The selection and characterization of the mutants in bioflocculant bacteria C8 induced by 3 MeV helium ion irradiation

A 3 MeV He2+ beam was used to irradiate C8 (a flocculant-producing bacteria) with a fluence ranging from 1011 to 1013 ions/cm2. The effects on the survival ratio, TTC-dehydrogenase activity, flocculating activity and RAPD analysis are reported. The survival ratio curve caused by irradiation is proved to be “saddle-shaped”. Eleven mutants were obtained, all of which had a significant change in dehydrogenase activity and most showed a positive change in flocculating activity. RAPD measurements were used to analyse the DNA of mutants with a flocculating activity over 80%, which indicated that all their DNA had been changed by irradiation.