Scaled-up batch production was carried-out in a 7.5 l bench-top fermenter (BioFlo/Celligen 115, New Brunswick, USA) with a 3.0 l working volume. The fermenter was equipped with all the basic automation requirements (pH-mV controller - Mettler Toledo, USA; DO probe - Mettler Toledo, USA; temperature; aeration; and agitation). Other critical (physical) factors like agitation, temperature and aeration were maintained at 100 rpm, 37 °C and 1.0 vvm, respectively. The culture medium was the optimised basal medium having 10.25 % starch, 5.0 % peptone and 5.18 % yeast extract, and pH 7.3. A 1.21-fold increase in amylase activity observed in a scaled-up study,fermenter compared to the batch fermenter in laboratory shaker hints at the possibility of large-scale production of amylase for several industrial applications.
Do probe
Manufactured by Mettler Toledo
Sourced in United States
The DO probe is a measurement device used to determine the dissolved oxygen content in liquids. It functions by detecting the concentration of dissolved oxygen present in a sample, providing a quantitative measurement.
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Lab products found in correlation
5 protocols using do probe
1
Scaled-up Amylase Production in Bioreactor
2
Cultivation of iPSCs in Stirred Tank Bioreactors
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BioBLU 3c stirred tank bioreactors (Eppendorf) and 125 ml spinner flasks (Corning) were used in this study. The BioBlu 3c was equipped with dissolved oxygen (DO) probe (Mettler Toledo) and a pH probe (Mettler Toledo). The pH probe was calibrated using a two‐point calibration method with standard pH solutions. For the DO probe calibration, vessels were filled with RPMI‐1640 medium (1500 ml) and aerated with air and 5% CO2 by headspace gassing under the process conditions (i.e., 68 rpm agitation, 37°C) for at least 6 hr. After stable DO values were observed, a slope calibration was performed. The basal RPMI‐1640 medium was removed after DO calibration, and iPSCs were inoculated at 1.0 × 106 cells/ml in 1500 ml of L7 medium supplemented with 10 μM Y‐27632 (referred to as Day 3). The BioBLU 3c was agitated at 68 rpm from Day 3 to 0. Also from Day 2 to 0 the medium was exchanged every day in the bioreactor by removing 50% of the supernatant and adding in the same amount of fresh L7 medium into the bioreactor.
The spinner flask was inoculated at 1.0 × 106 cells/ml in 100 ml of L7 medium supplemented with 10 μM Y‐27632. The spinner flask was placed on a magnetic stir plate agitated at 70 rpm in a humidified incubator operating at 37°C and 5% CO2. From Day 2 to 0, 50% of the spinner flask supernatant was removed every day and replaced with 100 ml of fresh L7 medium.
The spinner flask was inoculated at 1.0 × 106 cells/ml in 100 ml of L7 medium supplemented with 10 μM Y‐27632. The spinner flask was placed on a magnetic stir plate agitated at 70 rpm in a humidified incubator operating at 37°C and 5% CO2. From Day 2 to 0, 50% of the spinner flask supernatant was removed every day and replaced with 100 ml of fresh L7 medium.
3
Optimizing Oxygen Supply for Batch Fermentation
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The oxygen supply was also analysed during batch fermentation in a 10 l bioreactor (Biotech-10JS, Shanghai, China) with 7 l working volume. The DO probe (Mettler-Toledo GmbH, Switzerland) and pH probe (Mettler-Toledo GmbH, Switzerland) measured the DO, pH and temperature, agitation speed were measured online. The pH was adjusted using 2.0 mol l−1 NaOH or 2.0 mol l−1 HCl. The temperature was controlled automatically. Different constant DO 20%, 30%, 40% and 50% in 10 l bioreactors were studied. The three-stage controls were performed as follows: during 0–24 h, the DO was set to 40%; during 24–96 h, the DO was set to 50%; and during 96–240 h, the DO was set to 30%. The four-stage oxygen controls were performed as follows: at Phase I (0–24 h), the DO was set to 40%; at the subsequent culture Phase II (24–96 h), the DO was set to 50%; at Phase III (96–192 h), the DO was set to 30%; at Phase IV (192–240 h), the DO was set to 25%. The DO level (percentage of air saturation) was controlled at constant values (20%, 30%, 40% and 50%) or varying values by cascading different agitation speeds (from 150 up to 500 r.p.m.), and the ventilation was 1 vvm throughout. The other culture conditions were the same as in the above experiments. Three batches were repeated for each experiment.
4
Monitoring pH and Dissolved Oxygen
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The level of pH and dissolved oxygen in the DH water were monitored using a bypass unit connected to the operating pipeline. The bypass unit consists of a flow chamber, a dissolved oxygen sensor (DO probe, Mettler Toledo, Columbus, OH, USA), and a pH meter (3-2716, GF Signet, Irwindale, CA, USA). The data were recorded every 30 min for 250 days.
5
Measuring Dissolved Oxygen Probe Response and Kla
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The measurement of probe response time for a polarographic dissolved oxygen (DO) probe and k L a in a benchtop bioreactor and a pilot-scale bioreactor were performed as previously described (Leth and McDonald, 2017) (link) with slight modifications. The step change from pure N 2 (medical grade) to pure O 2 (medical grade) was used to measure the response time of a DO probe (Mettler Toledo, Billerica, MA) in deionized (DI) water in two Erlenmeyer flasks saturated with pure N 2 in one flask and pure O 2 in the other flask. To evaluate k L a inside a bioreactor, the DO probe is inserted into the bioreactor containing DI water where temperature was maintained at 27@C. The DI water (4 L in the benchtop bioreactor and 30 L in the pilot-scale bioreactor) was sparged with pure N 2 until the %DO reached 0. Then the gas inlet was switched to industrial air, and the changes of %DO were recorded until a steady state %DO was reached (˜100% DO air saturation). Three replicate trials were performed for finding probe response time and k L a values. By using the dynamic method with significant oxygen probe response, the collected data points were fitted in the equations suggested by Blanch and Clark (1997) using the method of least squares in MATLAB ® (MathWorks Inc, Natick, MA).
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