The SELDI ProteinChip technology used in this study is capable of detecting proteins at picomolar to femtomolar levels in small native biological mixtures with little or no preparation. It was found here to identify a number of collagen-binding proteins in crude biosurfactant preparations from four probiotic Lactobacillus
strains. While the p26 collagen-binding protein present in L. fermentum
RC-14 exerts anti-adhesive activity against uropathogenic bacteria (2a
), the roles of the other putative collagen-binding proteins identified in this study have yet to be determined and are the subject of ongoing investigations.
The ability of Lactobacillus
biosurfactants to prevent uropathogens from adhering to surfaces (10
) and subsequently infecting healthy human tissue is believed to account, in part, for the beneficial clinical effects of these probiotics (5
). Based on this notion, the extent of collagen binding activity present in Lactobacillus
-produced biosurfactants was determined by the SELDI-TOF technique. Collagen is a major ECM component of the dermis that facilitates attachment of invading pathogenic bacteria (e.g., S. aureus
). Thus, the ability of lactobacilli to produce collagen-binding proteins could explain one aspect of the organisms' protective ability on surfaces and in the urogenital tract.
The SELDI-TOF ProteinChip array system is an excellent system for screening strains for the presence of collagen-binding proteins and for identifying other factors which may be important in potential clinical application of the bacteria. Here, L. fermentum
RC-14 not only produced more collagen-binding proteins, but it alone produced p26. The fact that L. casei
Shirota, a strain used in the commercial probiotic Yakult, did not produce the p26 protein illustrates that not all probiotic lactobacilli are identical, and without verification of their activity in the human urogenital tract, these organisms should not be universally given to humans to treat or prevent urogenital disease. The differences in the levels of expression of collagen-binding proteins may be of clinical significance for another reason; namely, some may better inhibit pathogenic microorganisms (such as S. aureus
) binding to ECM proteins (2
In conclusion, SELDI ProteinChip arrays provide researchers with a powerful means of quickly characterizing proteins and specific protein-protein interactions. The tremendous versatility of this ProteinChip technology makes it particularly useful for more extensive biochemical and microbiological applications, including the development of specific protein expression databases. For example, one could envision the development of biofilm- or probiotic-specific proteome databases. Taken together, these studies may lead to the discovery of novel, clinically important antimicrobial factors.