Ileal mucus and epithelial cells were isolated from newborn piglets that had never been fed and 35-day-old unweaned piglets. Both newborn and 35-day-old piglet mucus preparations supported growth of Escherichia coli Bd 1107/75 08, a K88-fimbriated porcine enterotoxigenic strain, equally well (i.e., generation times of 28 min were observed in both cases). Adhesion of E. coli Bd 1107/75 08 to 35-day-old piglet ileal epithelial cells was, at most, 2 times that of the same strain to newborn piglet ileal epithelial cells; however, adhesion of E. coli Bd 1107/75 08 to 35-day-old piglet ileal mucus was 16 times that of the same strain to newborn piglet ileal mucus. The receptor in 35-day-old piglet ileal mucus was K88 specific, since it could be removed by purified K88ab fimbriae. Furthermore, adhesion of E. coli Bd 1107/75 08 to 35-day-old piglet Heal mucus was blocked by PAB10, a K88ab-, K88ac-, K88ad-specific monoclonal antibody. Although E. coli Bd 1107/75 08 traversed both newborn and 35-day-old piglet Heal mucus about equally well in vitro and bound well to underlying ileal epithelial cells after passing through newborn ileal mucus, it did not bind to ileal epithelial cells after passing through 35-day-old piglet ileal mucus. The data are discussed with respect to the role that K88-specific receptors present in newborn and ileal mucus might play in the pathogenesis of porcine enterotoxigenic E. coil strains which bear K88 fimbriae.

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The aim of this study was to characterize the Escherichia coli K88-specific receptors in mucus from the small intestines of 35-day-old piglets with the isogenic strains E. coli K-12(pMKO05) (K88+) and E. coli K-12(pMK002) (K88-). These strains differed only in that the latter one cannot produce intact K88 fimbriae because of a deletion in the gene coding for the major fimbrial subunit. Adhesion was studied by incubating 3H-labeled bacteria with crude mucus, pronase-treated whole mucus, mucus fractionated by gel filtration, delipidated mucus, or extracted lipids immobilized in microtiter wells. In addition, E. coli strains were tested for adhesion to glycolipids extracted from mucus by overlaying glycolipid chromatograms with I251-labeled bacteria. The recently reported finding that K88 fimbriae bind to glycoproteins in mucus from the piglet small intestine was confirmed in two ways. Pronase treatment of immobilized mucus reduced adhesion by 82%, and adhesion to delipidated mucus was 14 times greater for the K88+ than for the K88strain. E. coli K88+ adhered to several of the fractions collected after gel filtration of crude mucus, including the void volume (Mr, >250,000). Receptor activity specific for the K88 fimbriae was demonstrated in the lipids extracted from mucus, as the neutral lipids contained six times as much receptor activity as the acidic lipid fraction. Specificity was confirmed by demonstrating that adhesion to the total lipids could be inhibited by pretreatment of the immobilized lipids with K88 fimbriae. Relative to K-12 (K88-), the K-12 (K88+) bacterial cells bound more avidly to galactosylceramide when the neutral lipids were separated on thin-layer chromatography plates. No adhesion to lipids in the acidic fraction separated on thin-layer plates was detected. Relative to adhesion of K-12 (K88-), adhesion of K-12 (K88+) to commercially available galactosylceramide immobilized in microtiter wells confirmed the results with the thin-layer plates. It can be concluded that 35-day-old piglet mucus contains both protein and glycolipid receptors specific for K88 fimbriae, the latter being galactosylceramide.

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WRANGSTADH, M., CONWAY, P. L., and KJELLEBERG, S. 1989. The role of an extracellular polysaccharide produced by the marine Pseudomonas sp. S9 in cellular detachment during starvation. Can. J. Microbiol. 35: 309-312.An exopolysaccharide polymer is produced by the marine Pseudomonas sp. S9 in response to complete energy and nutrient starvation. The presence of this polysaccharide on the cell surface and its subsequent release have been shown to be associated with both adhesion and detachment of the bacterial cells. Detachment from a hydrophobic surface was correlated to the presence of the exopolysaccharide on detached S9 cells. The exopolysaccharide was detected, using immunofluorescence microscopy, on surface-bound cells after only 15 min of exogenous energy and nutrient deprivation. This technique did not reveal any significant amounts of exopolysaccharide on starving bulk phase cells prior to 3 h of starvation. Cells that detached after 5.5 h of starvation had low cell surface hydrophobicity values and increased amounts of cell-bound exopolysaccharide. In contrast, cells that became detached during the first 5.5 h of starvation showed increasing hydrophobicity values during prolonged bulk phase starvation. WRANGSTADH, M., CONWAY, P. L., et KJELLEBERG, S. 1989. The role of an extracellular polysaccharide produced by the marine Pseudomoms sp. S9 in cellular detachment during starvation. Can. J. Microbiol. 35 : 309-312. Le rcile d'un polysaccharide extracellulaire produit par la bactCrie Pseudomonas sp. S9 a Ct C CtudiC dans des conditions de privation complkte en sources d'tnergie et de nutriments. La presence de ce polysaccharide h la surface des cellules et sa libtration subsCquente se sont avCrCes &tre associCes B la fois ?I I'adhCsion des cellules entre elles et h leur libkration par dktachement. Le dCtachement d'une surface hydrophobe a Ct C corrClC avec la detection d'un exopolysaccharide sur les cellules S9 1ibCrCes. Grdce ?I la microscopie en immuno-fluorescence, cet exopolysaccharide a: Ct C dCcelC h la surface des cellules likes entre elles aprks seulement 15 min de privation en sources dlCnergie et de nutriments. Cette technique n'a cependant rCvC1C la presence de quantitCs significatives de l'exopolysaccharide dans la masse de cellules B 1'Ctat de privation totale qu'aprks 3 h de ce rCgime. Aprks 5,s h, les cellules qui se sont dCtachCes ont present6 des valeurs faibles dlhydrophobicitC des surfaces cellulaires et des quantitCs croissantes d'exopolysaccharide liC 2 la surface des cellules. A l'oppost, les cellules qui se sont dCtachCes au cours des 5,s h de privation ont prCsentC des valeurs d'hydrophobicitC croissantes au cours d'une phase prolong& de privation de la masse cellulaire. [Traduit par la revue] Introduction The significance of polysaccharides produced by marine bacteria for adhesion processes has been a subject of discussion during recent years (e.g., Corpe 1970; Geesey 1982; Sutherland 1980; Platt et al. 1985; Tosteson 1985). Although polymers have been shown to contribute to cell surfa...