Ability of the exopolymer excreted by Pseudoalteromonas antarctica NF3, tocoat liposomes and to protect these structures against octyl glucoside

The ability of an exopolymer of glycoproteic character (GP) excreted by a n ew gramnegative specie Pseudoalteromonas antarctica NF3, to coat phosphatid ylcholine (PC) liposomes and to protect these bilayers against the action o f the nonionic surfactant octyl glucoside (OG) has been investigated. TEM m icrographs of freeze-fractured liposome/GP aggregates reveal that the addit ion of GP to liposomes led to the formation of a covering structure (polyme r adsorbed onto the bilayers) that tightly coated PC bilayers. The complete coating was already achieved when the proportion of GP assembled with lipo somes was approximately 10% (wt% vs total PC). Higher GP amounts resulted i n a growth of this coating structure which exhibited at the highest GP prop ortion in the system (31% of assembled GP) a multilayered structure. An inc reasing resistance of PC liposomes to be affected by OG both at sublytic an d lytic levels occurred as the proportion of GP in the system rose; this pr otective effect being more effective when the proportion of assembled GP wa s 10-20% in weight. Thus, although a direct dependence was found between th e growth of the enveloping structure and the resistance of the coated lipos omes to be affected by OG, the best protection occurred when the proportion of assembled GP was about 10 wt%.