A recent edition of “Chemical Engineering Progress” (a magazine from the American Institute for Chemical Engineers), has an interesting section on “Microbiome Engineering”, as illustrated on the cover. This subject nicely illustrates the diversity of directions that chemical engineers might find in a career path.

A microbiome is essentially a community of various types of microbes that live in an environment. Most of this section discusses the human gut microbiome, those trillions of bacteria that live in our bodies in the digestive tract. Apparently, of all the cells in a human body, about 57% of them are microbial (i.e. bacteria, yeast, etc.), and the rest are human cells.

The microbiome in the gut contains about 3,000 different microbial species. In recent years evidence has been mounting that these microbes play key roles in human nutrition, metabolic diseases (like diabetes), mood disorders, and immune system regulation and disorders. Recent information suggests that people with a poor gut microbiome may be more susceptible to COVID-19 infection and severe complications, for example. There is a lot still to be learned about what constitutes a “good” gut microbiome, and how to manipulate it to improve health.

Of particular interest to chemical engineers is the question of how to manufacture so-called “living biotherapeutic products” (LBPs) that could be implanted or swallowed to modify the gut microbiome and cure diseases. Most pharmaceuticals are either chemicals (single or mixtures) or inactivated (dead) parts of microbes or viruses (as used in vaccines). Producing a living product that can grow and thrive in the gut is a somewhat new challenge, especially if it needs to be a complex mixture of microbes.

Some of these engineering/manufacturing challenges would include issues like:

• How to shield the manufacturing process and product from oxygen, since many of these gut microbes may be negatively affected by exposure to oxygen (so-called obligate anaerobes).
• How to get the multiple species of microbes assembled into the LBP. Grow them all separately then mix? Some may grow better in the presence of other species, due to their complex nutritional requirements and symbiotic effects. Growing mixtures of microbes is much more difficult to control if they grow at different rates.
• How to ensure the final LBP product is consistently the same every time it’s produced. The growth history of microbes can affect their final performance and capabilities, even if they are genetically the same. What we call “process control” in chemical engineering will be crucial to consistency of products.

This area of Living Biotherapeutic Products of quite a new one, although it has certain similarities to existing industrial processes like the production of baker’s yeast or Bifidobacteria for dairy starter cultures. As the medical science evolves and promising new therapeutics are identified, chemical engineers will definitely be involved in translating these developments into manufacturing processes that meet future needs.