Abstract:Type I polyketide synthases (PKS) play an important role in catalyzing the biosynthesis of polyketides, which is widely used in medicine and other fields. According to different acyltransferase (AT) domains, type I PKS can be divided into cis-Acyltransferase (cis-AT) PKS and trans-Acyltransferase (trans-AT) PKS, the former has been studied more thoroughly at present, and the related research of the latter has become a hot spot. In this paper, the connections and differences between cis-AT PKS and trans-AT PKS, as well as engineering progresses, related applications and currently existing problems are reviewed, to provide a reference for understanding the role of cis-AT PKS and trans-AT PKS in the biosynthesis of polyketides.