L(+)-lactic acid production by co-fermentation of glucose and xylose with Rhizopus oryzae obtained by low-energy ion beam irradiation.

Low-energy ion beam irradiation (10-200 keV) has been proved to have a wide range of biological effects in recent years. When Rhizopus oryzae PW352 was irradiated with a 15-keV low-energy ion beam an L(+)-lactic acid high-yield mutant, RQ4015, was obtained. When 150 g/l glucose was used as the sole carbon source, L(+)-lactic acid of RQ4015 reached 121 g/l after 36 h shake-flask cultivation.

Mutational spectrum of the lacI gene in Escherichia coli K12 induced by low-energy ion beam.

The mutational spectrum of the genomic lacI gene induced by low-energy nitrogen ion irradiation in wild type Escherichia coli strain W3110 were compared with the spontaneous and the vacuum controls. The mutant frequency of irradiated group was dose-dependent and reached 26.3 x 10(-6) at dose of 31.