The biofilm associated protein (Bap) is recognised as the essential component for biofilm formation in Staphylococcus aureus V329 and other species. Although Bap orthologs are also present in most S. xylosus strains, their contribution to biofilm formation has not yet been determined. In this study, different experimental approaches were used to elucidate the effect of Bap on biofilm formation in S. xylosus and the motif structure of two biofilm-forming S. xylosus strains TMW 2.1023 and TMW 2.1523 was compared to Bap of S. aureus V329. We found that despite an identical structural arrangement into four regions, Bap from S. xylosus differs in key factors to Bap of S. aureus i.e. isoelectric point of aggregation prone Region B, protein homology and type of repeats. Disruption of bap had no effect on aggregation behavior of selected S. xylosus strains and a significant reduction in biofilm was only observed for one strain (TMW 2.1523) under neutral conditions. Further we could not observe any typical characteristics of a S. aureus Bap positive phenotype such as functional impairment by calcium addition and rough colony morphology on CRA. A predominant role of Bap in cell aggregation and biofilm formation as reported for S. aureus V329 was not observed. We therefore suggest that biofilm formation follows different, multifactorial mechanisms, and cannot be referred to as the primary function of Bap in S. xylosus.