Sharif Digital Repository

Biosurfactants are surface active compounds capable of reducing surface tension and interfacial surface tension. Biosurfactants are produced by a variety of microorganisms. They are promising replacements for chemical surfactants because of biodegradability, non-toxicity and being able to produce from renewable sources. However a major problem of producing biosurfactant in industrial level is their production cost. In this research, by using corn steep liquor as low-cost nitrogen source besides other nitrogen sources, not only production cost reduced but also a higher efficiency achieved. Therefore optimization of biosurfactant production was done by RSM and Box- Behnken method. Results... 

Trash production in Iran is increasing. The majority of trash is being buried and that induces the emission of methane gas (CH4), which is a greenhouse gas. In this thesis, the aim was mostly to remove methane from greenhouse gases by applying several cheap and abundant substances. For this purpose, a biofilteration system was provided. It has been tested using two packings: straw and plastic. To provide the necessary materials for bacterium growth, a nutrient solution was used. The results of this work have revealed that plastic proved to be more effective than another substance and the removal percent obtained was about 61%. The result for straw was 42%. Furthermore, the experiments were... 

In this study, Pseudomonas aeruginosa BBRC-10036 was used for lipase production. The organism secreted the enzyme extracellulary. First of all, effect of initial pH of the culture broth on lipase activity was studied in order to determine the optimum condition for lipase production. After production, this enzyme must be separated from culture and after that the enzyme must be purified for using in analysis and industry. Different methods are used for purification of the enzyme. In this research, first precipitation was used and then this lipase has been purified by Ion exchange Chromatography leading to 2.33- fold purification and 11.47% recovery. In precipitation by acetone, maximum... 

This thesis discusses the work on the production of a rhamnolipid-type biosurfactant by Pseudomonas aeruginosa MR01, its structural characterization and environmental applications. First, results from analytical approaches for screening of biosurfactant producers suggested the oil spreading method as the fastest, simplest and most consistent analytical method. The second part of the thesis describes the properties of the most efficient biosurfactant-producing bacteria isolated from oil fields in south of Iran and according to it’s biochemical characteristics and partial sequenced 16S rRNA gene affiliated with Pseudomonas aeruginosa. Time course study indicated that the maximum biosurfactant... 

In this study, biosorption of selenium by Pseudomonas putida bacteria was investigated in both single and binary uptake systems. Bacteria cells were immobilized in the chitosan beads, to study impact of microorganism entrapment on the sorption capacity of the fabricated adsorbent. Uptake capacity increased by the entrapped bacterial weight percent up to 20 wt. %; but thereafter, sorption capacity gradually leveled off with an increase in the loading percentage of the bacterial cells.The effects of the three process variables including pH (2-6), biomass dosage (0.5-2.5 g/L) and initial concentration of selenium (50-250 mg/L) on the uptake performance of adsorbent were investigated, and... 

Lipases (triacylglycerol acylhydrolases) are industrial enzymes that have wide applications in the detergent, pharmaceutical and food industries. Pseudomonas aeruginosa strain is known to be suitable for lipase production due to its stability in organic solvents, resistance to temperature and pH. Lipases are usually secreted extracellularly, and its isolation from the culture medium is very important. The most cost-effective separation method is filtration which is more economical than centrifuge. Here, the use of filtration method is important from two aspects of creating clearance and maintaining enzyme activity. The equipment in this research is the filter press, whose initial tests are... 

Lipases (Triacyl Glycerol Acyl Hydrolase, EC.3.1.1.3) are multidimensional biocatalysts which have many applications in food industrials, dairy, fats and oils processing, detergents, synthesis of pure chemical and pharmaceutical materials, paper industrial and cosmetics. Generally, industrial enzymes are produced extracellularly, so their separation from a low-cost complex medium (usually used for production) is one of the cost stages in their production process. Filtration is the most economical method of separation in the production of enzymes, but due to the small size of colloidal particles and cell masses present in the fermentation environment, its use is subject to limitations. In... 

The use of microorganisms to remove or produce a substace is a fundamental part of biotechnology. An example is the bioreactors for phenol removal in wastewater. Biological processes are commonly done in batch reactors in which suspended cells grow in the liquid phase. The batch process needs alternate reactor washes and alternate cell cultivation, which leades to a longer time constant for for each batch. If these reactors operate in continuous conditions, the cells will leave the reactor in liquid flow, and high cell concentrations will be impossible. The biofilm layer makes a batch phase, so the liquid phase flows in and out continuously, but the cells in the biofilm layer stay in the...