Pathway optimization and membrane engineering for highly efficient production of indigoidine in engineered Escherichia coli

Abstract

Recently, indigoidine has garnered increasing attention and demonstrates significant commercial potential, particularly within the textile industry. As a diphenyl quinone compound, indigoidine shows promise as an alternative colorant due to its superior chemical functionality and stability. Consequently, we engineered Escherichia coli BL21(DE3) containing plasmids to efficiently produce indigoidine using glycerol as the sole carbon source. Initially, eighteen combinations of indigoidine synthases and 4′-phosphopantetheinyl transferases (PPTases) were constructed to identify the most effective enzyme combination for indigoidine production. Subsequently, the rate-limiting steps were identified through the supplementation of various precursors. The titer of indigoidine was significantly enhanced through the optimization of its biosynthetic pathway and membrane engineering. Ultimately, a systematic optimization of the fermentation parameters for the engineered BIG33 strain was conducted in shake-flask experiments. As a result, the maximal indigoidine titer reached 4.95 and 26.71 g/L by shake-flask cultivation and fed-batch fermentation, respectively.