Utilization of a Wheat Sidestream for 5-Aminovalerate Production in Corynebacterium glutamicum

Abstract

Production of plastics from petroleum-based raw materials extensively contributes to global pollution and CO₂ emissions. Biotechnological production of functionalized monomers can reduce the environmental impact, in particular when using industrial sidestreams as feedstocks. <i>Corynebacterium glutamicum</i>, which is used in the million-ton-scale amino acid production, has been engineered for sustainable production of polyamide monomers. In this study, wheat sidestream concentrate (WSC) from industrial starch production was utilized for production of l-lysine-derived bifunctional monomers using metabolically engineered <i>C. glutamicum</i> strains. Growth of <i>C. glutamicum</i> on WSC was observed and could be improved by hydrolysis of WSC. By heterologous expression of the genes <i>xylA</i> _<i>Xc</i> <i>B</i> _<i>Cg</i> (<i>xylA</i> from <i>Xanthomonas campestris</i>) and <i>araBAD</i> _<i>Ec</i> from <i>E. coli</i>, xylose, and arabinose in WSC hydrolysate (WSCH), in addition to glucose, could be consumed, and production of l-lysine could be increased. WSCH-based production of cadaverine and 5-aminovalerate (5AVA) was enabled. To this end, the lysine decarboxylase gene <i>ldcC</i> _<i>Ec</i> from <i>E. coli</i> was expressed alone or for conversion to 5AVA cascaded either with putrescine transaminase and dehydrogenase genes <i>patDA</i> _<i>Ec</i> from <i>E. coli</i> or with putrescine oxidase gene <i>puo</i> _<i>Rq</i> from <i>Rhodococcus qingshengii</i> and <i>patD</i> _<i>Ec</i> . Deletion of the l-glutamate dehydrogenase-encoding gene <i>gdh</i> reduced formation of l-glutamate as a side product for strains with either of the cascades. Since the former cascade (<i>ldcC</i> _<i>Ec</i> -<i>patDA</i> _<i>Ec</i> ) yields l-glutamate, 5AVA production is coupled to growth by flux enforcement resulting in the highest 5AVA titer obtained with WSCH-based media.