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12.
Viki R. Chopda Timothy Holzberg Xudong Ge Brandon Folio Michael Tolosa Yordan Kostov Leah Tolosa Govind Rao 《Biotechnology and bioengineering》2020,117(4):981-991
Dissolved carbon dioxide (dCO2) is a well-known critical parameter in bioprocesses due to its significant impact on cell metabolism and on product quality attributes. Processes run at small-scale faces many challenges due to limited options for modular sensors for online monitoring and control. Traditional sensors are bulky, costly, and invasive in nature and do not fit in small-scale systems. In this study, we present the implementation of a novel, rate-based technique for real-time monitoring of dCO2 in bioprocesses. A silicone sampling probe that allows the diffusion of CO2 through its wall was inserted inside a shake flask/bioreactor and then flushed with air to remove the CO2 that had diffused into the probe from the culture broth (sensor was calibrated using air as zero-point calibration). The gas inside the probe was then allowed to recirculate through gas-impermeable tubing to a CO2 monitor. We have shown that by measuring the initial diffusion rate of CO2 into the sampling probe we were able to determine the partial pressure of the dCO2 in the culture. This technique can be readily automated, and measurements can be made in minutes. Demonstration experiments conducted with baker's yeast and Yarrowia lipolytica yeast cells in both shake flasks and mini bioreactors showed that it can monitor dCO2 in real-time. Using the proposed sensor, we successfully implemented a dCO2-based control scheme, which resulted in significant improvement in process performance. 相似文献
13.
M. Lourdes Velez‐Suberbie Richard D. R. Tarrant Andrew S. Tait Daniel I. R. Spencer Daniel G. Bracewell 《Biotechnology progress》2013,29(1):116-126
Stirred tank bioreactors using suspension adapted mammalian cells are typically used for the production of complex therapeutic proteins. The hydrodynamic conditions experienced by cells within this environment have been shown to directly impact growth, productivity, and product quality and therefore an improved understanding of the cellular response is critical. Here we investigate the sub‐lethal effects of different aeration strategies on Chinese hamster ovary cells during monoclonal antibody production. Two gas delivery systems were employed to study the presence and absence of the air–liquid interface: bubbled direct gas sparging and a non‐bubbled diffusive silicone membrane system. Additionally, the effect of higher gas flow rate in the sparged bioreactor was examined. Both aeration systems were run using chemically defined media with and without the shear protectant Pluronic F‐68 (PF‐68). Cells were unable to grow with direct gas sparging without PF‐68; however, when a silicone membrane aeration system was implemented growth was comparable to the sparged bioreactor with PF‐68, indicating the necessity of shear protectants in the presence of bubbles. The cultures exposed to increased hydrodynamic stress were shown by flow cytometry to have decreased F‐actin intensity within the cytoskeleton and enter apoptosis earlier. This indicates that these conditions elicit a sub‐lethal physiological change in cells that would not be detected by the at‐line assays which are normally implemented during cell culture. These physiological changes only result in a difference in continuous centrifugation performance under high flow rate conditions. Product quality was more strongly affected by culture age than the hydrodynamic conditions tested. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2013. 相似文献
14.
Leuconostoc mesenteroides BLAC was grown on MRS broth or on a carrot juice medium, and the effects of sugar concentration, type of pH control, aeration
and fermentor size on viable counts were examined. The effect on viability of the type of centrifuge used to concentrate the
bacterial culture was also examined. When the MRS broth had the traditional 110 mM glucose, pH control did not increase the
final population. However, using a zone pH control mode, increasing the glucose content of MRS both from 110 to 220 mM almost
doubled the population. In MRS broth, the amount of acetic acid produced was the same for all treatments, and was proportional
to the amount of citrate consumed. There was a significantly lower cell yield in the carrot juice medium when the pH was not
regulated. In the carrot juice medium, pH had a more pronounced effect on the final population level than did aeration, even
though the quantity of viable cells was greater when the culture was aerated. In MRS broth, glucose was completely consumed
during fermentation, but this was not the case in carrot juice medium. Aeration resulted in increased acetic acid content
of the fermented medium. Viable counts were not affected by scaling the volume of the fermentation from 2 to 15 l ,or by the
type of centrifuge used to concentrate the cells. Cells were concentrated by a factor of 10, but in both centrifuge types,
viable counts showed only an eightfold average increase. However, freeze-dried powders obtained from the continuous pilot-plant-centrifuged
cultures had, on the average, 33% lower populations than those obtained from the laboratory unit. Journal of Industrial Microbiology & Biotechnology (2002) 28, 291–296 DOI: 10.1038/sj/jim/7000245
Received 09 July 2001/ Accepted in revised form 25 January 2002 相似文献
15.
Dinitrogen oxide production by a mixed culture of nitrifying bacteria during ammonia shock loading and aeration failure 总被引:2,自引:0,他引:2
Burgess JE Colliver BB Stuetz RM Stephenson T 《Journal of industrial microbiology & biotechnology》2002,29(6):309-313
A number of experiments was conducted in order to establish if N2O in the exhaust gas from an aerobic consortium of nitrifiers could be used as an indicator for monitoring the nitrification
process. Laboratory-scale experiments with an activated sludge system showed a strong correlation between ammonia shock loads
and both the concentration of N2O and the rate of increase of N2O in the exhaust gas for shock loads less than 1.60 mg ammonical nitrogen (NH3-N) per g total suspended solids (TSS). For greater ammonia shock loads, correlation was found between build-up of nitrite
in the aeration tank and the concentration of N2O in the exhaust gas from the tank. When subjecting the system to aeration failure, a similar pattern was seen, with a correlation
between nitrite build-up in the aeration tank and increases in the concentration of N2O in the exhaust gas. The results from this work suggest that the changes in N2O concentration in the exhaust gas from a nitrifying process may be a useful parameter for monitoring such processes.
Received 15 October 2001/ Accepted in revised form 05 June 2002 相似文献
16.
Aeration is a promising alternative to the use of pesticides for the control of storage insects by cooling bulk grain, but
its effectiveness against mite pests is neither fully understood nor optimised. For this reason, the productivity of three
species of storage mites, Acarus siro, Lepidoglyphus destructor and Tyrophagus longior, was studied in a laboratory-based experiment at four combinations of temperature and humidity (10°C and 70% RH, 10°C and
80% RH, 20°C and 70% RH, 20°C and 80% RH) with and without an airflow (at 10 m3/h/tonne, equalling 2.5 l/s/tonne, in tubes containing 15 g of grain). This is the first time that a study has examined the
three principal components of aeration separately from each other. The effect of these factors was different for each species.
For A. siro, temperature was the most important factor, while airflow and humidity were of similar but lesser importance. For T. longior, temperature was more important than humidity, while the reverse was true for L. destructor. For these two species, airflow was the least important factor. The airflow decreased the productivity of L. destructor and T. longior but increased the productivity of A. siro. This increase in productivity confirms that, in practice, prevention of mite infestations, in particular A. siro, will require storage of grain at low temperature, relative humidity and moisture content.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
Characterization of oxygen transfer in vertical microbubble columns for aerobic biotechnological processes 下载免费PDF全文
18.
对拟干酪乳杆菌发酵产乳酸的过程进行研究,通过改变不同的通气量(不通气、0.1vvm、0.2 vvm、0.5 vvm)确定0.1vvm的通气量最有利于产生乳酸;再通过优化通气策略,在发酵0~15 h不通空气,15~50 h通0.1 vvm空气使得乳酸的产量比全程通0.1 vvm空气又提高了11.7%,同时乳酸产率也提高了16.2%。最后通过对胞内NAD~+、NADH、乳酸脱氢酶和NADH氧化酶活性、以及发酵过程氧化还原电位(Oxidation-reduction potential,ORP)变化进行分析,阐述了通气影响乳酸发酵过程的机理。 相似文献
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