Distribution of endo-beta-N-acetylglucosaminidase amongst enterococci

Enterococci are becoming increasingly important nosocomial pathogens, a fac t mainly attributed to their antimicrobial resistance profiles. However, th e enzymic activities required for these organisms to proliferate in vivo ha ve received little attention. Enterococcus faecalis has been shown previous ly to produce an endo-beta -N-acetylglucosaminidase activity which cleaves high mannose-type glycans in glycoproteins between the N-acetylglucosamine residues of the pentasaccharide core. This study investigated the distribut ion of this endoglycosidase activity amongst the other enterococcal species . Ribonuclease B, a high mannose-type glycoprotein, was used as a substrate and endoglycosidase activity was demonstrated by a combination of matrix-a ssisted laser desorption ionisation time-of-flight mass spectrometry and hi gh pH anion-exchange chromatography. Endo-beta -N-acetylglucosaminidase act ivity was present in 10 of the 18 enterococcal species isolated from both h uman and animal sources, including all E. faecalis strains. The most notabl e exception was the lack of this activity in all E. faecium isolates tested . All enterococcal species possessing endoglycosidase activity utilised the liberated glycans to support bacterial growth.