The transcriptional expression of the sn-glycerol 3-phosphate transport gene, glpT, was studied with a glpT-lac fusion contained on a low-copy-number plasmid pFZY1. The fusion was isolated during a ‘shot gun’ cloning of promoters expressed under anaerobic growth conditions. It was shown that glpT was induced six-fold by anaerobiosis. Furthermore, aerobic expression of glpT was induced by the substrate glycerol 3-phosphate, while the anaerobic expression of glpT was decreased by nitrate, glucose and a fnr mutation. However, nitrate repression on glpT expression was relieved if the upstream region from −290 of the transcription site was removed.