title: Cell wall modifications during osmotic stress in Lactobacillus casei.
abstract: OBJECTIVE
  To study the modification of the cell wall of Lactobacillus casei ATCC 393 grown in high salt conditions.
  
  
  RESULTS
  Differences in the overall structure of cell wall between growth in high salt (MRS + 1 mol l(-1) NaCl; N condition) and control (MRS; C condition) conditions were determined by transmission electronic microscopy and analytical procedures. Lactobacillus casei cells grown in N condition were significantly larger than cells grown under unstressed C condition. Increased sensitivity to mutanolysin and antibiotics with target in the cell wall was observed in N condition. Purified cell wall also showed the increased sensitivity to lysis by mutanolysin. Analysis of peptidoglycan (PG) from stressed cells showed that modification was at the structural level in accordance with a decreased PG cross-link involving penicillin-binding proteins (PBP). Nine PBP were first described in this species and these proteins were expressed in low percentages or presented a modified pattern of saturation with penicillin G (Pen G) during growth in high salt. Three of the essential PBP were fully saturated in N condition at lower Pen G concentrations than in C condition, suggesting differences in functionality in vivo.
  
  
  CONCLUSIONS
  The results show that growth in high salt modified the structural properties of the cell wall.
  
  
  CONCLUSIONS
  Advances in understanding the adaptation to high osmolarity, in particular those involving sensitivity to lysis of lactic acid bacteria.
authors.affiliation: Departamento de Química Biológica, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina.
authors.forename: M
authors.initials: M
authors.lastname: Piuri
authors.forename: C
authors.initials: C
authors.lastname: Sanchez-Rivas
authors.forename: S M
authors.initials: SM
authors.lastname: Ruzal
mesh_terms: D001431:Bacteriological Techniques; D002473:Cell Wall / Q000737:chemistry / Q000648:ultrastructure*; D004351:Drug Resistance; D004591:Electrophoresis, Polyacrylamide Gel; D006868:Hydrolysis; D007780:Lacticaseibacillus casei / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure*; D008854:Microscopy, Electron; D009995:Osmosis; D046915:Penicillin-Binding Proteins / Q000032:analysis; D010457:Peptidoglycan / Q000032:analysis
chemical_list: D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan