How are scientists transforming our understanding of the microbes used in AD?

Although anaerobic digestion is a well-established technology that’s used a lot at industrial scale, the fundamental nuts and bolts of how it works are still not terribly well understood. As has been mentioned, this is a microbiological process but actually it uses a microbial community rather than individual organisms and we know that there are thousands of different sorts of microbes in an anaerobic digester. The challenge that we’re interested in trying to unravel is, what those individuals do, how we can make them behave slightly differently so that we can get better yields or different outcomes from the process and how reproducible and robust this process is.

If we make a change in one anaerobic digester are the microbes going to behave in a predictable way that means that we can make that same change in a different digester and get the same outcome? So the way that we’re trying to understand that is by using DNA sequencing and this has some challenges all of its own. Because this is a microbial community and there’s a mixture of organisms, when we extract DNA we get the DNA from these thousands of different organisms all at the same time. So, rather than trying to separate them out, we take what’s called a shotgun approach and sequence all the DNA that’s there.

Traditionally DNA sequencing has used a technology that can only sequence very short pieces of DNA, maybe 200 letters at a time, and that causes all sorts of problems when it comes to reassembling the DNA so that we can make sense of it. You can imagine, we basically have the worlds’ most complicated jigsaw puzzle with billions of different pieces that all need to be fitted together, most of which look almost exactly the same as each other. So that’s been a very big problem for this kind of shotgun approach.

Recently, there’s new technologies available that allow you to sequence longer pieces of DNA and so that simplifies the problem because all of a sudden our pieces go from very advanced thousand piece jigsaw puzzles to very big pieces of the jigsaw all at once, more like a kiddie jigsaw so putting the information back together becomes a lot easier.