[In vitro reaction between methylene blue and the chromosomal DNA of E. coli].

In the present work, the chromosomal DNA isolated from the bacterium E. coli was treated with methylene blue. Formation of a heat-stable complex with methylene blue and E. coli chromosomal DNA, has changed the hyperchromic characteristics of E. coli DNA to some extent. It seemed possible that in vivo binding of the dye with DNA may inhibit the separation of DNA chains thus preventing the DNA replication.