Showing 3 results for Mutation
Khadijeh Bagheri, Samira Shahbazi, Hamed Askari, Shide Mojerlou, Farangis Amirlou,
Volume 4, Issue 4 (12-2017)
Abstract
Trichoderma species have been famous for production of cellulases with relatively high enzymatic activity. However, attempts to use their cellulolytic enzymes in the bioconversion of cellulosic wastes have not been successful because of high cost of production and low enzymatic yields. This study aimed to obtain gamma-induced mutants of T. viride with enhanced extracellular cellulase production. Spore suspensions were exposed to γ-rays at 250 Gy as optimum dose. After irradiation, all germinated spores were grown onto PDA plates and mutant strains with better sporulation were selected and subcultured five times to test their stability. Cellulase activity was tested using Whatman No. 1 filter paper, carboxymethyl cellulose, avicel, bacterial cellulose and walseth cellulose according to the IUPAC recommendation. Extracellular proteins profiles of mutant strains were studied via SDS-PAGE. The maximum activity of total cellulase and avicelase were observed in the isolate of M21 (92.43 and 74.40 U/mg, respectively) and maximum endo-glucanase activity was observed in M18 mutant. The results of this study showed that the application of gamma ray led to a significant increase in Cellulose activity of 38 percent of mutant strains. Thus, this method could be used as a simple and efficient way to achieve strains with the ability to produce high levels of enzymes and other biological metabolites.
Somayeh Farahmand, Faezeh Fatemi, Reza Hajihosseini,
Volume 6, Issue 1 (5-2019)
Abstract
In Acidithiobacillus ferrooxidans, the proteins present in the electron transfer pathway cause ferrous iron oxidation which leads to uranium extraction. The relationship between gene sequence and uranium extraction has not been investigated yet. Based on the changes in uranium extraction, the changes of rus gene sequence can reveal the direct and accurate role of this protein. For this purpose, a random mutation was induced in native Acidithiobacillus sp. FJ2 by two doses of 0.8% and 1% of DES. Then, the bacteria was transferred into a medium which contained 50% uranium ore to carry out the bioleaching process. After measuring the amount of the extracted uranium, iron, Eh and pH, genomic DNA was extracted to investigate the rusticyanin gene (rus) sequence sent for sequencing after performing PCR. Then, the wild-type gene sequence was compared with the mutant by Bioedit v7.2.5 software. The results showed that uranium extraction increased by mutant bacteria with DES 1% between 7-11 days in comparison with wild bacteria. However, there has been no change in the functional areas of the rusticyanin gene. It seems that DES affected other effective genes in the electron transport chain or regulatory areas, which required further studies.
Zahra Tavakoli, Behnaz Saffar, Karim Mahnam, Rohollah Hemmati,
Volume 11, Issue 3 (12-2024)
Abstract
A significant future challenge for humanity is the rise of infectious disease epidemics stemming from bacterial antibiotic resistance. The Histatin family exhibits antimicrobial properties against drug-resistant strains and promotes wound healing. This study aimed to engineer a novel mutant of Histatin 3 to enhance its antimicrobial efficacy. Initially, molecular dynamics simulations of Histatin 3 were conducted in the presence of water molecules and ions, as well as a Sodium Dodecyl Sulfate (SDS) micelle, which serves as a model for bacterial membranes, using the GROMACS 5 software for a duration of 50 ns. Subsequently, to augment antibacterial properties, eight mutations were designed, and their structures were prepared, followed by individual MD simulations under the same conditions for each mutation. The binding free energy of the peptides with the SDS micelle was calculated using the MM/PBSA method. Ultimately, 950 ns MD simulation revealed that the D1A-G9W mutation exhibited the most favorable binding free energy to the SDS micelle, indicating enhanced interaction of this mutant with microbial membranes. Both this peptide and the wild-type Histatin 3 were synthesized, and their antimicrobial properties were assessed experimentally. The microbiological tests (MIC) on gram-negative and gram-positive stains demonstrated that this peptide was effective against gram-positive bacteria. The findings of this research suggest that, in designing mutations to enhance antimicrobial properties, attention should be given to both the reduction of negative charge and hydrophobicity.
