Doing due diligence and doing due diligence well are separate things. I have seen so many fictional or peri-impossible (impossible or "extremely implausible at current tech levels") tech get venture in silicon valley.

For example, there was a company called blue turtle that claimed to want to build a bacterium that provided gaucher's disease enzyme as a probiotic supplement. I mean technically speaking it's not impossible, but there are so many things that 'dont exist yet and would need to be engineered' that I couldn't see it making it as a company.

Oh, absolutely. A lot of VC firms are quite bad at due diligence. However, if you believe John Carreyrou, the big investors mostly weren't thinking along those lines, and some attempts to get investment from real VCs were stymied by the most basic due diligence (one pulled out when Theranos was unable to produce audited accounts, for instance).

Notably, one early investor said, in interviews, that he was comfortable investing because Holmes' grandfather was a businessman, and another relative was a famous doctor (presumably the theory was that she was thus _genetically_ good at medical tech businesses?!). These were, by and large, very much the opposite of sophisticated investors.

To be fair, engineering bacteria to produce a single enzyme as an MVP is an afternoon activity for a single person. You can watch it done on youtube. (you do have to wait some weeks to get your gene sequences or plasmids or whatever manufactured then you have to culture etc. and it doesn’t always work…) But in general it’s not out of the ordinary to think you could do the engineering part in a day.

Even a trivial due dill on cerezyme which is the gaucher's disease enzyme that blue turtle was proposing would have revealed that approved formulation is encapsulated in a membrane, has a membrane anchor (which bacteria cannot natively produce), has glycosylated protein (which bacteria cannot natively produce), not to mention "how the hell do you deliver a protein through the intestinal barrier" and "how do you target probiotic to the intestine", "how do you keep intestinal probiotics there", "what is the plan to measure uptake variations in the population" etc. etc.

Like seriously, i was able to look this up on wikipedia in the timespan of their demo pitch.