[UV-mutagenesis in Bacillus subtilis. IV. Analysis of revertants to methionine prototrophy]

UV light induces in Bacillus subtilis met5 ade6 two classes of revertants to prototrophy to methionine which can be easily distinguished by their phenotype: double (Met+Ade+) and solitary (Met+) revertants. Crosses of revertants with the wild type, carried out in transformational experiments, showed that original (direct) mutation met5 is presented in chromosome of double revertants. Consequently they are extragenic suppressor revertants. In the chromosome of solitary revertants Met+ an extragenic suppressor was not detected; reversions Met+ seem to be of an intragenic nature. It is possible to use reversions to prototrophy to methionine as a model to study UV-mutagenesis in suppressor and non-suppressor genes.