Category: Biofuels

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


Biofuels: As Bad As Some Say They Are?

Here in Ann Arbor, there have been plenty of fireworks on this press release “Study: Biofuels increase, rather than decrease, heat-trapping carbon dioxide emissions” about a new paper published by the University of Michigan. After reading this paper, I can understand what the brouhaha is about because there are quite a few other factors, for evaluating carbon emissions from bio-fuels, that were not included in the paper. If I were writing it, I would also have included information about carbon sequestration, for example. Plants take up carbon dioxide and expel oxygen. This respiration is what grows the plant and in point of fact, all the carbon in the plant is sequestered from carbon dioxide. If we look at corn, for example, The ear of corn is about 10% of the total biomass of the corn plant and the kernel is about 25-50% of that ear. The rest of the plant is ground up and plowed back into the ground. The point being is that a small portion of the sequestered carbons dioxide is actually used for fuel production. We can never get 100% conversion back into fuel from biomass so our sequestration of carbons dioxide is always net positive. This is, of course, just one example. There are many other factors that could have been included.

David Slomczynski, Ph.D; Geometrick Enterprises