A new test system for screening macromolecular antitumor antibiotics and its application to culture fluids of actinomycetes.

In searching for macromolecular antitumor antibiotics, a new screening method was developed that consisted of 1) a macromolecular antibiotic detecting system employing macro-molecule permeable mutants of Escherichia coli, 2) a system to detect DNA-affecting antibiotics using DNA repair mutants, and 3) a mutagenicity detecting system, employing a valine resistance test. This new test system was applied to about 2,900 kinds of culture fluids of Actinomycetes and consequently 15 samples were found which contained macromolecular antibiotics with DNA affecting properties.