Mutation of a lipopolysaccharide synthesis gene results in increased biofilm of Stenotrophomonas maltophilia on plastic and glass surfaces

Abstract

Stenotrophomonas maltophilia is a biofilm-forming opportunistic pathogen that is emerging worldwide and demonstrates increasing rates of antibiotic resistance and significant case fatality/ratios in immunocompromised or debilitated patients. This study tested the hypothesis that mutation of a lipopolysaccharide synthesis gene results in increased biofilm of S. maltophilia. Transposon mutagenesis was used to disrupt genes of S. maltophilia clinical isolate X26332 and generated the JB12-23 mutant that produced increased biofilm in comparison to the isogenic parental isolate. Southern hybridisation revealed a single transposon insertion in the JB12-23 mutant. Rescue-cloning and DNA sequencing revealed that the transposon had inserted into the spgM gene of S. maltophilia mutant JB12-23. Biofilm assays revealed that the JB12-23 mutant produced more biofilm on polyvinyl chloride, polystyrene surfaces, and on borosilicate glass in comparison to the parental isolate. Lipopolysaccharide SDS-PAGE showed that the JB12-23 mutant lacked high molecular weight LPS in comparison to the parental isolate.