| 摘要 |
A method for preventing the expression of undesired gene products, and a process for improving the method of obtaining desired products from the expression of growing cellular microorganisms, both comprising inserting an altered plasmid, are disclosed and claimed. In particular disclosed are: a method for preventing the expression of the autolytic enzyme (the N-acetylmuramoyl-L-alanine amidase) of Streptococcus pneumoniae; a method for introducing the inactivated autolysin gene into any one of the Streptococcus pneumoniae strains with chemically different capsules; and a process for using such nonautolysing pneumococci for the production of capsular polysaccharides uncontaminated by cell wall material and thus representing a safer and less costly antipneumococcal vaccine. |
