Changes in these characteristics can occur through mutations, which are permanent genetic changes. Serratia marcescens produces prodigiosin, a red pigment. Production of this pigment is dependent upon a number of genes that code for enzymes involved in the production of intermediates in the prodigiosin pathway. By isolating and analyzing mutants in biochemical pathways for amino acid and vitamin synthesis they determined that mutations in a gene could result in a change in the function of the corresponding protein product. Mutations in genes coding for enzymes in the prodigiosin pathway of S. marcescens result in colonies that are pink, tan, white and orange.
Mutations can be spontanous or induced.
Induced mutagenesis occurs via several mechanisms, including radiation, chemicals, viruses and transposable elements. These cross-linked thymines can not be correctly read by DNA Polymerase during replication and the result is an incorrect insertion of nucleotides in the newly replicated DNA strand. We will attempt to identify mutations in the genes of the prodigiosin pathway by isolating mutants that show altered pigmentation. UV induced mutagenesis is inhibited by organic compounds found in the media. To overcome this inhibition, replace the media with sterile saline.