BIOTECHNOLOGICALLY RELEVANT ENZYMES AND PROTEINS FudC, a protein primarily responsible for furfural detoxification in Corynebacterium glutamicum Yota Tsuge 1 & Motonori Kudou 1 & Hideo Kawaguchi 2 & Jun Ishii 1 & Tomohisa Hasunuma 1 & Akihiko Kondo 2,3 Received: 14 August 2015 /Revised: 19 October 2015 /Accepted: 20 October 2015 /Published online: 6 November 2015 # Springer-Verlag Berlin Heidelberg 2015 Abstract Lignocellulosic hydrolysates contain compounds that inhibit microbial growth and fermentation, thereby de- creasing the productivity of biofuel and biochemical produc- tion. In particular, the heterocyclic aldehyde furfural is one of the most toxic compounds found in these hydrolysates. We previously demonstrated that Corynebacterium glutamicum converts furfural into the less toxic compounds furfuryl alco- hol and 2-furoic acid. To date, however, the genes involved in these oxidation and reduction reactions have not been identi- fied in the C. glutamicum genome. Here, we show that Cgl0331 (designated FudC) is mainly responsible for the re- duction of furfural into furfuryl alcohol in C. glutamicum. Deletion of the gene encoding FudC markedly diminished the in vivo reduction of furfural to furfuryl alcohol. Purified His-tagged FudC protein from Escherichia coli was also shown to convert furfural into furfuryl alcohol in an in vitro reaction utilizing NADPH, but not NADH, as a cofactor. Kinetic measurements demonstrated that FudC has a high affinity for furfural but has a narrow substrate range for other aldehydes compared to the protein responsible for furfural reduction in E. coli. Keywords Corynebacterium glutamicum . Furfural . Furfuryl alcohol . Alcohol dehydrogenase . NADPH Introduction Furfural (2-furaldehyde) is present at high concentrations in the waste generated during pulp and paper production. Recently, furfural is more focused in the field of microbial production of fuels and chemicals from lignocellulosic bio- mass, which is the most abundant renewable carbon source on earth. Furfural is generated during the dilute acid pretreat- ment of lignocellulosic biomass and inhibits the growth and fermentation of bacteria and yeast (Almeida et al. 2009; Mills et al. 2009). Furfural has been proposed to inhibit microbial growth by damaging DNA and/or inhibiting glycolytic en- zymes (Gorsich et al. 2006; Hadi and Shahabuddin, 1989; Hristozova et al. 2006; Khan et al. 1995). Thus, the identifi- cation or genetic engineering of microbial strains with high tolerance and degradative capacity for furfural is necessary for the efficient microbial production of fuels and chemicals from lignocellulosic hydrolysates. To date, only a few bacterial species have been reported to utilize and degrade furfural as a sole carbon source (Wierckx et al. 2011). Among these predominantly Gram-negative bac- terial species, Cupriavidus basilensis HMF14 was shown to rapidly degrade furfural into 2-oxoglutarate in seven steps catalyzed by enzymes encoded in the hmf operon (Koopman et al. 2010). In contrast, a number of microorganisms are ca- pable of slowly detoxifying furfural to less toxic compounds, such as furfuryl alcohol and 2-furoic acid, even though furfu- ral cannot be utilized as a sole carbon source. For example, Escherichia coli reduces furfural to less toxic furfuryl alcohol using the NADPH-dependent aldehyde reductase YqhD (Miller et al. 2009), whereas in Saccharomyces cerevisiae, * Akihiko Kondo akondo@kobe-u.ac.jp 1 Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan 2 Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyogo 657-8501, Japan 3 Biomass Engineering Program, RIKEN, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan Appl Microbiol Biotechnol (2016) 100:2685–2692 DOI 10.1007/s00253-015-7115-y