GENETICAL STUDIES OF NONCONJUGATIVE SULFANIAMIDE RESISTANCEPLASMID IN GRAM - NEGATIVE BACTERIA

Abstract

We performed the genetic analysis of non-conjugative single sulfanilamide (Su) -resistant gene (s) on gram-nagative bacteria. Almost all of the strains with non-conjugative Su restance carried nonconjugative Su plasmid, pSu. The molecular weight of most non-conjugative pSu plasmids ranged from 3.7 to 3.8 Md. pSu, except one, is mostly due to the formation of Su-resistant dihydropteroate synthetase (DHPS). From the transformation analysis, pSu plasmids were not restricted by Echerichia coli K12 restriction endonuclease system. Also DNA replication of the pSu plasmids required DNA polymerase 1. In addition, the pSu plasmid can be amplified in the presence of chloramphenicol. However, pSu plasmids are compatible with another multiple plasmids.