microorganisms Article CRISPRi-Library-Guided Target Identification for Engineering Carotenoid Production by Corynebacterium glutamicum Vanessa L. Göttl, Ina Schmitt, Kristina Braun, Petra Peters-Wendisch, Volker F. Wendisch * and Nadja A. Henke Genetics of Prokaryotes, Faculty of Biology & CeBiTec, Bielefeld University, 33615 Bielefeld, Germany;
[email protected] (V.L.G.);
[email protected] (I.S.);
[email protected] (K.B.);
[email protected] (P.P.-W.);
[email protected] (N.A.H.) * Correspondence:
[email protected]; Tel.: +49-521-106-5611 Abstract: Corynebacterium glutamicum is a prominent production host for various value-added com- pounds in white biotechnology. Gene repression by dCas9/clustered regularly interspaced short palindromic repeats (CRISPR) interference (CRISPRi) allows for the identification of target genes for metabolic engineering. In this study, a CRISPRi-based library for the repression of 74 genes of C. glutamicum was constructed. The chosen genes included genes encoding enzymes of glycolysis, the pentose phosphate pathway, and the tricarboxylic acid cycle, regulatory genes, as well as genes of the methylerythritol phosphate and carotenoid biosynthesis pathways. As expected, CRISPRi-mediated repression of the carotenogenesis repressor gene crtR resulted in increased pigmentation and cellular content of the native carotenoid pigment decaprenoxanthin. CRISPRi screening identified 14 genes that affected decaprenoxanthin biosynthesis when repressed. Carotenoid biosynthesis was signifi- Citation: Göttl, V.L.; Schmitt, I.; cantly decreased upon CRISPRi-mediated repression of 11 of these genes, while repression of 3 genes Braun, K.; Peters-Wendisch, P.; was beneficial for decaprenoxanthin production. Largely, but not in all cases, deletion of selected Wendisch, V.F.; Henke, N.A.