“…Especially for applications in the (microbial) enhanced oil recovery, rhamnolipids were produced in E. coli using the common T7 expression system (Wang et al, 2007;Han et al, 2014;Jafari et al, 2014;Du et al, 2017), while others established a constitutive expression of rhlAB in E. coli (Kryachko et al, 2013). More frequently, P. putida KT2440 wild type or engineered strains were used as heterologous host for rhamnolipid biosynthesis using an inducible tac-promoter or constitutive expressed and partly synthetic promoters (Wittgens et al, 2011(Wittgens et al, , 2017Wittgens, 2013;Behrens et al, 2016;Beuker et al, 2016a,b;Tiso et al, 2016Tiso et al, , 2017Tiso et al, , 2020Anic et al, 2017Anic et al, , 2018Noll et al, 2019; Table 1). Besides well-known short-chain rhamnolipids from P. aeruginosa also the heterologous production of long chain rhamnolipids was established in this organism by expressing rhlAB and rhlC from B. glumae .…”