A better way to measure critical attributes in bioreactors

Daniel Merriman, Strategic Marketing Manager, Thermo Fisher Scientific

It’s no secret that the pharma industry has been feeling the need for speed in the last few years. When the world asked for vaccines and therapeutics to be developed quicker than ever before, the industry responded and hundreds of potential vaccines and treatments were ushered into clinical trials within months.

But pharma companies couldn’t just move fast — they had to be careful and accurate because the world was waiting.

To help meet all of those needs, Thermo Fisher Scientific offers a line of mass spectrometers for gas analysis and fermentation in bioreactors, which is critical for monitoring the health of the culture and measuring small changes to oxygen and carbon dioxide concentration at key phases of the process.

Whether a company is using continuous or batch fermentation for bacterial, microbial or mammalian cell culture expression, Thermo Fisher’s gas analysis, mass spec product range, which includes its Prima BT and Prima PRO models provide precise off-gas analysis through every stage of fermentation, from the lab to the pilot plant to scale up. In addition, Thermo Fisher’s mass spec products work quickly and provide significant process control improvements that can be achieved usually within just a few days.

To learn more about the Prima BT and Prima PRO models, Pharma Manufacturing recently spoke to Daniel Merriman, the Strategic Marketing Manager at Thermo Fisher.

Q: Let’s start with some background on these technologies. Can you describe the relationship between gas analysis, mass spectrometry and process analytical technology as defined by the FDA?

A: The FDA itself supports the implementation of analytical technologies. When implementing PAT, users typically identify critical quality attributes that they wish to affect, usually attributes that might impact product yield or quality. The next step is to study critical process parameters that impact those quality attributes. And this is where online analysis comes in.

Gas analysis mass spec is one powerful tool for the study of these process parameters both directly by measurement of off-gas concentrations, such as oxygen or CO2, and then the utilization of that data to calculate parameters such as respiratory quotient. The goal is to use these process parameters to have better control of the process that ultimately yields better outcomes. And that’s really what PAT is about as far as the FDA is concerned.

Q: Could you tell me a little bit more about problems that pharma companies are trying to overcome when they’re using this type of analyzer?

A: Implementation of online process monitoring of a fermenter or bioreactor is not a trivial matter. If the intention is to perform online automated liquid phase sampling, these can be complex systems. Whether the analysis is done online or offline, measurements at the fermenter often require high-value analyzers, which are costly to use from a consumable perspective.

The intention of online gas analysis though, particularly by mass spectrometry, is to make these measurements low-risk so that they should be fully automated and able to provide process data that can reduce the dependence on offline testing, but also to produce that data in real time, without the need for manual intervention. So, it turns it into an automated, online method.

Q: Are there simpler or cheaper methods for this?

A: For gas analysis there are, but they’re not likely to facilitate the online measurements from a large number of fermenters. A mass spec could sample as many as 50 fermenters with a single system. And I should also note that the measurement precision of lower cost sensors is typically rather poor compared to mass spectrometry.

But another advantage of mass spec, which isn’t available to other techniques, is that mass spec can measure more than just simple oxygen and CO2 components. For example, ethanol and methanol are routinely measured in fermentation processes by mass spec. And that doesn’t add any cost to the solution.

Q: Speaking of costs, mass spec can be known to be a little bit more expensive, but is it a cost-effective solution in the long term?

A: Yes. A single mass spec could be utilized for many fermenters from a single analyzer. So, cost per point comes down very quickly. But as you said, it’s not all about the initial cost. Operating costs of mass spec are very low, but the value of the measurements are very high.

Q: Let’s talk about integrating mass spec if a company goes ahead and decides that they want to use this kind of system. You’ve described it as being relatively simple and low-risk. Can you elaborate on that a little bit more?

A: Measurements of sparge gas and vent gas from fermenters and bioreactors by mass spec require the mass spec to be entirely outside of the sterile environment. There’s no interruption to the process or interference to the fermenter or bioreactor. These systems also provide a very reliable measurement method.

So, that’s how they are a low-risk implementation.

Q: There are of course many different types of processes that are used in biopharma production. Can you tell me a little bit more about how this technology is suitable for those different types of processes?

A: Generally, it’s been applied to microbial and mammalian cell cultures for the development and production of many types of products.

So, it’s mainly used in the pharmaceutical industry, but it’s also applicable to agricultural products, bio-materials and biofuels. And for the latter, there is a lot of interest in it.

Q: In biopharma, there’s a lot of interest in mammalian cell culture. Tell me a little bit more about how this technology is used for this application.

A: There are already some excellent studies on the use of online mass spec for cell cultures. In general, the measurements are similar to microbial fermentation, but mass spec has a very impressive linear range for the gases that are required to be measured. And that’s especially useful in cell culture because the concentrations of the sparge gas and vent gases can vary significantly.

Also, mass spec is very precise and again, in cell culture, the changes in CO2 and oxygen in the respiratory gas concentration changes can be very, very small. And mass spec is precise enough to measure those small changes reliably, whereas other techniques would not be able to.

Q: What kinds of advantages can companies realize by implementing this solution?

A: If I could summarize the advantages that have been gained given the things we’ve discussed so far, I’d say it’s to have this real-time insight into cell metabolism that really enables the realization of PAT goals such as improving performance attributes. But it can also enable the prevention and minimization of poor process quality.

Q: But every process in biopharma production has its drawbacks and limitations as well. What are some of the limitations of mass spec?

A: One limitation, which is common to gas analyzers, is that they need a minimum sample gas flow. In some fermentation and cell culture processes, where the volume of the bioreactor is small, it’s currently impractical to use online gas analysis to monitor them. So, there certainly are some limitations in that respect.

Q: Of course, vendors for pharma companies are always looking at ways they can innovate their solutions to make life easier for pharma manufacturers. So, what’s next for gas analysis mass spec?

A: I think solving the above limitation would be a good start, but I think from where we are today, I do see an expected increase in the use of this technology for mammalian cell cultures, but also an extension of many other types of products, which are made by fermentation [and] are likely to use gas analysis mass spectrometry. Something, for example, like green energy such as biofuels and biomaterials.

So, I think that we will see a continued extension of different applications that have fermentation or cell culture.