The methylotrophic yeast Pichia pastoris is widely used in the manufacture of industrial enzymes and pharmaceuticals. Like most biotechnological production hosts, P. pastoris is heterotrophic and grows on organic feedstocks that have competing uses in the production of food and animal feed. In a step toward more sustainable industrial processes, we describe the conversion of P. pastoris into an autotroph that grows on CO 2 . By addition of eight heterologous genes and deletion of three Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:

BackgroundState-of-the-art strain engineering techniques for the host Pichia pastoris (syn. Komagataella spp.) include overexpression of homologous and heterologous genes, and deletion of host genes. For metabolic and cell engineering purposes the simultaneous overexpression of more than one gene would often be required. Very recently, Golden Gate based libraries were adapted to optimize single expression cassettes for recombinant proteins in P. pastoris. However, an efficient toolbox allowing the overexpression of multiple genes at once was not available for P. pastoris.MethodsWith the GoldenPiCS system, we provide a flexible modular system for advanced strain engineering in P. pastoris based on Golden Gate cloning. For this purpose, we established a wide variety of standardized genetic parts (20 promoters of different strength, 10 transcription terminators, 4 genome integration loci, 4 resistance marker cassettes).ResultsAll genetic parts were characterized based on their expression strength measured by eGFP as reporter in up to four production-relevant conditions. The promoters, which are either constitutive or regulatable, cover a broad range of expression strengths in their active conditions (2–192% of the glyceraldehyde-3-phosphate dehydrogenase promoter P GAP), while all transcription terminators and genome integration loci led to equally high expression strength. These modular genetic parts can be readily combined in versatile order, as exemplified for the simultaneous expression of Cas9 and one or more guide-RNA expression units. Importantly, for constructing multigene constructs (vectors with more than two expression units) it is not only essential to balance the expression of the individual genes, but also to avoid repetitive homologous sequences which were otherwise shown to trigger “loop-out” of vector DNA from the P. pastoris genome.ConclusionsGoldenPiCS, a modular Golden Gate-derived P. pastoris cloning system, is very flexible and efficient and can be used for strain engineering of P. pastoris to accomplish pathway expression, protein production or other applications where the integration of various DNA products is required. It allows for the assembly of up to eight expression units on one plasmid with the ability to use different characterized promoters and terminators for each expression unit. GoldenPiCS vectors are available at Addgene.Electronic supplementary materialThe online version of this article (10.1186/s12918-017-0492-3) contains supplementary material, which is available to authorized users.

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Methanol is a liquid with high energy storage capacity that holds promise as an alternative substrate to replace sugars in the biotechnology industry. It can be produced from CO2 or methane and its use does not compete with food and animal feed production. However, there are currently only limited biotechnological options for the valorization of methanol, which hinders its widespread adoption. Here, we report the conversion of the industrial platform organism Escherichia coli into a synthetic methylotroph that assimilates methanol via the energy efficient ribulose monophosphate cycle. Methylotrophy is achieved after evolution of a methanol-dependent E. coli strain over 250 generations in continuous chemostat culture. We demonstrate growth on methanol and biomass formation exclusively from the one-carbon source by 13C isotopic tracer analysis. In line with computational modeling, the methylotrophic E. coli strain optimizes methanol oxidation by upregulation of an improved methanol dehydrogenase, increasing ribulose monophosphate cycle activity, channeling carbon flux through the Entner-Doudoroff pathway and downregulating tricarboxylic acid cycle enzymes. En route towards sustainable bioproduction processes, our work lays the foundation for the efficient utilization of methanol as the dominant carbon and energy resource.