Population dynamics and antagonistic potential of enterococci colonizing the phyllosphere of grasses

Aims: To investigate the spatial and temporal dynamics of enterococci colon izing forage grass and their ability to produce bacteriocins. Methods and Results: Enterococci could be detected on above-ground plant pa rts throughout the growing season, with high continuity but low cell number s (2.60 x 10(1)-6.16 x 10(4) cfu g(-1) fresh matter). A total of 750 strain s were isolated and identified by their whole-cell protein patterns as Ente rococcus faecalis (7.9%), Ent. mundtii (7.9%), Ent. casseliflavus (5.5%), E nt. faecium (5.2%) and Ent. sulfureus (0.1%). The vast majority of the stra ins (69.7%) formed a homogeneous 16S rDNA genotype that differed from those of known enterococci. A screening for antagonistic activity using an agar spot test revealed that 18.4% of all isolates were potential antagonists. P artially-purified proteins extracted from cell-free culture supernatant flu ids of various species were characterized as pH- and heat-stable bacterioci ns active against a wide range of lactic acid bacteria, clostridia and List er ia. The producing strains were antagonistically active even on 'phyllopl ane agar' at temperatures between 4 and 37 degreesC. Conclusions: Enterococci are a common part of the epiphytic microflora of g rasses, displaying probably some antagonistic activity. Significance and Impact of the Study: The results provide new information o n the distribution, species diversity and antagonistic potential of enteroc occi in the phyllosphere.