Arginine impacts aggregation, biofilm formation, and antibiotic susceptibility inEnterococcus faecalis

Abstract

AbstractEnterococcus faecalisis a commensal bacterium in the gastrointestinal tract (GIT) of humans and other organisms.E. faecalisalso causes infections in root canals, wounds, the urinary tract, and on heart valves.E. faecalismetabolizes arginine through the arginine deiminase (ADI) pathway, which converts arginine to ornithine and releases ATP, ammonia, and CO2.E. faecalisarginine metabolism also affects virulence of other pathogens during co-culture.E. faecalismay encounter elevated levels of arginine in the GIT or the oral cavity, where arginine is used as a dental therapeutic. Little is known about howE. faecalisresponds to growth in arginine in the absence of other bacteria. To address this, we used RNAseq and additional assays to measure growth, gene expression, and biofilm formation inE. faecalisOG1RF grown in arginine. We demonstrate that arginine decreasesE. faecalisbiofilm production and causes widespread differential expression of genes related to metabolism, quorum sensing, and polysaccharide synthesis. Growth in arginine also increases aggregation ofE. faecalisand promotes decreased susceptibility to the antibiotics ampicillin and ceftriaxone. This work provides a platform for understanding of how the presence of arginine in biological niches affectsE. faecalisphysiology and virulence of surrounding microbes.