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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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Charcoal rot caused by Macrophomina phaseolina is one of the most important soil borne diseases with a broad host range including bean, which annually brings a significant damage to this plant. Biological control of charcoal rot is very important because its chemical control harms the environment, microflora and soil fertility. Chemical control of charcoal rot is also difficult and sometimes ineffective. Fluorescent Pseudomonads are able to increase plant growth and inhibit the development of plant pathogens by producing and secreting antibiotics, enzymes, siderophores, and plant hormones. In this study, infected bean plants by M. phaseolina were collected from infected bean fields of Khorramabad (Lorestan Province, Iran) in the summer of 2015. Virulence of fungal isolates was evaluated in a greenhouse and one isolate with the highest pathogenicity was chosen for further experiments. The biocontrol potential of eight Pseudomonas fluorescens strains, whose biocontrol abilities were proved in previous studies, was examined against M. phaseolina in vitro. The growth inhibition of M. phaseolina was examined by dual culture test and the antifungal activity of bacterial volatile and nonvolatile metabolites. P. fluorescens UTPf125, which showed the highest inhibitory effect on the mycelial growth, was selected for greenhouse tests. UTPf125 strain led to a significant reduction (%50) of disease severity and increased fresh and dry weight significantly. Phenol compounds were evaluated 1, 3, 5, 7 and 9 days after inoculation by pathogen. The results showed that the highest value of total phenol content was obtained on the third and fifth days after inoculation, decreasing on the seventh and ninth days.