LC-UV/RI-MS2as the analytical platform for bioconversion of sustainable carbon sources: a showcase of 1,4-butanediol plastic monomer degradation usingUstilago trichophora

Abstract

ABSTRACTPlastic usage by microbes as a carbon source is a promising strategy to increase the recycling quota. 1,4-butanediol (BDO) is a common monomer derived from polyesters and polyurethanes. It presents in the complex mixture from the plastic degradation process. In this study,Ustilago trichophorawas found to be an efficient cell-factory to valorize BDO. To investigate product formation byU. trichophora, we refined the traditional ion exclusion liquid chromatography method by examining eluent, eluent concentrations, oven temperatures, and organic modifiers to make the chromatography compatible with mass spectrometry. An LC-UV/RI-MS2method is presented here to identify and quantify extracellular metabolites in the cell cultures. With this method, we successfully identified thatU. trichophorasecreted malic acid, succinic acid, erythritol, and mannitol into the culture medium. Adaptive laboratory evolution followed by medium optimization significantly improvedU. trichophoragrowth on BDO and especially malic acid production. Overall, the carbon yield on the BDO substrate was approximately 33% malic acid. This is the first report on a Ustilaginaceae fungus that was able to convert BDO into versatile chemical building blocks. SinceU. trichophorais not genetically engineered, it is a promising microbial host to produce malic acid from BDO, thereby contributing to the development of the envisaged sustainable bioeconomy.