Modares Journal of Biotechnology

Abstract One of the most important hosts used for production of recombinant proteins is Escherichia Coli. For example, the most therapeutic proteins approved by FDA are produced in Escherichia Coli. Comprehensive knowledge about biologic nature of Escherichia Coli had made this microorganism to a favorable factory for production of recombinant proteins. Accessibility of this information have led to rational manipulation for changing of this small factory to intelligent system can make different recombinant proteins easier. So that, many engineered and useful strains were obtained from wild type and parental strains can produce high amount of diverse and stable recombinant proteins in lab and industrial scale. In this review, we will present some of these strains that are more widely used.

Abstract Abstract
Urinary tract infection is one of the most common and common bacterial infections, accounting for a significant proportion of hospital admissions (about 30-40%). Silver nanoparticles work by releasing silver ions against various bacteria. The fact that bacteria are not resistant to nanoparticles is very important and therefore will affect a wide range of bacteria.
Materials and Methods
In this study, 50 specimens of positive cultures with urinary tract infection referred to Imam Reza Hospital Laboratory in Bojnourd were studied. Resistance and susceptibility of the isolates were determined by disk diffusion method. In this study, antibacterial effects of silver nanoparticles were investigated by microdilution method using aqueous extract of Ganoderma leucidum. Vegetative electron microscopy was used to measure the size and shape of silver nanoparticles. In addition, infrared spectroscopy analysis was performed to investigate possible organic compounds involved in the synthesis of nanoparticles.
Results: The highest antibiotic resistance was related to ampicillin (84%). The resulting nanoparticles were 20 to 45 nm in size.
Conclusion:
The produced nanoparticles have antimicrobial activity and can be a good alternative in the treatment of antibiotic resistant infectious diseases.

Abstract Newcastle disease virus (NDV) is an infectious agent of a large variety of birds, including chickens, which poses a real threat to the poultry industry. This virus is a member of the avian Paramyxoviridae. NDV is enveloped with membrane-embedded spikes consisting of glycosylated hemagglutinin (HN) and fusion (F) proteins. The mean death time after vNDV infection is 2-6 days, hence, the presence of preexisting antibodies prior to infection appears to be the most critical protection from this disease. Antibodies produced against the HN and F trans-membrane surface glycoproteins are able to neutralize NDV upon subsequent infection and inhibition of viral fusion with the host cell membrane, respectively. In this experimental study, the immunogenic epitopes of the F protein of NDV were designed artificially and were expressed in the heterologous system (Escherichia coli), using the appropriate vector (pET32a). In order to evaluate the immunogenicity of the recombinant f fragment, the protein was injected into the animal model. Immune response and the rise of specific antibodies titers were determined in immune sera. The results showed that immunization of mice with this recombinant protein could elicit significant serum IgG antibody up to 1/204800 titer. We show that the recombinant F protein was recognized by the mice sera immunized with the commercial vaccine. Moreover, the reactivity of vaccine strain virus with sera from F protein immunized mice suggested that the F protein is able to present similar epitopes with viral vaccine strain and hopefully could stimulate the immune system of the animal against the infectious viruses.

Abstract Introduction: Growth hormone is a non-glycosylated polypeptide strand of the pituitary glands of all vertebrates that has a wide range of biological activities and considering the importance of this hormone and its importance and diverse therapeutic applications in medicine, its recombinant production can be of great importance. In recent decades, protein engineering and genetic engineering have resulted in a high level of expression and production of this protein in a variety of hosts, including Escherichia coli bacteria using new techniques and methodes, hormone purification and assay are carried out easily. Therefore, the aim of this review was to investigate the production of recombinant human growth hormone (rhGH) and future challenges.
Conclusion: One of the problems of the expression and purification of the human growth hormone may involve that maybe noted the production of inclusion bodies in the expression of recombinant proteins in the cell cytoplasm, the contamination caused by host proteins, low protein recovery from these inclusion bodies, low protein secretion into the Periplasmic space, high cost of production, especially in Purification stage and so on. Due to the lack of need for glycosylated hormone and high efficiency and simplicity of work, bacterial systems, especially Escherichia coli, are the most economical and effective systems for the expression of heterologous proteins. The hormone purification stage is usually the most costly process. Therefore, an optimal design for achieving the highest target protein recovery with the elimination of all contamination from the final product and reducing the purification step is required.

Abstract Sugar beet molasses is a well-known, inexpensive and available carbon source for microbial cell growth. Its sugar components are used to produce energy for microbial growth and non-sugar components, especially nitrogen components, have important roles in improvement of cell growth. On the other hand, immobilization of whole cell is establishment and physical limitation of intact cells in specific space that keeps their catalytic activity and provides the possibility of reuse of the cells. This technique allows continuous and accelerated biological processes. It also improves production efficiency and quality and simplifies recycling of product. Immobilized living cells, as controlled catalysts, are able to perform one-step enzymatic reaction and continuous fermentative processes. In this research, E.coli cells were immobilized in calcium alginate hydrogels and using sugar beet molasses as carbon source, were applied for tryptophan production reaction in the presence of its precursors, serine and indole. In comparison between free biocatalysts and immobilized bacterial cells that entrapped in alginate gels, indicated that larger amounts of amino acids (about 42/9%) can produce in calcium alginate. Also the production reaction was followed up for 9 sequential cycles, and results showed that the cells could produce tryptophan amino acid under above conditions. Use of sugar beet molasses (by-product of agriculture industries) for growth of microbial cells and tryptophan production, causes decrease in production cost and more economical production of tryptophan by immobilized E. coli.