Fermentation & Cell Culture FAQs

"I'm not getting any pH readings on my fermentor - how can I tell if it's a faulty probe, or my fermentor?"
We recommend an inexpensive hand-held pH/DO probe simulator that checks the functionality of your pH and DO electronics in the bioreactor and the probe cables. It easily pays for itself the first time you avoid an unneeded visit by a member of our repair/service team. Request catalog number P0720-5631.
"We are having problems with DO probe stability and response. Any suggestions?"
Broadley-James recommends the following technique:
  1. Disassemble tip.
  2. Dab toothpaste onto a moist Kimwipe.
  3. Clean the anode first (very important) followed by the cathode. The cathode must look like polished silver.
  4. Rinse with copious quantities of DI water.
  5. Rinse with electrolyte.
  6. Reassemble tip end.
  7. So much as a finger print on the anode will decrease probe response.
"Is supervisory software really necessary for use in our microbiology lab? We have just one fermentor, no programming experience, and prefer to spend our time doing science, not working on computers.?"
AFS-BioCommand™ software was designed to be used by biological scientists with little or no programming ability. Unlike more generic control software AFS-BioCommand was designed entirely by NBS for use exclusively with bioreactors and fermentors. This means you can expect minimal set up time, familiar jargon, and features that are appropriate for your application. The software won't waste your time.

As far as "do you need it?", if you are not already using supervisory software, it is unlikely that you really "need" all of the features of AFS-BioCommand. But, you will surely reap immediate benefit from the automatic data recording feature that eliminates curled-up strip-charts and "human break" data gaps. Also, you will probably find the variety and graphics of computer displays more friendly than the numbers that appear on most fermentor controllers. New AFS-BioCommand owners initially shy away from the "programmed fermentation" features until they get comfortable with the software. It is amazing how, in time, the luxury of unattended running over the weekend becomes a necessity.

"What kind of computer hardware is needed to use AFS-BioCommand?software with my fermentor / bioreactor?"
AFS-BioCommand requires a common variety, off-the-shelf "Windows™" computer. Technically, we specify it as having a Pentium (or higher) class processor with 16 MB (or more) of RAM, but this really translates to "garden variety" computer. One caution: AFS-BioCommand does not work with Macintosh™ computers.
"I see you offer left- and right-hand pitch marine blade impellers. Do I need both, and which way should they be installed?"
With marine blade impellers, both a left- and right-hand blade are needed. The right-hand blade provides up flow; the left provides down flow, assuming shaft rotation is clockwise. We recommend positioning the right-hand up-flow blade at the bottom of the shaft, and the left-hand down-flow blade at the top.

How to Identify a Right-Hand from a Left-Hand Propeller

Viewed from the tip when resting on a flat surface,
the blades of a left hand propeller points to the left.
Likewise, a right-hand propeller points to the right.
"How can I sample cells directly in a packed-bed basket bioreactor?"
The requirement for sampling cells originates from suspension applications, where operators determine the cell viability and density daily. The basket is operated differently, and optimized for product yield. We measure glucose, lactate, glutamine (if applicable) and ammonia. The glucose consumption rate is the driving force for setting the perfusion rate. At the end of the run, you can sample the cells.
"Are the Fibra-Cel™ disks (used in the immobilized cell Spinner Basket and CelliGen Plus® bioreactor) medical-grade certified?"
Yes, they are. FibraCel is a USP Class VI material.
"Which anti-foams are recommended for use in fermentation?"
Our in-house microbiologists report success with the following, though we make no commercial endorsement of these products. For Pichia pastoris, Breox FMT 30 from International Specialty Chemicals (Southampton, UK, www.inspec.co.uk). For E coli and other microorganisms, A 5551 (antifoam 289), A 5757 Antifoam B Emulsion, and A 6426 (Antifoam 204 by Mazur), available from Sigma (St. Louis, Missouri), www.sigma.sial.com
“How does 316L stainless steel, (used to make NBS vessels), stand up to use with common chemicals?”
316 L stainless steel is extremely corrosion-resistant, and is considered to be the industry standard for manufacture of ASME-coded vessels. However, a variety of bioprocess operating conditions will influence its resistance to chemical solutions, including temperature, chemical concentration, aeration, recirculation, inhibiting or accelerating contaminants, solids in suspension, velocity, frequency of cleaning and equipment design. For further information about the corrosive properties of our specific chemicals, contact us at 800-631-5417 or 732-287-1200, ext. 2214.
"I'm a university professor teaching a class of first and second-year microbiology students. Do you have any materials that would be helpful to my class?"
NBS has written two in a series of white papers titled "Fundamentals of Fermentation: Techniques for Benchtop Fermentation", covering such topics as media formulation, nutrient addition, as well as preparation, autoclaving and clean up procedures. A second paper entitled "Fermentation Basics - E. coli" is also available. Both are down-loadable from our web site. We can also provide product slides and literature by writing to NBS Slide Request at P.O. Box 4005, Edison, NJ 08818-4005.
"Last week we ran out of oxygen in the middle of our run, killing our cells and ruining weeks of preparation. Do you have any suggestions?"
Automated gas-alarm systems are available that may be programmed to alert you up to four days before your gas cylinder runs out. NBS offers one such model, catalog number P0440-0340. For further details on any of our wide range of fermentation accessories, contact your local NBS sales representative, or write us with your request.
"Our lab has a mix of fermentors from several manufacturers. Is there any way to automatically data log and control all the systems using just one software package?"
Without question, it is far simpler to maintain just one control system. An analog-to-digital signal converter is available, making it possible to control NBS fermentors with your existing supervisory hardware and software. The system also works in the reverse, allowing NBS' proprietary AFS-BioCommand Windows-based software to data log and control NBS and non-NBS equipment through your desktop PC.
For answers to other frequently asked questions in fermentation, see Fermentation Basics.
"Which CelliGen Plus bioreactor impeller is best for my application?"
To answer that question, select the cell type and application that best fits your needs from the table below:

Cell Type

For Production of

Impeller

Operating Mode
Suspension MAb from a hybridoma Basket1 Perfusion
Intracellular or membrane-bound protein Marine or Pitched Blade Batch, Fed-batch, Repeated batch
Anchorage-
Dependent		 Secreted recombinant protein Basket1 Perfusion
Cell Lift2 Batch, Repeated batch, Perfusion
lntracellular or membrane-bound protein Cell Lift2 Batch, Repeated batch
Viral vaccine

(with infection of a virus)		 Cell Lift2 Batch, Repeated batch, Perfusion
Basket1 Perfusion
Marine or Pitched Blade2 Batch, Fed-batch, Repeated batch, Perfusion
Suspension
(Insect cells)		 Recombinant protein using the Baculovirus expression system Pitched Blade Batch, Fed-batch, Repeated batch

1. Basket impeller requires use of Fibra Cel disks.
2. Requires use of microcarriers.