Horizontal scaling makes sense and especially for startups. I remember discussing this approach with investor type people interested in biotech and the response

Horizontal scaling makes sense and especially for startups. I remember discussing this approach with investor type people interested in biotech and the response kept falling back on maximum litres and comparison to existing hugeness of reactors. Which I thought was missing the point entirely! Some bioproducts can be sold for $1 million a gram. It doesn't take a genius to realise that size isn't everything in bioreactors.