Month: November 2016

Fermentation for Everyone

Fermentation – what a broad topic. People think that most fermentation types are different from each other and they really are not. Fermentation is the production of a product in a tank by usually a mono culture (but not always – Belgium ales, kombucha, etc) be it, fungi, bacteria, algae or yeast. Some have unique aspects, like totally anaerobic fermentation, which is really susceptible to oxygen. But, if you know the particulars of the organism, the basic process is not that different.

The big trick, with most fermentation processes are understanding the what the product is and what parameters (micro-organism biochemistry) are needed to produce it. These are considered the parameters of the process. For example, there are many bacterial enzymes, such as alpha-amylase, which are produced by starving the culture for carbon (discussed in papers such as Regulatory factors affecting alpha-amylase production in bacillus licheniformis. ). Knowing the fermentation parameters is important as is what was discussed in 3 previous posts, cleanliness and contamination – B. cereus about contamination – part 1.

An example of dealing with process parameters:  long fermentation times can have issues with contamination.  The longer the process time, the more susceptible the process is. This is where understanding the process and the micro-organism’s characteristics can help define the proper parameters. For example, I performed a 7 day fermentation to produce an enzyme I was interested in studying. The fungus I was studying was grown at a low pH (~pH4.0) to help prevent contamination. Since I understood the growth and  biochemical characteristics of the organism in question, it was easy to determine the best way to alleviate possible contamination and this was by lowering the pH of the initial fermentation broth. This helped to relieve any possible contamination issues. This is just one example of how understanding the parameters can bring you to a successful fermentation.

If you need help with fermentation design, scale-up, or contamination issues, GeoMetrick Enterprises can help.

David Slomczynski, Ph.D; GeoMetrick Enterprises

Calibrations: The More the Merrier?

Actually, more isn’t necessarily better but none is not an option either.

Calibration curves are used to actually determine concentrations of compounds of interest in your samples.This idea being that the lowest and highest unknown concentrations are bracketed by at least 2 standard concentrations from your standard curve. https://terpconnect.umd.edu/~toh/models/CalibrationCurve.html  If a unknown is outside you calibration range, then you need to redo, to bracket that concentration in your curve, as long as the curve is still linear. If the curve cannot be increased, then dilutions are needed to bring the unknown concentration in the calibration range.

One can talk about the time interval between calibrations  (weekly, monthly, etc.). This interval depends on how complex or dirty the samples are. If degradation of the separation is occurring, then a calibration is warranted. EPA test methods, in particular, say what the recommended calibration interval is. Also, if the column is removed for any reason, then a calibration is warranted.

Also, there is the use of duplicate samples, calibration check samples, and spiked samples that can be used during a run. These samples are to access the viability of the calibration curve.  All of these should be used to some extent.

There is quite a bit of information in this post. The point is, one should not ignore these points because they are hard or make analysis more complicated. These should be used to better the analysis.

David Slomczynski, Ph.D; GeoMetrick Enterprises