Abstract
Bacillus subtilis (natto) MAFF 118147 produced a defective bacteriophage, different in DNA size from PBND8, a previously reported defective phage of B. subtilis (natto) IAM 1207. The phage, named DF118147, had a small head (diameter 40 nm) and contractile tail (17 × 264 nm). Its DNA was 13.5 kb in size and yielded a smear pattern in gel electrophoresis after digestion with Hin dIII. Following acridine orange treatment, a mutant of B. subtilis (natto) MAFF 118147, in whose culture the 13.5-kb DNA fragment was not detected, was obtained. Electron microscopy observation showed that the head and tail of the defective phage produced by the mutant were not joined. A mutant yielding no normal defective phage particles is useful as a host in which other types of bacteriophage are amplified, especially for isolating their DNA.
