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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.
 

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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.
 



 

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One of the crises in the future for humanity is the epidemic of infectious diseases due to the antibiotic resistance of bacteria. Histatins family has antimicrobial activity against drug-resistant strains and wound healing properties. In this study, the first molecular dynamics simulation on Histatin 3 in the existence of water molecules and ions and also in the existence of Sodium Dodecyl Sulfate (SDS) micelle as a model of membrane bacteria was done separately via the GROMACS 5 package for 50 ns. Then, to increase antibacterial properties, eight mutations were designed and their structures were prepared. Then MD simulation was performed for each mutation with the same previous conditions and binding free energy via the MM/PBSA method of peptides with SDS micelle was calculated. Finally, 950 ns MD simulation in these conditions showed that the D1A-G9W mutation had the best binding free energy to the SDS micelle. Then this peptide and wild Histatin 3 peptide were synthesized, and antimicrobial properties were evaluated experimentally. The results of microbiological tests (MIC) indicated the value of this peptide, which is effective on gram-positive bacteria.