MODIFICATIONS OF THE S-LAYER OF BACILLUS SPHAERICUS DUE TO AN OSMOTIC STRESS

MARIANA CLAUDIA ALLIEVI; MARIANO PRADO ACOSTA; MARÍA MERCEDES PALOMINO; SANDRA M RUZAL; CARMEN SÁNCHEZ RIVAS

San Miguel de Tucumán Argentina

Congreso; XLV SAIB. 2009; 2009

SAIB

Crystalline surface layers proteins (S-layers) are present in Archeae and Bacteria,have the ability to assemble into crystalline arrays wrapping the cells. S-layers would modify in order to allow a better adaptation to environmental stresses, glycosylation being the most frequent postranslational modification.B sphaericus 2362 possess an S-layer and when expose to high NaCl the cell envelope were thinner and less diffuse than those of control condition. We suspected the S-layer was modified. In order to check if this S-layer plays a role in the osmoadaptation, the growth of cells depleted or not of the S-layer in media containing or not a high salt concentration was compared. Mild treatment with LiCl depletes the S-layer without affecting cell viability. However, these cells showed slower growth rates than cells with intact S-layer in all conditions tested, but particularly in high salt medium. Western blot analysis showed that the synthesis of the S-layer of treated cells, started very early during growth resume. Moreover, the S-layers from cells grown in hypersaline medium presented different mobility and glycosylation patterns compared to those from control medium. Since we have previously observed a pathogenic activity against mosquito larvae with an S-layer from B sphaericus, we are investigating the role of these modifications in such process.