrhosis is one of the most important causes of the need for liver transplantation. Several factors such as viral infections, autoimmune diseases, taking medication, hereditary diseases, genetic background, and also alcohol consumption are the causes of liver cirrhosis. The aim of this study was to optimize an accurate method in order to determine the rate of MMP-2 gene expression as a criterion in the evaluation of development and exacerbation of liver cirrhosis.   In this study 33 of 258 liver cirrhotic patients after approving the lack of presence of viral hepatitis C and B infections were evaluated with 20 healthy people as control. The rate of MMP-2 gene mRNA expression was appraised and optimized using Real-time PCR technique. Afterward, two patient and control groups were compared in terms of the MMP-2 gene expression.   The evaluation of mRNA expression disclosed significant increase of MMP-2 gene in patients group in comparison to control group.   Outcomes of the research highlighted that non-viral agents of chronic liver diseases could have an influence on increasing the level of MMP-2 gene expression and liver cirrhosis exacerbation; however, to confirm the above-mentioned results further studies are required.

Members of Acinetobacter genus are normal flora and the causal agent of the opportunistic nosocomial infections. The aim of this study was to investigate the ability to acquire drug resistance through efflux pump mechanism in multidrug-resistant Acinetobacter spp. and the role of PAβN (Phenyl Arginin β naphtyamid) as an efflux pump inhibitor.    In the cross-sectional descriptive study 83 clinical isolates and 62 environmental isolates were collected. Identification of the isolated bacteria was carried out by standard biochemical experiments and polymerase chain reaction (PCR) using specific primers of 16S rRNA and 16S-23S rRNA. Antibiotic susceptibility tests were conducted through disc diffusion and MIC test based on CLSI guidelines. The activity of the efflux pump was evaluated using the PaβN, and the adeABC gene frequency was assessed by PCR.   Of the total of the samples evaluated, 56 (67.47%) clinical isolates and 34 (54.84%) environmental isolates were identified as Acinetobacter spp. In accordance with the results of the antibiogram test, 100% of the isolates were resistant to cefotaxime and ceftriaxone. Only 7.13% of the clinical isolates and 5.89% of the environmental isolates were not multidrug-resistant (MDR). Prevalence of the adeB was 69.60%, 82.14%, and 76.80% in the clinical isolates and 50%, 85.30%, and 73.50% in the environmental isolates, respectively. Furthermore, tetracycline MIC was decreased in all resistant isolates in the presence of PAβN.   The results showed that the efflux pump could play a role in antibiotic resistance in Acinetobacter spp. isolates. Owing to the resistance of Acinetobacter isolates against cephalosporine, it is suggested to avoid prescribing.

Owing to the antimicrobial activity of ZnO nanoparticles without causing resistance, such substances could be considered as an appropriate alternative to prevent bacterial biofilm formation. The aim of this study was to the biosynthesis of ZnO nanoparticles using green tea extract and determination of its effect on biofilm formation in Pseudomonas aeruginosa isolates separated from wound infection.   In this cross-sectional study, biosynthetic nanoparticles were evaluated by X-ray diffraction, energy dispersive X-ray analysis, scanning electron microscopy and transmission electron microscopy. Determination of antimicrobial activity and minimum inhibitory concentration of nanoparticles were done by micro broth dilution method. The antibiofilm activity was investigated using biofilm formation by O'Toole 2011 method.   The biosynthesis of nanoparticles was confirmed by analysis. The size of the nanoparticles was determined in the range of 10 to 90 with an average of less than 40 nm. The nanoparticles had anti-microbial activities in concentrations of 250, 500 and 1000 ug/mL and minimum inhibitory concentration of 500 ug/mL was reported. The antimicrobial and antibiofilm effects of the nanoparticles rose with increasing the concentrations.   The biosynthesis of nanoparticles with the extract has a variety of benefits such as simplicity, good stability, without energy consumption, less time-consuming, non-toxic wastes, economical efficiency, and large scale synthesis capability. According to the antimicrobial and antibiofilm properties, the use of these nanoparticles as coatings in medical equipment and food industries is recommended.

Yeasts have a special value for human in biotechnology because of the production of pigments. Rhodotorula species produce high amounts of beta-carotene. The aim of this study was to maximize the production of beta-carotene at least prices from native yeast species.   The four isolation evaluated were isolated from specific environments during three stages of sampling from the waste leather factory.  Subsequently, two isolates of Aa1 and Aa4 were identified using the biochemical test and PCR technique. The production of beta-carotene was determined by the identified isolates and a standard strain in different conditions of salt, nitrogen source, carbon source, aeration, temperature, and pH. Optical absorption of the pigment was read through spectrophotometer at 470 nm.   Among the four isolates, only the isolate Aa1 is capable to produce carton-free pigment. The genetic identification of the two isolates Aa1 and Aa4 confirmed 98% similarity to those of Rhodotorula mucilaginosa and Debaryomyces hanseni, respectively. The results showed that the maximum production of beta-carotene was obtained after optimization of 75.6 μg/ml for Rhodotorula mucilaginosa and 32.7 μg/ml for Rhodotorula glutinis (standard strain).   The isolation of native species and the optimization of its functional activities in the laboratory is not only useful in the production of high-quality industrial products, but also the use of the native species is highly economical.

Fusarium graminearum is the causal agent of scab disease in wheat and other small grains. Zearalenone and deoxynivalenol are the main toxins produced by F. graminearum. In this study, the effects of essential oils of Elettaria cardamomum, Pistacia atlantica, and Eugenia caryophillata on F. graminearum growth inhibition and the expression of some genes in deoxynivalenol biosynthetic pathway were investigated.   Minimal inhibitory concentration (MIC) of the fungal growth was measured through the microtiter plate method after growing F. graminearum on Potato Dextrose Broth. In addition, the expression of TRI5, TRI6, and TRI14 genes were evaluated using real-time PCR (qRT-PCR) technique.   Elettaria cardamomum essential oil had the lowest MIC (100 µl/ml) and the essential oils of P. atlantica and E. caryophillata had the highest MIC (200 µl/ml). Elettaria cardamomum essential oil had the lowest MFC (200 µl/ml) and the highest fungicidal property against  F. graminearum, and the essential oils of P. atlantica and E. caryophillata had the highest MFC value (400 µl/ml). The expression of TRI5, TRI6, and TRI14 genes was significantly decreased by E. cardamomum essential oil.   The results of the study showed that the E. cardamomum essential oil has fungicidal and inhibitory effects against F. graminearum and leads to reduce the expression of TRI5, TRI6, and TRI14 genes relating to deoxynivalenol production.

Crude oil contains significant amounts of heavy metals which could lead to soil contamination. The aim of this study is to evaluate the function of rhomnolipid biosurfactant in the removal of heavy metals (nickel, chromium, and cadmium) from soil contaminated with crude oil.   In the cross-sectional descriptive study, rhamnolipid biosurfactant was firstly produced from Pseudomonas aeruginosa PTCC1340 and then confirmed through TLC and FTIR experiments. In the next step, sandy soil was sieved at 2 mm and placed in a beaker for contamination with crude oil (API: 32.83, Viscosity: 6.21cp). The contaminated soil was washed with rhamnolipid solution (1:10 ratio) for 24 h in falcon tubes under different conditions such as temperature, pH and concentration. Subsequently, the solution containing the heavy metals was acid digested to release the metals in the form of ion. Finally, the amount of the heavy metals removed by rhamnolipid biosurfactant was measured using atomic absorption spectrophotometer.   The removal amount of heavy metals from soil contamination at an optimum condition (temperature: 25 ◦C, concentration: 0.8 g/l and pH 11) to nickel, chromium, and cadmium was 43.05%, 34.73%, and 52.81%, respectively.   Washing the soil with produced biosurfactant gives rise to the removal of heavy metals without having detrimental effects of the chemical surfactants and subsequently reduces the environmental hazards. In accordance with the outcomes of the research, the method is highly suggested to industries to eliminate the heavy metals from crude oil using biosurfactants.

Staphylococcus aureus is an opportunistic pathogen and one of the most important health-threatening agents worldwide. Expression of bacterial virulence factors is not similar in laboratory medium conditions and in vivo. The aim of the present study was to evaluate the effects of adding 5% calf serum on the virulence genes expression of S. aureus.   The expression levels of agrA, RNAIII, hla, spa, and mecA genes were     determined during the growth of S. aureus isolates in BHI broth and BHI broth enriching with calf serum during different growth phases. Therefore, the growth curve of the five isolates of S. aureus in two different culture conditions was plotted. Subsequently, RNA was extracted from different phases of growth and the genes expression were analyzed by Real-time PCR.   In average, the expression levels of agrA and RNAIII from stationary phase to the exponential phase in BHI broth containing calf serum was increased 3.4 and 9.5-fold, respectively, while the agr system could not appropriately play its regulatory role in the expression of virulence genes. As a result, the expression of hla gene was decreased 0.81-fold and the expression levels of spa and mecA genes was only increased 1.25 and 1.03-fold, respectively.   Regardless of the growth phase, the expression of the whole genes in BHI broth containing calf serum were increased in comparison to BHI broth. Consequently, it appears that S. aureus is capable to induce virulence genes expression in the presence of calf serum factors similar to conditions available in vivo.

Glutathione-S-transferase (GST) are a group of enzymes found in all living organisms that contribute to detoxification of xenobiotic compounds via Phase II conjugation with glutathione and play an important role in drug resistance. The GST activity in chloroquine-resistant strains of rodent and human Plasmodium is meaningfully higher than sensitive strains. In the present study, the GST activity and level were measured in those mice infected with Plasmodium berghei during the treatment with antimalarial drugs. Mice infections were carried out by P. berghei and inhibition growth of the parasite was performed through three doses of eosin B and prevalent antimalarial drugs similarly artemisinin and sulfadoxine-pyrimethamine in 24 h based on Peter's test. Two hours after the last dose, the mice were bled, RBCs were isolated by cellulose column, and P. berghei was released after washing with saponin. The enzyme function was measured using glutathione and CDNB as substrate at 340 nm. In addition, the GST levels were assessed by Biotech kit. The GST specific activities and levels of P. berghei in infected mice treated with eosin B and sulfadoxine-pyrimethamine and their combination were decreased while such change was not seen in those ones treated with atemisinin and in combination with eosin B. Owing to the reduction property of the combination of eosin B on the GST which has a fundamental role in the resistance of the parasite to antimalarial drugs, it could be considered as a promising procedure for application in antimalarial combination drugs.