Optimization of L-lactic acid production of rhizopus oryzae mutant RLC41-6 by ion beam implantation at low-energy

In order to obtain an industrial strain with a higher L(+)-lactic acid yield, the strain Rhizopus oryzae RF3608 was mutated by means of nitrogen ion beam implantation and the mutant strain RLC41-6 was isolated. Under optimal conditions the yield of L(+)-lactic acid produced in a shake-flask reached 133 g/L similar to 137 g/L after 36 h cultivation, indicating that the conversion rate based on glucose was as high as 88% similar to 91% and the productivity was 3.75 g/L center dot h. It was almost a 115% increase in lactic acid production compared with the original strain RF3608.