Novel Screening of Antibiotic-Sensitive Biofilm-Forming Mutants by Utilizing a Product of Serratia marcescens

Abstract

To study the resistance of biofilms to antibiotics, it is necessary to screen for mutant bacteria which are sensitive to antibiotics. To screen a vast number of mutants, we used a red pigment of Serratia marcescens strain 274 as a marker which could be identified by the naked eye. With this method, we selected ampicillin (ABPC)-sensitive biofilm-forming mutants from among S. marcescens transposon5 (Tn5) mutants. Four groups were screened and three were analyzed genetically. The Tn5 inserted gene of two groups was thought to be concerned with the formation of exopolysaccharides. The other group has an insertion of Tn5 into a gene which has high sequence similarity to the gene for ferric enterobactin-binding protein. It, however, was confirmed that all of the screened mutants formed ABPC-sensitive biofilms. Therefore this method was demonstrated to be beneficial for the screening of antibiotic-sensitive biofilm-forming mutants.