Sharif Digital Repository

In recent years there has been potential increase in the use of alkaline protease as industrial catalysts. Many major industrial and commercial applications, such as food and textile industries, and medical diagnoses, are highly dependent on the protease enzyme. In the cell immobilization technique, the free movement of microorganisms is restricted in the process, and a continuous system of fermentation can be used. In the present work, this technique has been used for alkaline protease production using different carriers, such as chitosan, corn cob and corn tassel. Enzyme activity before immobilization (72 h) was 78.3 U/ml. Corn cob, with 65% immobilization capacity and the highest enzyme... 

To describe immobilized cells in porous microcapsule membranes with straight pores, a novel model called corrugated parallel bundle model (CPBM) was utilized. In this model, a network was developed with 10 main pores each composing 10 pore elements. Cell growth kinetic in the network was examined using non-structural models. Effectiveness factor and pore plugging time were calculated by solving reaction-diffusion equation set via finite difference method. The findings revealed that diffusion coefficient for lower order reactions will create a lesser impact on the reduction of effectiveness factor. These findings also indicated that the use of such supporting carrier for cell immobilization... 

Lactobacillus acidophilus is one of the major microorganisms which are famous for their effects on cholesterol. In this study, we have investigated the effect of L. acidophilus ATCC 1643 on removing the milk cholesterol and additionally, we have immobilized L. acidophilus ATCC1643 cells in sodium-alginate and observed its effect on milk cholesterol removing. Also, we have researched about the effect of some factors including: bacteria cells number (both free and immobilized cells) and immobilized cells bead size on cholesterol removing rate and ultimately the extracted results were compared together. The results indicated that free cells could reduce cholesterol to lower than 0.5mg/100ml... 

E.coli was immobilized by entrapment within calcium alginate beads using cell suspensions of different concentrations. The immobilization procedure resulted in beads with a homogeneous cell distribution, referred to as a Non-overlapping Cell (NC) configuration. If cells within the beads were allowed to grow, the NC configuration would transform into a Clustered Cell (CC) configuration as a, result of cell growth. Enzyme activity and substrate conversion were obtained for NC and CC configurations of different cell density, using penicillin G acylation by penicillin G acylase, to produce. 6-amino penicillanic acid. Enzyme activity and conversion were found to depend on both cell concentration... 

A novel hydrogen sulfide microbial biosensor was developed based on investigating the influence of four design parameters: cell concentration, immobilization bed type, hydrogen sulfide concentration, and geometrical shape of the biosensor. Thiobacillus thioparus was used as the recognition element and it was immobilized on sodium alginate as well as agarose bed. The results were optimized by the application of statistical optimization software based on response time of the system. Oxygen reduction was considered as the detection sign. Sodium alginate solution with a concentration of 2.3% (w/v) and optical density of 10 at 605. nm was found as the optimum conditions for immobilization with... 

Rhamnolipids are the most common biosurfactants and P. aeruginosa strains are the most frequently studied microorganisms for the production of rhamnolipids. Eco-friendly advantages and promising applications of rhamnolipids in various industries are the major reasons for pursuing the economic production of these biosurfactants. This study shows that cultivation of P. aeruginosa MR01 in medium contained inexpensive soybean oil refinery wastes which exhibited similar levels and homologues of rhamnolipids. Mass spectrometry indicated that the Rha-C10-C10 and Rha-Rha-C10-C10 constitute the main rhamnolipids in different cultures of MR01 including one of oil carbon source analogues. Moreover,...