This study demonstrates that growth temperature significantly alters the lipopolysaccharide (LPS) structure of Yersinia enterocolitica strain Ye 3827, affecting both bacteriophage sensitivity and antigenicity. Bacteria grown at 25°C produced smooth LPS that efficiently inactivated multiple bacteriophages (I-IX), while bacteria grown at 37°C exhibited a partial smooth-to-rough transition, producing LPS that required over 3000-fold more material to achieve equivalent phage inactivation. Chemical analysis revealed that 37°C-grown cells had substantially reduced levels of the O-specific polysaccharide (6-deoxy-L-altrose) and increased R-core components compared to 25°C-grown cells. The antigenic determinants also differed: antibodies from rabbits immunized with 25°C-grown bacteria primarily recognized the O-polysaccharide portion, while antibodies from 37°C-grown bacteria predominantly recognized the R-core. Isolation of a phage-resistant rough mutant confirmed that bacteriophage receptors are located on the LPS, specifically requiring the O-polysaccharide chain. The authors suggest that acid-labile determinants such as O-acetyl groups may be responsible for the temperature-dependent changes in phage sensitivity, as the O-polysaccharides isolated from both temperatures had similar basic composition.

Key findings

• Growth temperature causes partial smooth-to-rough LPS transition in Y. enterocolitica, with 37°C-grown bacteria producing significantly reduced O-polysaccharide content compared to 25°C-grown bacteria
• LPS from 25°C-grown cells inactivates bacteriophages 3000-fold more efficiently than LPS from 37°C-grown cells, indicating temperature-dependent changes in phage receptor accessibility
• Antigenic determinants are temperature-dependent: 25°C-LPS antigens are O-polysaccharide-based while 37°C-LPS antigens are primarily R-core-based
• Acid-labile substituents such as O-acetyl groups on the O-polysaccharide likely mediate the dramatic differences in bacteriophage sensitivity despite similar overall sugar composition