h .askari

Cellulases and xylanases are hydrolytic enzymes that randomly cleave the β-1, 4 backbones of the cellulose and arabinoxylans of wheat flour and are widely used in the bakery industry as a dough texture improver in the formulations of flour products. Creating novel sources of a microbial strain using induced gamma irradiation can increase enzyme production for bakery industrial usage. According to this, Co60 gamma irradiation has been used to develop a mutant strain of Trichoderma afroharzianum. Trichoderma mutants were isolated, and the qualitative and quantitative screening were used to evaluate the extracellular enzyme production with the wheat bran waste as a substrate. The best Trichoderma mutant isolate was identified using the DNA barcoding method. The highest xylanase activities were observed in the superior mutant isolate of Trichoderma afroharzianum NAS107-M82, which is approximately 3.3 times higher than its parent strain. The electrophoretic pattern of proteins showed that the exo-glucanase I, endo-glucanase III, and the xylanase I enzymes hydrolyzed the wheat bran, synergistically. Overall, gamma irradiation-induced mutation could be an expedient technique to access such superior mutants for the bioconversion of wheat bran wastes to xylanase enzyme.

The present study investigates lithofacies and petrofacies in details and also reconstructs the depositional environment of the Paleocene siliciclastics of the Kerman Formation located in NE Central Iran, which is composed significantly of polymictic conglomerate bodies intercalated with some minor sandstone beds. Through detailed sedimentological studies (e.g., dominant grain size, degree of clast rounding and sorting, texture, and stratification), five lithofacies have been identified: clast-supported massive conglomerate (Gcm), matrix-supported massive conglomerate (Gmm), horizontally stratified conglomerate (Gh), horizontally bedded sandstone (Sh), and massive sandstone (Sm). Petrographic analysis revealed three petrofacies composed of petromict conglomerate, volcanic arenite, and feldspathic litharenite; gravels chiefly made up of basalt and andesite, as well as fewer limestone and agglomerated tuff. The lithofacies associations are related to sedimentary gravity flow (SG) and channel-fill sandstone bodies (CH) deposited in alluvial fan and braided fluvial systems. This research provides important insights into the sedimentary environments of the Kerman Formation.

Aflatoxin is one of the most important causes of contamination in dairy products, which has shown resistance to removal through various methods. This study aimed to molecularly identify yeasts isolated from local cheeses and screen them based on their ability to reduce aflatoxin B1. To carry out this study, 32 samples of local cheese were prepared from different geographical locations of Tehran and Semnan provinces in Shahryar, Firoozkooh, Chetan and Garmsar. Then the yeast strains were isolated from the samples. Aflatoxin stock solution was prepared and added to the culture medium containing aflatoxin absorbing yeast strains. Adsorbed aflatoxin was measured indirectly by ELISA test. The data of this study showed that 3 strains including Code 6, Code 18, and Code 8 isolated from local cheeses had the ability to detoxify aflatoxin B1. Meanwhile, the highest reduction of aflatoxin B1 in the environment with 46.5% was done by strain code 6. In addition, it was found that the optimum growth temperature of these strains was between 28 and 36 ˚C and their optimum pH was 6.5-5.5. Since the biological removal of aflatoxin has many positive effects on dairy products from various sensory and health aspects, it seems that the yeast strains isolated in the present study were microorganisms with the potential to remove aflatoxin from dairy products, especially local cheese, and should be considered for further studies.

The role of extracellular enzymes in mycoparasitism of Trichoderma spp. have been demonstrated in several cases. Trichoderma spp . produces several chitinolytic enzymes and this fungus is known as a powerful antagonist against Macrophomiona phaseolina, the causal agent of charcoal rot disease of soybean. In this study, two–dimensional protein pattern analysis and chitinaseactivity evaluation were performed for an Iranian Trichoderma koningii strain (NAS–K1) and its generated mutants were measured to indicate the potential role of endochitinases (N–acetylglucosam–inidase (NAG–I and NAG–II)) in its mycoparasitism. The results of chitinase activity assay using chitin and cell walls of M. phaseolina as substrates showed that the mutant isolates have significantly more enzyme activity compared to the wild type strain. The specific endochitinase enzyme activity in the mutant NAS–K1M25 was increased to approximately 2.5 times more and secreted three times more endochitinase than that of the wild type strain. This superior mutant showed up to 65% growth inhabitation against M. phaseolina in dual culture test (five times more than the wild type strain). Moreover, this strain showed sharper spots belong to endochitinase, and N–acetylglucosaminidase (I & II) presented in SDS–PAGE and 2D electrophoresis. Overall, induced mutation by gamma irradiation could be a useful method to develop such superior mutants, and the mutant NAS–K1M25 could be used as a potential biological control agent candidate for plant disease management programs of M. phaseolina. However, more detailed fermentation, formulation and field trial studies should be performed to finalize its biocontrol potentials.

One of priming methods to increase seed germination and seedling growth is gamma irradiation. In the present research, effects of various doses of gamma ray on germination and vegetative traits of cereals, legumes and vegetables were investigated. Irradiation was carried out using gamma cell with 60Co source of 7.8×102 Ci, with irradiation velocity of 0.087 g.s-1 in four levels (10, 20, 30 and 40 Gy) in a completely randomized design with 3 replications. The results showed that germination in wheat, corn, chickpea, and tomato seeds had positive reaction to low doses of gamma radiation; However, bean and onion seed germination decreased with increasing germination dose. In mungbean, cucumber, and lettuce seeds, germination percentage increased for higher doses. The response of different seeds to gamma radiation levels is different, and for some seeds such as wheat, corn, mungbean, chickpeas, tomatoes, and cucumbers, priming with gamma irradiation can be used to increase the percentage of germination and seedling growth. In other vegetative traits no increment was observed in beans, onions, and mungbean, compared to control but the seeds of chickpeas, wheat, corn, cucumber, lettuce, and tomato increased compared to control and showed a positive reaction to priming with gamma irradiation.

The HCCI combustion process is initiated due to auto-ignition of fuel/air mixture which is dominated by chemical kinetics and therefore fuel composition has a significant effect on engine operation and a detailed reaction mechanism is essential to analysis HCCI combustion. A single zone-model permits to have a detailed chemical kinetics modeling for practical fuels. In this study a single-zone thermodynamic model with detail chemical mechanism is developed to investigate the effect of hydrogen addition to natural gas in a homogeneous charge compression ignition combustion and to analyze the performance and emissions of the HCCI engine. The effect of five different percentage of hydrogen added to natural gas ranging from 0 to 40 on HCCI combustion is investigated in this study. The results indicate that by increasing hydrogen portion in intake mixture, start of combustion advances and maximum temperature increase, but increasing in maximum pressure is negligible. Carbon’s included emissions such as Co, Co2 and unburned hydrocarbons decreases by increasing of hydrogen, and also, specific fuel consumption decreases. The result shows that hydrogen improves combustion characteristics of natural gas in an HCCI engine and leads to better performance and less emissions.

One of the most important pest in the Oak forest of Kurdistan province is Oak leaf roller moth, Tortrix viridana L. (Lep.: Tortricidae). Use of pheromone trap is one of the suitable methods for monitoring and controlling of the pest. In this work, three main factors which affect the efficiency of traps including trap type, pheromone dose and installation height trap were studied. Four types of trap including cylindrical, rectangular, delta and wing trap were tested. Capture efficiency of the traps, were installed in the middle, and top heights of the trees were compared. Three doses of pheromone 0.5, 1, and 1.5 mgr per trap were also compared. Results showed that there were significant differences among four types of traps. Cylindrical, rectangular and delta traps caught more number of moths than wing trap (P<0.05). There were no significant differences between two installation heights (P>0.05). However, a significant differences was observed among three doses (P<0.05), and the dose of 0.5 mg caught more moths than the other three doses. Therefore cylindrical traps containing 0.5mg of synthetic sex pheromone installed in the middle of the trees canopy may be recommended in the management program of the pest.

Date fruit as a high calorie and valuable food source can be one of the main Iranian agricultural commodities for export, if properly processed and packed. The aim of this study was to process Kabkaab date variety from Routab (high moisture dates) to Tamar (known as dates or dry dates) using an industrial cabinet dryer. The Routab samples were dried using hot air at 56, 66, 76, 86 and 96 ˚C and changes in weight, moisture, pH, colour, texture and density of the dried samples were monitored. The results indicated that at 56 and 66 ˚C, drying rate was too low to be economic for an industrial process. At 86 and 96 ˚C the drying rate was high, although quality factors like colour was not acceptable. Therefore 76 ˚C is recommended as the best temperature for drying dates fruit. Moisture range of 24-27% (db) was the critical moisture level where a sharp decrease was observed in drying rate. Textural experiments of dates fruits with a wide range of moisture contents showed that above 30% moisture the hardness does not change with moisture level however, below 30% a small change in moisture can have a considerable impact on texture.