Metabolic and process engineering on the edge—Rhamnolipids are a true challenge: A review

Recombinant rhamnolipid production circumvents challenges connected to the usage of pathogenic wild-type producers such as Pseudomonas aeruginosa. In order to construct an efficient recombinant strain, two major elements are needed: an optimized expression cassette for the heterologous genes and a chassis cell, optimized for rhamnolipid production. Methods and approaches for the design of expression cassettes and chassis are presented here. With a performing whole-cell catalyst in hand, efficient rhamnolipid production requires advanced process engineering. Especially with heavily foaming substances as rhamnolipids, much attention has to be turned on fermentation and downstream processing. For foam control different technologies such as mechanical and chemical foam collapsing, foam fractionation, and bubble free aeration are described. The recent approaches summarized here are evidence of a vivid research community investigating the many different facets of recombinant rhamnolipid production using P. putida.