| 摘要 |
PROBLEM TO BE SOLVED: To obtain a newly derived Salmonella bacterium that bears a fundamental DNA sequence, has thymine instead of adenine at a specific site in the sequence, and is useful as a diagnostic system of Salmonella for determining the Salmonella whose strains cannot be determined by this adenine-thymine substitution. SOLUTION: This is a newly derived Salmonella bacterium from elementary Salmonella bearing a fundamental DNA sequence. This derived bacterium has a derived DNA sequence that bears a fundamental sequence including thymine instead of adenine at a specific sito and this adenine-thymine substitution makes it impossible to select the characteristics of conventional Salmonella. The derived bacterium can be returned only by substitution of the thymine with adenine, to the Salmonella bacterium that can be selected by the conventional characteristics. Thus, this derived Salmonella bacterium is returned to the bacterium bearing the fundamental DNA sequence by coming into contact with a mutagenic reagents or a mutation-inducing substances to lose the requirement of histidine whereby the Salmonella strain can be diagnosed. The fundamental DNA sequence is substituted with a base at its specific site to prepare 6 kinds of derivative sequences and the sequence is introduced to Salmonella. |
