The reverse frequency of donor and receptor for auxotroph and resistance is less than 10~(-9), protoplast transformation is carried out in SMM containing 30% oolyethene glycol (MW 6000) and 20mg/ml DNA at controtledtime and temperature.

• 转化子有的是原养型,有的在含利福平(10单位/亳升)和链霉素(200单位/亳升)的培养基上能生长,也有的兼而有之。