FIG. 4.

Immobilization of SAX-expressing L. lactis cells on a biotinylated alkaline phosphatase (B-AP)-coated polystyrene surface. The frame labeled “negative controls” is representative of all negative controls, including administration of SAX-expressing L. lactis to non-B-AP-coated plates, or B-AP-coated plates which were previously blocked with an excess of soluble SA, and administration of prewashed L. lactis cells expressing the secreted SA to all types of pretreated plates used. The preparations were observed through a Zeiss Microsystems Axiovert 100 confocal laser scanning microscope equipped with a 100× objective.