NAD-dependent dehydrogenase that has high activity with L-rhamnose and L-lyxose, and shows only low activity with L-mannose. Has no activity with NADP. Catalyzes the first step in an alternative pathway for rhamnose utilization that does not involve phosphorylated intermediates. L-rhamnofuranose + NAD(+) = H(+) + L-rhamnono-1,4-lactone + NADH Optimum pH is 9.5. Up-regulated by growth on rhamnose. Part of gene cluster that contains the genes for this rhamnose catabolic pathway. Belongs to the short-chain dehydrogenases/reductases (SDR) family.