Showing 5 results for Zarali
Volume 13, Issue 52 (4-2016)
Abstract
The aim of this study was to investigate the antibacterial activities of Echinophora cinerea and Stachys lavandulifolia Vahl essential oils cultivated in Lorestan province against some food pathogens. The aerial parts of these plants were collected from the mountains around Khorramabad. Their essential oils were extracted by Clevenger and their chemical composition analyzed by GC/MS. The antimicrobial activities were determined by disk diffusion and micro-dilution methods against Shigella dysenteriae, Escherichia coli, Staphylococcus aureus and Bacillus cereus. Thirty- nine and fifty-eight components were identified inEchinophora and Stachys essential oils, respectively. α-phellandrene, p-cymene, carvacrol and α-pinene were the main compounds in Echinophora essential oil and thymol, trans caryophyllene, β-phellandrene, spathulenol and caryophyllene oxide were the major components of Stachys essential oil. Findings showed antibacterial properties of Echinophora and Stachys. They acted against S. aureus with diameters of the inhibition zones of 34.5 and 22.8 mm, respectively. The minimum inhibitory concentrations (MIC) and MBC of Echinophorafor E.coli were 4.6, and 18.75 mg/mL. Results demonstrated that MIC of Stachys for all bacteria was 2.3 mg/mL. In addition, MBC of Stachys on E. coli and S. dysanteria was observed when it was adjusted on 2.3 mg/mL.
Volume 19, Issue 123 (May 2022)
Abstract
Recently, the tendency to use probiotic-potential starter cultures among lactic acid bacteria (LAB) isolated from non-dairy fermented substrates has been increased. The aim of this study was to isolate and molecularly identify the predominant LAB isolated from fermented germinated clover seeds, and also to evaluate its probiotic and antifungal properties. The LAB isolate was identified as Pediococcus pentosaceus, in accordance with the sequencing results of the PCR products. The antifungal and antibacterial effect of the isolate on Aspergillus niger and Staphylococcus aureus was significantly (P <0.05) higher than the other studied foodborne fungi and bacteria. Furthermore, P. pentosaceus isolate had a good survival (77.22%) in simulated gastrointestinal conditions. The isolate had no hemolytic activity, and its auto-aggregation activity was 35.51%. Also, the rate of co-aggregation of the isolate with Escherichia coli and S. enterica was equal to 48.71% and 18.43%, respectively. In addition, the bacterium was sensitive to the penicillin, cephalothin, ampicillin and cefazolin antibiotics.
Accordingly, it is possible to use the isolate as a probiotic culture with potential biological preservative in the food industry
Volume 19, Issue 132 ( February 2023)
Abstract
Evaluation of probiotic properties of lactic acid bacteria (LAB) isolated from fermented pseudocereals has crucial importance to prepare microbial cultures. In the present study, after molecular identification, probiotic properties of the predominant LAB isolate were investigated. Sequencing results of the PCR products led to the identification of Lactobacillus brevis SKA01 as the predominant LAB. The survival of the LAB isolate after continues treatment of acid and bile reached to 106 compared to the control sample (108 CFU/mL), and it showed the highest antibacterial effect on Staphylococcus aureus. Meanwhile, there was no significant difference (P>0.05) between inhibitory zone diameter of the S. aureus and Listeria monocytogenes in the present of the LAB isolate. LAB isolate was capable of good auto-aggregation (36.19%) and co-aggregation with S. aureus (71.24%), and it had no hemolytic activity. Furthermore, it was resistant to most of the tested antibiotics. By considering the proper probiotic potentials of the L. brevis isolated from fermented amaranth, it is possible to use the isolate as microbial starter or probiotic culture in fermentation industries.
Volume 20, Issue 9 (September 2020)
Abstract
P91 steel is widely used in the construction of power plant components and the wider use of this steel is in the future planning of power plants in Iran. The preheating, the temperature control between the welding passes and the post-welding heat treatment, are required to obtain optimum toughness and creep resistance. Preheating, and most importantly post-heating are essential to prevent hydrogen remaining and the cracking problem. In this study, the effect of post-welding heat treatment (PWHT) and electrode drying on microstructure and mechanical properties of SMAW multi-pass weldment of P91 steel plate was studied by changing post-heating and baking processes. The optical microscope and FESEM microstructural studies, as well as ambient tensile tests, were done on a variety of different conditions from wet electrodes to post heated specimens that were used in order to evaluate the welding characteristics of SMAW process on the mentioned material. It was seen that utilizing wet electrodes with no immediate subsequent post-heating caused a noticeable decrease in tensile, and yield strength. On the other hand, post-heating treatment increases the number of precipitates in the weld metal and HAZ and the size of the primary austenite grains in the weld metal and HAZ becomes more homogeneous.
Volume 22, Issue 158 (April 2025)
Abstract
Evaluation of probiotic properties of microorganisms isolated from stressful substrates has received considerable attention. Among probiotic microorganisms, yeasts are distinguished from lactic acid bacteria due to their bigger size, better adhesion ability, and resistance to antibiotics without the possibility of transferring resistance genes. In the present study, probiotic and antifungal properties of the predominant yeast isolated from natural honey were investigated. Sequencing results of the PCR products led to the identification of Saccharomyces cerevisiae as the predominant yeast isolated from honey. Moreover, the isolate had no hemolytic activity and showed the highest sensitivity towards natamycin among the studied antimycotic agents. In addition, although the yeast isolate had no proper survival under simulated gastrointestinal conditions, it had relatively high auto-aggregation (93.86%) and cell-surface hydrophobicity (76.36%). The highest co-aggregation ability of the isolate was also observed with Gram-positive bacteria Bacillus cereus and Staphylococcus aureus, and the inhibition activity of the isolate against B. cereus was significantly (p<0.05) higher than those of the other studied food-borne bacteria. The yeast isolate also showed 32.18% antifungal effect on Aspergillus flavus. Accordingly, the predominant yeast isolated from honey has suitable capabilities for application as a protective culture in fermentation industries.
