In the fermentative production of compounds by using microorganisms, control of the transporter activity responsible for substrate uptake and product efflux, in addition to intracellular metabolic modification, is important from a productivity perspective. However, there has been little progress in analyses of the functions of microbial membrane transporters, and because of the difficulty in finding transporters that transport target compounds, only a few transporters have been put to practical use. Here, we constructed a Corynebacterium glutamicum-derived transporter expression library (CgTP-Express library) with the fusion partner gene mstX and used a peptide-feeding method with the dipeptide L-Ala-L-Ala to search for alanine exporters in the library. Among 39 genes in the library, five candidate alanine exporters (NCgl2533, NCgl2683, NCgl0986, NCgl0453, and NCgl0929) were found; expression of NCgl2533 increased the alanine concentration in cell culture. The CgTP-Express library was thus effective for finding a new transporter candidate.
Keywords: Corynebacterium glutamicum; fermentative production; fusion partner protein; transporter.