Inspired by the non-flexibility of microeunicellols A and B , we first proposed a biosynthetic pathway that includes a hypothesized terpene synthase, oxidase(s), and methyltransferase (Supplementary Figure ). Then, we targeted the producing strain and did the genome sequencing and genome mining analysis , focusing on terpene synthases. Regrettably, no evident terpene synthase gene clusters with oxidases were discovered, indicating that the obtained bacterium was not the original producing strain, which was later confirmed by fermentation analysis. However, to the best of our luck, we found a Chinese patent detailing the production of a microeunicellol-like compound by a bacterium named Micromonospora sp. HM134 (Supplementary Figure ). Despite the inaccessibility of this patented strain, we observed that the genome of this strain is publicly available in the NCBI database. We then easily pinpointed the microeunicellol-like gene cluster by searching for gene clusters comprising terpene synthase, oxidases, and methyltransferase (Fig. ). In the light of the linear operon-like gene cluster, we designated genes as MicA-MicF to facilitate subsequent analysis, with MicA being the targeted terpene synthase. To assess the catalytic activity of MicA, the gene encoding MicA was commercially synthesized into the bacterial expression vector, pET28a, utilizing BamH I and Hind III as restricted cut sites while preserving the N-terminal His 6 -tag.