Over-oxidation of taxadien-5α-ol was found to be a result of high T5αH expression levels in heterologous systems, which led to the formation of polyfunctionalized byproducts. The study demonstrated that lowering the expression levels of T5αH effectively reduced over-oxidation, allowing for a cleaner biosynthesis of desired products. This insight is crucial for metabolic engineering strategies that aim to improve yields of desired natural products in heterologous hosts.