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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Iranian Journal of Biotechnology
- نوع مقاله: Journal Article
- کلمات کلیدی: Isolation,Characterization,Magnetotactic bacteria
- چکیده:
- چکیده انگلیسی: Several species of Magnetotactic bacteria have been discovered recently. These bacteria synthesize intracellular magnetic nanoparticles in specific sizes and shapes and arrange them in chains. These particles called magnetosomes and can be used for drug-delivery, cell-targeting and hyperthermia. Magnetotactic bacteria navigate along the magnetic field; this process is known as ‘magnetotaxis’ which may be very useful in robotic technology. In this research, two species of magnetotactic bacteria were isolated; freshwater specimens were collected from Karkheh River and marine specimens were collected from the Caspian Sea. After enrichment, two species of the Magnetotactic bacteria were isolated using a specific solid media culturing. The response of the two isolates to the magnetic field was observed by an optical microscope. SEM photos showed that the freshwater and marine bacteria are rod shaped. TEM images showed chains of magnetosomes in the bacterial cells. Also magnetic behavior of the magnetosomes was investigated by alternating-gradient-force magnetometer, indicating that the magnetosomes have superparamagnetic-to-single-domain properties.
- انتشار مقاله: 31-01-1394
- نویسندگان: Farhad Farzan,Seyed AbbasShojaosadati Shojaosadati,Hossein Abdul Tehrani
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Biotechnology
- نوع مقاله: Journal Article
- کلمات کلیدی: Recombinant protein,Expression system,High cell density culture
- چکیده:
- چکیده انگلیسی: This paper reviews recent strategies used for increasing specific yield and productivity in high cell density cultures. High cell density cultures offer an efficient means for the economical production of recombinant proteins. However, there are still some challenges associated with high cell density cultivation (HCDC) techniques. A variety of strategies in several aspects including host design consideration, tuning recombinant protein expression, medium composition, growth methodologies, and even control and analysis of the process have been successfully employed by biotechnologists to increase yield in high cell density cultures. Although most researches have focused on Escherichia coli, other microorganisms have the potential to be grown at high density and need further investigation. In recent years, information on physiological changes of hosts during different phases of cultivation derived from functional genomics, transcriptomics and proteomics is being used to overcome the obstacles encountered in high cell density cultivation and hence increase productivity.
- انتشار مقاله: 05-02-1394
- نویسندگان: Seyed Abbas Shojaosadati,Seyedeh Marjan Varedi Kolaei,Valiollah Babaeipour,Amir Mohammad Farnoud
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Biotechnology
- نوع مقاله: Journal Article
- کلمات کلیدی: Aspergillus niger,Control Strategies,Cooling Jacket,Packed Bed Bioreactor,Solid State Fermentation (SSF)
- چکیده:
- چکیده انگلیسی: Different control strategies of bed temperature and moisture were investigated using various inlet air temperatures and air fluxes in both the ordinary packed bed bioreactor (without cooling water in the jacket) and the bioreactor with cooling water in jacket. The experiments were carried out within a 1-L solid-state packed bed bioreactor in which Aspergillus niger was cultivated on wheat bran. On-line measurements of oxygen quantity in the outlet air and temperature of the bed and the inlet air flux were carried out in both types of the bioreactors. Effects of certain control strategies on fungal growth rate were compared in both the bioreactors. According to experimental results, using the bioreactor with the cooling water in the jacket is a better strategy for control of bed temperature and moisture during packed bed solid state fermentation. Cumulative oxygen consumption in this bioreactor was approximately 1.7 times higher than other control strategies used in this study.
- انتشار مقاله: 16-02-1394
- نویسندگان: Seyed Abbas Shojaosadati,Zohreh Hamidi-Esfahani,Parisa Hejazi,Ebrahim Vasheghani-Farahani,Arian Rinzema
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Biotechnology
- نوع مقاله: Journal Article
- کلمات کلیدی: Methanol,Pichia pastoris,Fed-batch culture,rhG-CSF
- چکیده:
- چکیده انگلیسی: Human granulocyte-colony stimulating factor (hG-CSF) cDNA was expressed in the methylotrophic yeast Pichia pastoris under the control of the alcohol oxidase (AOX1) promoter. An expression vector for hG-CSF secretion was constructed using vector pPIC9. Higher levels of hG-CSF was obtained using a P. pastoris Mut+ (methanol utilization fast) phenotype. The effects of environmental factors such as temperature and pH on the P. pastoris cell growth and hG-CSF production during fermentation were investigated. Cell growth and hG-CSF production were found to be optimal at 28°C and pH 6.0. A fed-batch fermentation process was also developed to obtain high cell density and higher levels of protein expression. Using a high cell density cultivation method, cell dry weight and hG-CSF concentration reached 100 g/l and 35 mg/l, respectively.
- انتشار مقاله: 19-02-1394
- نویسندگان: Ali Bahrami,Seyed Abbas Shojaosadati,Rasoul Khalilzadeh,Ali Reza Saeedinia,Ebrahim Vasheghani Farahani,Jafar Mohammadian-Mosaabadi
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Biotechnology
- نوع مقاله: Journal Article
- کلمات کلیدی: modeling,Cheese whey,External airlift bioreactor,Single cell protein,Tanks-in-series model
- چکیده:
- چکیده انگلیسی: In this work, mathematical modeling of microbial (Trichosporon sp.) biomass production in a stirred tank bioreactor and in an external airlift bioreactor has been investigated. A model based on a tanks-in-series model without back-flow has been used to simulate the production of single cell protein in the external airlift bioreactor under an unsteady condition and without oxygen limitation, utilizing cheese whey as a substrate. The kinetic parameters of cell growth and substrate consumption including µm(maximum specific growth), K s(growth associated parameter), γ(saturated constant) and λ(non growth associated parameter) were determined based on experimental data derived from the batch process in the stirred tank reactor and the kinetic model, which resulted in 0.59 h-1, 46.84 g/l, 0.383 and 1.275, respectively. Estimated biokinetic parameters were applied to find the profiles of biomass and lactose in the airlift bioreactor. MATLAB software was used to find kinetic parameters and solve the equations of the tanks-in-series model. The number of stages of the tanks-in-series obtained equals 16.
- انتشار مقاله: 19-02-1394
- نویسندگان: Marjan Varedi Kolaei,Ramin Karimzadeh,Seyed Abbas Shojaosadati,Jafar Towfighi
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Biotechnology
- نوع مقاله: Journal Article
- کلمات کلیدی: Physiological status,Recombinant Escherichia coli,Human Ineterferon-gamma,High cell density cultivation,Over-expression
- چکیده:
- چکیده انگلیسی: The objective of this research was to investigate the influence of the over-expression of recombinant interferon-g during high cell density cultivation on cellular characteristics of recombinant E. coli. Batch and fed-batch culture techniques were employed to grow Escherichia coli BL21 for production of human gamma-interferon in pET expression system. Final cell densities in batch and fed-batch cultivations were approximately 7 and 127 g cell dry weight (CDW) l-1, respectively. In both systems, specific growth rate decreased and reached zero, 4 hours after the induction. It was found that high cell density and over-expression of interferon-g had no substantial effects on cell lysis and plasmid stability. Plasmid content of the cells was nearly similar and remained constant during the post-induction period in both batch and fed-batch cultures (60 mg plasmid per g-1 CDW). In both systems, time profiles of acetate and lactate production were similar, lactate concentration was lower than that of acetate and the concentrations of both were lower than the inhibitory level. Maximum extracellular cAMP concentration occurred at the start of induction in fed-batch culture and was higher than the amount produced during the batch process. The size of E. coli cells reduced significantly as cell density increased and the morphology of the cells in high cell density changed from the usual rod shape to spherical, while the expression of interferon-g remained almost constant.
- انتشار مقاله: 09-06-1394
- نویسندگان: Seyedeh Marjan Varedi Koolaee,Seyed Abbas Shojaosadati,Valliollah Babaeipour,Nasser Ghaemi
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Biotechnology
- نوع مقاله: Journal Article
- کلمات کلیدی: Taguchi Method,Amino acids,Single cell protein (SCP),Natural Gas, Methylomonas,RNA Measurement
- چکیده:
- چکیده انگلیسی: Production of single cell protein (SCP) from natural gas in a one liter bubble column reactor and optimization of the process parameters were investigated. The medium specifications, nitrogen sources, initial inoculum volume, and inlet ratio of gas to air were considered as process parameters to be optimized. The optimum condition for highest biomass production in which the maximum quantity of protein was obtained, were the use of a certain carbon-less salt broth utilizable with methane (named as Methane Salt Broth/MSB) and sodium nitrate as medium and nitrogen source respectively. Also, 7%(v/v) inoculation size, and an inlet gas mixture
of 60/40 natural gas/air were determined as the effective inoculation and appropriate volume configuration of inlet gases. Protein production in optimum condition was 69.3%(w/w) of biomass in dry basis which its structural amino acids can be in comparable with other nutrient sources. An average amount of 10 g RNA out of 100 g of cellular protein [or 6%(w/w) RNA in whole biomass] was extracted from the biomass which is extremely near to the possible minimum of RNA distribution among bacteria. Heat shock treatment was applied for reducing the RNA in the biomass bulk. Heat Treatment at 60 to 65°C for 10 to 20 min provided
the best RNA reduction results (around 1 gram in 100 grams of protein). Regarding the structural amino acids and RNA content, the properties of single cell protein resulted in this experimental work, were in a frame which it could be consumed safely.- انتشار مقاله: 09-07-1384
- نویسندگان: Fatemeh Yazdian,Solmaz Hajizadeh,Seyed Abbas Shojaosadati,Rasoul Khalilzadeh,Mohsen Jahanshahi,Mohsen Nosrati
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Biotechnology
- نوع مقاله: Journal Article
- کلمات کلیدی: Human growth hormone,recombinant E. coli,Heat induction,High cell density culture
- چکیده:
- چکیده انگلیسی: The high cell density cultivation (HCDC) of a recombinant E. coli producing human growth hormone (hGH)
under different heat induction strategies has been reported. In this paper the effect of heat shock temperature, its duration and post-induction temperature, at two levels on cell growth and death, hGH production and its degradation, substrate utilization and by-product formation were investigated by full factorial experimental design. The results showed that heat shock temperature was the most effective factor on hGH production having approximately 75.8% of total contribution. There was no significant accumulation of substrate or by-product in culture medium during HCDC in all experiments. Thirty two percent of cells were subjected to lysis during the heat induction at 42°C for 20 min followed by 37°C for 4h. Biologically active recombinant hGH was produced comprising 13% of total cell protein without degradation. An empirical equation
was employed to describe the relationship between three factors and hGH production during HCDC.
- انتشار مقاله: 12-10-1383
- نویسندگان: Fatemeh Tabandeh,Seyed Abbas Shojaosadati,Bagher Yakhchali,Mahvash Khodabandeh,Mohammad Hossein Sanati
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Biotechnology
- نوع مقاله: Journal Article
- کلمات کلیدی: Volatile fatty acids,Biogas,Thermophilic anaerobic digestion,Waste food
- چکیده:
- چکیده انگلیسی: Different initial concentrations of slurry waste food (discarded food), with and without the overlying layer
of fat derived from the waste were anaerobically digested at 55°C. At solids concentrations less than 20
g/l no significant difference was observed in terms of volatile fatty acids and methane production between
samples containing fat layer and samples without it. However, at higher concentrations, differences
became more obvious. Biogas released from a 50 g/l fat excluded sample was around 100% more than the
gas generated from the fat included sample with the same initial solids concentration. Inhibition by propionate
was not significant in concentrations less than 2000 mg/l. In the absence of fats, the inhibition caused
by accumulation of propionate could be overcome partially by the methanogenic bacteria. Based on the
energy generated in the form of methane, it was found that thermophilic anaerobic digestion of waste food
could be an autothermal process for fat excluded feeds.
- انتشار مقاله: 10-07-1383
- نویسندگان: Mohsen Nosrati,Seyed Abbas Shojaosadati,Trichur Ramaswamy Sreekrishnan,Satya Narayan Mukhopadhyay
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Biotechnology
- نوع مقاله: Journal Article
- کلمات کلیدی: Glucose,Glycerol,Human interferon-gamma,Fed-batch cultivation,recombinant E. coli,Specific growth rate
- چکیده:
- چکیده انگلیسی: A simple fed-batch process with pre-determined exponential feeding strategy for high-cell-density cultivation
of recombinant E. coli BL21 (DE3) in defined medium was developed. In this feeding method glucose and
glycerol were used as the sole sources of carbon and energy to increase the cell density exponentially at
controlled specific growth rates, which do not cause the accumulation of acetate. Thus, sophisticated feedback
control or extra equipment to prevent the accumulation of toxic level of acetate is not necessary. The
final cell densities of 100 and 118 gl-1 of dry cell mass for recombinant E. coli producing human interferon-γ
(hIFN-γ) were obtained by using glucose and glycerol, respectively. The concentration of acetate was always
maintained below toxic level. The specific yield of hIFN-γ with glucose and glycerol was 93 and 92 mgg-1
of dry cell mass, and the overall productivity of hIFN-γ was 0.16 and 0.14 gl-1h-1 for these two carbon sources, respectively.
- انتشار مقاله: 13-01-1383
- نویسندگان: Rasoul Khalilzadeh,Seyed Abbas Shojaosadati,Ali Bahrami,Nader Maghsoudi
- مشاهده