ABSTRACT
       Background and Objectives: Cellulose is a major component of plant biomass, which can be converted into biofuels and valuable chemicals. The key step in utilization of this organic material is its hydrolysis into soluble sugars. This study evaluated cellulase production by Trichoderma harzianum under different pH values, temperatures and incubation periods with the aim to increase enzyme production and decrease its costs.
Methods: The amount of protein production and the hydrolytic activity of cellulase enzymes including exoglucanase, endoglucanase and β-glucosidase produced by T. harzianum were evaluated using various substrates such as avicel, carboxymethyl cellulose, cellobiose, Whatman grade 1 filter paper under different pH values (4, 4.8, 5.5 and 6.5), temperatures (25, 28 and 34 °C) and incubation times (48, 72, 96 and 120 h).
Results: The optimum condition for cellulase production by T. harzianum is 120 hours of incubation at 25 °C and pH of 6.5.
Conclusion: T. harzianum can be used for the production of all three classes of cellulase. This fungus is suitable for the efficient production of cellulolytic enzymes and reducing the cost of consumables.
Keywords: Cellulose, Trichoderma harzianum, Hydrolytic enzymes, Optimization.

ABSTRACT
          Background and Objectives: Nonviral carriers including those based on synthetic cationic lipids, offer several advantages over the viral counterparts. These carriers are able to form complexes with nucleic acids and deliver genes into the cells via the cellular endocytosis pathway, without significant toxicity. The level of transgenes expression depends on some experimental variables including cell type and density, Lipofectamine and DNA concentrations and Lipofectamine-DNA complexing time. The main objective of this study was to optimize transfection of SW480 colon cancer cells with Lipofectamine 2000.
          Methods: In this study, SW480 cells were transfected with plasmid containing green fluorescent protein reporter gene using Lipofectamine 2000. Green fluorescent protein expression was studied under a reverse fluorescence microscope and the results were analyzed with the ImageJ software. Effect of different quantities of plasmid DNA and different Lipofectamine 2000 volumes on cell transfection efficiency was evaluated.
          Results: The optimal volume of Lipofectamine and quantity of plasmid was 2 µl and 1µg, respectively, which showed 59% efficiency for the transfection of SW480 cells at 24 hours post-transfection.
          Conclusion: This study shows that Lipofectamine 2000 is an efficient reagent for the delivery of genes into SW480 cells. According to the results, the quantity of DNA per transfection and reagent concentrations are essential factors for a successful transfection.
          Keywords: Optimization; pEGFP-NI; Lipofectamine; SW480.