The Type b Capsulation Locus of Haemophilus influenzae: Map Location and Size

Abstract

SUMMARY: Capsulation of Haemophilus influenzae was investigated by genetic transformation with high-molecular-weight deoxyribonucleic acid. The DNA was extracted from a capsulated antibiotic-resistant strain of H. influenzae rd which had received the type b capsulation locus {cap b) by transformation. A non-capsulated polyauxotrophic derivative of strain rdwas used as recipient under conditions which permitted the Cap b transformants (assayed as iridescent colonies) to initiate multiplication promptly. The position of cap b on the H. influenzae chromosome map was established by use of chemically defined agar media selective for transformants which had received pairs of linked markers. The cap b locus lies between leucine and biotin loci, and shows about 80 % linkage to the bio-150 marker. The size of the DNA segment required for Cap b transformation was found by physical methods to be about 33 million daltons.