Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.During aerobic growth, Rhizopus oryzae produces L-lactic acid from lactate dehydrogenase mediated reduction of pyruvate, while O-2 limiting conditions yield primarily ethanol. A mutant was isolated that expressed only 5% of the wild type alcohol dehydrogenase activity under O-2 limiting conditions and produced nearly 40 g lactic acid/l in 70 h. This is almost a ten-fold increase in lactic acid production when compared to the parent strain.